https://wiki.hydrogenaud.io/api.php?action=feedcontributions&user=Kl33per&feedformat=atomHydrogenaudio Knowledgebase - User contributions [en]2024-03-28T12:38:42ZUser contributionsMediaWiki 1.22.7https://wiki.hydrogenaud.io/index.php?title=Nero_AACNero AAC2006-07-06T12:30:12Z<p>Kl33per: Major update due to release of cmd line encoder, more work needed</p>
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<div>A commercial implementation of both LC AAC and HE AAC, Nero AAC is produced by Nero AG as part of their Nero Digital line of products. It is generally precieved to have the highest quality [[VBR]] LC AAC implementation (although QuickTime bests it in [[CBR]] mode at 128kbps). The codec can also create HEv1/v2 AAC streams for extremely low bitrates and supports multi-channel surround sound encoding. As of May 2006, Nero AAC is availble for free as a commandline tool called "Nero Digital Audio".<br />
<br />
==Command Line Options==<br />
<br />
===Usage===<br />
neroAacEnc.exe [options] -if <input-file> -of <output-file><br />
<br />
<input-file>: Path to source file to encode. The file must be in Microsoft WAV format and contain PCM data. Specify - to encode from stdin.<br />
<br />
<output-file>: Path to output file to encode to, in MP4 format.<br />
<br />
===Quality/Bitrate Control===<br />
<br />
'''-q <number>''':<br />
Enables "target quality" mode. <number> is floating-point number between 1 and 10.<br />
<br />
'''-br <number>''':<br />
Specifies "target bitrate" mode. <number> is target bitrate in bits per second.<br />
<br />
'''-cbr <number>''':<br />
Specifies "target bitrate (streaming)" mode. <number> is target bitrate in bits per second.<br />
<br />
When none of above quality/bitrate options is used, the encoder defaults to equivalent of -q 0.5<br />
<br />
===Multipass Encoding===<br />
'''-2pass''':<br />
Enables two-pass encoding mode. Note that two-pass more requires a physical file as input, rather than stdin.<br />
<br />
'''-2passperiod <number>''': Overrides two-pass encoding bitrate averaging period, in milliseconds. Specify zero to use least restrictive value possible (default).<br />
<br />
===Advanced Features / Troubleshooting===<br />
'''-lc''': Forces use of LC AAC profile (HE features disabled)<br />
<br />
'''-he''': Forces use of HE AAC profile (HEv2 features disabled)<br />
<br />
'''-hev2''': Forces use of HEv2 AAC profile<br />
<br />
Note that the above switches (-lc, -he, -hev2) should not be used; optimal AAC profile is automatically determined from quality/bitrate settings when no override is specified.<br />
<br />
'''-hinttrack''': Generates an RTP hint track in output MP4 file.<br />
<br />
'''-ignorelength''': Ignores length signaled by WAV headers of input file. Useful for certain frontends using stdin.<br />
<br />
== External References ==<br />
<br />
[ftp://ftp6.nero.com/infosheets/Nero_Digital/db_nerodigital5.pdf Nero Digital PDF]<br />
<br />
[http://www.nerodigital.com/ Nero Digital Website].</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=LosslessLossless2006-02-19T15:23:29Z<p>Kl33per: Fixed broken link</p>
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<div>'''Lossless compression''' is a compression methodology in which the result of the compression can be restored faithfully, i.e. bit-by-bit identical with the uncompressed data.<br />
<br />
In a nutshell, it is somewhat like compressing a Waveform file with ZIP or RAR.<br />
<br />
The difference between 'mere' ZIP/RAR is that lossless compression algorithms are especially tuned and designed for the characteristics of Waveform data, thus achieving compression far greater than can be achieved by generic compression utilities.<br />
<br />
As lossless compression preserves all information of the original Waveform file, audio compressed with lossless compression will unavoidably be larger than audio compressed with [[lossy]] compression. However, this disadvantage is more than offset by lossless' ability to be [[transcoding|transcoded]] to other lossless format <u>without</u> any quality degradation.<br />
<br />
<br />
=Popular lossless formats=<br />
* [[Apple Lossless]] ([[ALAC]])<br />
<br />
* [[FLAC]]<br />
<br />
* [[Lossless Audio]] ([[LA]])<br />
<br />
* [[LPAC]]<br />
<br />
* [[MLP]]<br />
<br />
* [[Monkey's Audio]] ([[APE]])<br />
<br />
* [[OptimFROG]]<br />
<br />
* [[RKAU]]<br />
<br />
* [[Shorten]] ([[SHN]])<br />
<br />
* [[TTA]]<br />
<br />
* [[WavPack]]<br />
<br />
* [[WMA | WMA lossless]]<br />
<br />
<br />
=Oddball Formats=<br />
There are several old lossless formats that aren't really deserving of having an article all for themselves. Reasons are: lack of widespread support, lack of features, bad efficiency and, most importantly, it seems noone is really interested in them.<br />
<br />
Most of those would have disappeared by now, but they are being preserved for posterity at [[User:Rjamorim|rjamorim]]'s [http://www.rjamorim.com/rrw/ ReallyRareWares]<br />
<br />
; Advanced Digital Audio (ADA)<br />
<br />
* http://www.rjamorim.com/rrw/ada.html<br />
<br />
; Marian's a-Pac<br />
<br />
* http://www.marian.de/en/downloads#APAC<br />
* http://www.rjamorim.com/rrw/apac.html<br />
<br />
; AudioZip<br />
<br />
* http://www.rjamorim.com/rrw/audiozip.html<br />
<br />
; Dakx WAV<br />
<br />
* http://www.dakx.com/<br />
* http://www.rjamorim.com/rrw/daxwav.html<br />
<br />
; Entis Lab MIO<br />
<br />
* http://www.entis.gr.jp/eri/frame.html<br />
* http://www.rjamorim.com/rrw/mio.html<br />
<br />
; LiteWave<br />
<br />
* http://www.clearjump.com/products/LiteWave.html<br />
* http://www.rjamorim.com/rrw/litewave.html<br />
<br />
; Pegasus SPS<br />
<br />
* http://www.krishnasoft.com/sps.htm<br />
* http://www.rjamorim.com/rrw/pegasussps.html<br />
<br />
; RKaudio<br />
<br />
* http://www.msoftware.co.nz/downloads_page.php<br />
* http://rksoft.virtualave.net/rkau.html<br />
<br />
; Split2000<br />
<br />
* http://www.rjamorim.com/rrw/split2000.html<br />
<br />
; Sonarc<br />
<br />
* http://www.rjamorim.com/rrw/sonarc.html<br />
<br />
; VocPack<br />
<br />
* http://www.rjamorim.com/rrw/vocpack.html<br />
<br />
; WavArc<br />
<br />
* http://www.rjamorim.com/rrw/wavarc.html<br />
<br />
; WaveZip/MUSICompress<br />
<br />
* http://members.aol.com/_ht_a/sndspace/<br />
* http://www.rjamorim.com/rrw/wavezip.html<br />
<br />
<br />
Note that currently '''no single format can be considered best for all applications'''. Rather, the best format depends on the ''intended use'', as well as a number of other factors (such as licensing and file structure). For example, Shorten and FLAC are widely used for sharing live music because of their cross-platform support and speed. Monkey's Audio is popular among Windows users for its superior compression ratio.<br />
<br />
=Comparisons=<br />
''Note the specific assumptions and limitations of each comparison; in particular, results are sensitive to the music selected'''<br />
<br />
; http://web.inter.nl.net/users/hvdh/lossless/lossless.htm : Includes an interesting graph of encode/decode speeds vs. file size on the All Albums page<br />
<br />
; [[Lossless comparison]] : A comparision focusing more on codec features and less on absolute encoding efficiency. Also features a table comparing most popular codecs based on their features.<br />
<br />
; http://members.home.nl/w.speek/comparison.htm : Performance Comparison of Lossless Audio Compressors - Compares file size, encode speed, decode speed for [[APE]], [[FLAC]], [[LPAC]], [[WavPack]], Shorten ([[SHN]]), [[RKAU]], [[OptimFROG]], [[LA]], [[WMA | WMA Lossless]]. Updated 5-2003</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=User:Kl33perUser:Kl33per2005-10-03T15:11:42Z<p>Kl33per: Added a bunch of stuff about my guitar rig and my computer</p>
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<div>I'm a student at the Queensland University of Technology Gardens Point Campus, in Brisbane, Australia. I'm studying a Bachelor of Information Technology.<br />
<br />
My main hobby is music. My primary instrument is the guitar, and I specialise in jazz. Obviously music is fairly important in my life. Combine that with my interest in computers, and it's fairly obvious why I'm part of the HA.org community. For the record, I currently compress my music with Monkey's Audio on Extra High and Nero AAC on Streaming and Fast mode.<br />
<br />
<br />
== My Guitar Rig ==<br />
{|<br />
|http://users.tpg.com.au/~adsll926/guitar/fullguitar.jpg<br />
|I'm currently playing a custom Strat. The guitar was built by John Youngberg of Brisbane, Queensland. It's a very strange strat I'll give you that, but that's the way I wanted it. It's a maple neck with a rosewood figureboard. The neck is bolted onto the body with four bolts. The neck pickup is a [http://www.dimarzio.com/ Dimarzio] Air Classic (Neck Model). I cannot remember what the center pickup is. I know it's built by an American company and it sounds much like a standard Fender strat pickup. The bridge pickup is a PAF. The tuning heads are locking sperzel's. The bridge is the same one used on the Fender Jazzmaster. It's similar to a Floyd-Rose in that you can get large bends, but doesn't suffer the associated tuning issues.<br />
|}<br />
{|<br />
|http://users.tpg.com.au/~adsll926/guitar/guitarbody.jpg<br />
|Yep, those controls look a little funky, so let me explain. First there's the mysterious pickup behind the bridge pickup. This is a [http://www.rolandus.com/products/details.asp?catid=6&subcatid=0&prodid=GK%2DKIT%2DGT Roland GK-2A Internal Kit Pickup]. It allows the guitar to connected to Roland's line of synth products, as well as other compatible GK devices. Both Roland and BOSS currently make a series of GK products. I currently own two of these the [http://www.rolandus.com/products/details.asp?catid=6&subcatid=0&prodid=GR%2D33 GR-33], a guitar synthesizer using MIDI, and the [http://www.rolandus.com/products/details.asp?catid=6&subcatid=0&prodid=VG%2D88+v%2E2 VG-88], arguably the world's greatest, and most versatile guitar effects unit. I'll get to it's capabilities in a moment.<br />
<br />
The five switches in a row (on the right) control pickup selection. They are push/push style buttons. The first three buttons turn pickup's one, two, and three on/off, while the last two split the neck/bridge pickup's for single coil tones. The two switches above the pots are for the Roland GK-2A unit, as is the three way switch. The first pot is volume, the second synth volume, and the third tone for all pickups.<br />
|}<br />
{|<br />
|http://users.tpg.com.au/~adsll926/guitar/vg-88.jpg<br />
|My usual setup is as follows. The guitar is plugged directly into my VG-88. None of the guitar sounds I use on stage are real, they are all generated by the VG-88. It does not use MIDI or any usual synth technology. The notes I play are not converted to pitches. It works by taking the waveform from what I play, and restrucuring it using sophisticated DSP units. The VG-88 is able to simulate a variety of guitar pickups (strat's, tele's, lp's, PAF, and a number of others), bodies (flat, round, metal, f-hole, solid), amps (JC-120, clean twin, Marshall Stack, MesaBoogie, Vox AC30, etc), and speaker cabinets. It also includes a large variety of effects, including delay, chorus, wah, tremelo, reverb, phaser, compressor/limiter, flanger, and a few others. The fun doesn't stop their though. The technology is possible because the unit captures the sound of each individual string. As such, instaneous pitch shifting can be done on a per-string basis. Drop-D, Open-E, Open-G, Open-D, all at the push of button with no returning required. Custom tunnings are also possible. Each string can be adjusted +/- 24 semi-tones, allowing you to also emulate basses, or have the bottom two strings bass, top four strings a 335 f-hole.<br />
|}<br />
There are loads of other features that I haven't even begun to talk about. Auto-harominzing, the ability to adjust the order of the DSP chain, various synth-like sounds, organ sounds, the ability to mix live guitar and synth guitar, the list just goes on. With the version 2 software, it's damn near perfect. The thing sounds damn accurate and in my opinion is the single best piece of equipment a guitarist could ever own (except maybe a guitar :D ). The best part about the unit is the ability to emulate classic setup's for covers bands. I've got patches on here for Clapton, Gary Moore, Santana, Mark Knopfler, Hank Marvin, No Doubt, Sweet Home Alabama... every classic song is covered and sounds damn close to the original recording. You just find out what gear they used, match it as close as possible, and adjust the EQ settings, it's that simple (although does take a lot of time to get right).<br />
<br />
The VG-88 has a Roland EV-5 expression pedal connected to it. The pedal has been modified to include a switch at the toe end (just like wah-wah pedals). I use the pedal for all sorts of things, wah-wah, b-bender on the tele, drive control, adjusting EQ settings on the fly, octave pitch-shifting, etc.<br />
<br />
The whole unit is connected to the power-amp (the VG-88 providing the pre-amps) of a Peavy Studio Pro 112. It's a cheapish amp, but it's loud, solid (it can be thrown around), and it has a decent power-amp and speaker combination. It's almost perfect for the VG-88. Keyboard amps or a PA-System are about the only things that can top my amp for VG-88 use.<br />
<br />
<br />
== Computer Setup ==<br />
* AMD Athlon 64 3500+<br />
* MSI Neo Platinum 2<br />
* ATI X800XTPE<br />
* Creative Audigy 2 Platinum (much to my cottempt, I wan't to get a Digi 002 Rack for recording stuff)<br />
* Western Digital 36 Gig 10,000 RPM drive<br />
* Pioneer DVR-108 DVD Burner<br />
* LiteOn 52327S CD Burner<br />
* Mitsubishi DiamondPlus 93SB 19" Flat Screen Monitor<br />
* Logitech MX700 Mouse & Logitech Cordless Keyboard<br />
* Apple iPod 4G 20GB<br />
<br />
System is currently running Windows XP MCE 2005 with a HDTV Tuner installed. I plan to build a new box, and transfer the tuner card to it and move it onto my DLP projector (90" screen).</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Adobe_AuditionAdobe Audition2005-08-14T09:11:33Z<p>Kl33per: Added some information from Adobe's website; article still a stub</p>
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<div>'''Adobe Audition''' is a Digital Audio Editor released by [http://www.adobe.com Adobe Systems]. Formerly known as Cool Edit Pro, the editor was purchased in [http://www.adobe.com/special/products/audition/syntrillium.html May, 2003.] It is a powerful tool for creating audio for any destination, from CD and DVD, to broadcast television and digital media.<br />
<br />
==Features==<br />
Adobe Audition includes many advanced audio editing features.<br />
===Multi-track Editing===<br />
Adobe Audition is a multi-track editing program with support for up to 128 tracks. You can work in multi-track view, or edit individual waveforms. Audition also has tools for adding audio effects, and creating muisc with loops. It can record up to 32 tracks simultaneously with real-time effects and EQ processing on each track.<br />
===Video Soundtrack Editing===<br />
Audition includes features that make it easy to edit video soundtracks. Included is a video viewer and associated timeline for frame accurate audio editing. File format support includes [[AVI]], native DV, [[MPEG]], and [[WMV]].<br />
===Digital Signal Processing===<br />
Audition features approximately built-in audio processors and effects. Some of these include volume, noise and EQ filters, delay effects, reverb effects, and time/pitch shifting. Audition also supports third-party effects via both the DirectX interface and the VST plug-in architecture.<br />
===High Resolution Audio===<br />
Audition offers audio recording and editing at a variety of quality levels. It supports 32-bit audio with a sample rate of up to 10MHz. Standard sample rates (such as 44.1KHz - CD quality, 48KHz, 92KHz) are also available.<br />
===Other Features===<br />
* CD Burning Support<br />
* 5000 Included Music Loops<br />
* Built-In 5.1 Surround Sound Encoder<br />
<br />
==System Requirements==<br />
* 400MHz or faster processor (2GHz or faster recommended)<br />
* Microsoft® Windows® 2000 or Windows XP Professional or Home Edition<br />
* 64MB of RAM (512MB or more recommended)<br />
* 75MB of available hard-disk space (700MB recommended for installing optional audio clips)<br />
* 800x600 color display (1,024x768 display recommended)<br />
* Stereo sound card (multitrack sound card recommended)<br />
* CD-ROM drive<br />
* CD-RW drive for audio CD creation<br />
* Microsoft DirectX 9.0 software required for video import<br />
* Speakers or headphones recommended<br />
* Microphone (optional)<br />
<br />
==External Links==<br />
* [http://www.adobe.com/products/audition/main.html Official Website]<br />
* [http://www.vuplayer.com/other.php FLAC Filter] Allows Audition to save and edit [[FLAC]] files<br />
<br />
{{Stub}}</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=WavPackWavPack2005-08-14T08:12:06Z<p>Kl33per: </p>
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<div>'''WavPack''' is a free, open source [[lossless]] audio compression format developed by David Bryant.<br />
<br />
<br />
==Description==<br />
<br />
WavPack allows users to compress (and restore) both all [[PCM]] audio formats including 8, 16, and 24-bit ints; 32-bit floats; [[mono]], [[stereo]], and [[multichannel]]; [[sampling rate]]s from 6 to 192 kHz. Like other lossless compression schemes the data reduction varies with the source, but it is generally between 25% and 50% for typical popular music and somewhat better than that for classical music and other sources with greater dynamic range.<br />
<br />
WavPack also incorporates a unique "hybrid" mode that provides all the advantages of lossless compression with an additional bonus. Instead of creating a single file, this mode creates both a relatively small, high-quality lossy file that can be used all by itself, and a "correction" file that (when combined with the lossy file) provides full lossless restoration. For some users this means never having to choose between lossless and lossy compression!<br />
<br />
==Feature Summary==<br />
<br />
* Fast and efficient encoding and decoding<br />
* [[Open source]], released under a BSDish license<br />
* Multiplatform<br />
* Hardware support<br />
* Error robustness<br />
* Streaming support<br />
* Supports multichannel audio and high resolutions<br />
* Hybrid/lossy mode<br />
* Tagging support ([[ID3v1]], [[APE]])<br />
* Supports [[RIFF]] chunks<br />
* Supports embedded CUE sheets<br />
* Includes MD5 hashes for quick integrity checking<br />
* Ability to create self extracting files for Win32 platform<br />
* [[ReplayGain]] compatible<br />
<br />
<br />
==History==<br />
<br />
David Bryant started development on WavPack in mid-1998, with the release of version 1.0. This first version compressed and decompressed audio losslessly, nothing else, but by then it already featured one of the best efficiency vs. speed ratio among lossless encoders. <br />
<br />
Very soon after the release of version 1.0, Bryant released v. 2.0, which featured lossy encoding (using only quantization for data reduction - no psychoacoustic process was applied to the stream).<br />
<br />
In 1999, the developer released version 3.0, which featured novelties such as a fast mode (with reduced compression ratio), compression of RAW files and error detection using CRC checksums.<br />
<br />
WavPack development is still going on, and a major feature added in late 3.x versions is the hybrid mode, where the encoder generates a lossy file + a correction file, so that both can be decompressed back to the original PCM stream.<br />
<br />
WavPack 4 has been recently released. It included important changes, such as fast seeking, multichannel support, high resolution audio support, etc. turning it into one of the most full featured and modern lossless audio compressors.<br />
<br />
<br />
==Software support==<br />
<br />
===Players===<br />
* NullSoft [[Winamp]] (plugin w/ ReplayGain & Media Library support) and Winamp-compatible players<br />
* [[foobar2000]] Advanced Audio Player (official encoding/decoding addon, w/ ReplayGain & Cuesheets support)<br />
* [http://www.vuplayer.com/vuplayer.htm VUPlayer] (official plugin, supports encoding)<br />
* [[Windows Media Player]] and other directshow-based players (MPC, TCMP, RadLight) (with [http://corewavpack.corecodec.org/ CoreWavPack] directshow filter)<br />
* [http://koti.welho.com/hylinen/apollo/ Apollo] Audio Player (plugin w/ ReplayGain support)<br />
* [http://www.un4seen.com/xmplay.html XMplay] (official plugin)<br />
* [http://cogosx.sourceforge.net/ Cog] Audio player for MacOS X.<br />
* [[XMMS]] (with Kuniklo's plugin)<br />
* [http://fondriest.frederic.free.fr/realisations/lamip/ LAMIP] (official plugin)<br />
* [http://mpxplay.net/ MPXplay] for DOS!<br />
<br />
<br />
===Frontends===<br />
* Custom [http://members.home.nl/w.speek/wavpack.htm Windows Frontend] (by Speek)<br />
* [http://www.unifront.boereck.de/ UniversalFront] by Böreck<br />
* [http://home.vxu.se/mdati00/frontah/ Frontah] by Madah<br />
* [http://mareo.monkeydev.org/ Mareo] by Kwambis<br />
<br />
<br />
===Converters===<br />
'''Note:''' ''Several players, like foobar2000 and VUplayer, can also convert from other formats to WavPack)''<br />
* [http://www.dbpoweramp.com/ dBpowerAMP] Music Converter / Audio Player / CD Writer (official addon)<br />
* [http://www.board-24.de/ GX:Transcoder] Music converter<br />
<br />
<br />
===Editors===<br />
* [[Adobe Audition]] and Cool Edit (filter w/ 32-bit floats & extra info save support)<br />
<br />
<br />
===CD writers/rippers===<br />
* [http://www.ahead.de Ahead Nero Burning Rom]<br />
* [http://www.burrrn.net Burrrn] Audio CD burner<br />
* [[Exact Audio Copy]] CD Ripper<br />
* [http://cdexos.sourceforge.net CDex] CD ripper<br />
<br />
<br />
===Taggers===<br />
* [http://www.mp3tag.de/en/index.html Mp3tag] Universal Tag Editor<br />
* [http://users.otenet.gr/~jtcliper/tgf/ The GodFather] Tagger / Music manager<br />
* [http://www.saunalahti.fi/cse/files/Tag.zip Case's Tag] command line tagger<br />
<br />
<br />
===Other tools===<br />
* [http://www.burrrn.net/mrq/ Mr. QuestionMan]<br />
* [http://www.bitattack.ro/ai/ Audio Identifier]<br />
* [http://www.bunkus.org/videotools/mkvtoolnix/ mkvtoolnix] - tool to multiplex WavPack streams inside the Matroska container<br />
It's worth mentioning the [[Matroska]] guys decided to concentrate on WavPack as the <br />
lossless compressor of choice for their container. Quite an honor... :-)<br />
<br />
<br />
==Hardware Support==<br />
<br />
* iRiver iHP-120/iHP-140 with the open source Rockbox firmware<br />
* [http://www.rokulabs.com/products/photobridge/features.php Roku PhotoBridge HD] (w/ [http://www.wavpack.com/downloads.html plugin])<br />
<br />
<br />
==Technology description==<br />
<br />
To ensure high-speed operation, WavPack uses a very simple predictor that is implemented entirely in integer math. In its "fast" mode the prediction is simply the arithmetic extrapolation of the previous two samples. For example, if the previous two samples were -10 and 20, then the prediction would be 50. For the default mode a simple adaptive factor is added to weigh the influence of the earlier sample on the prediction. In our example the resulting prediction could then vary between 20 for no influence to 50 for full influence. This weight factor is constantly updated based on the audio data's changing spectral characteristics, which is why it is called "adaptive". <br />
<br />
The prediction generated is then subtracted from the actual sample to be encoded to generate the error value. In mono mode this value is sent directly to the coder. However, stereo signals tend to have some correlation between the two channels that can be further exploited. Therefore, two error values are calculated that represent the difference and average of the left and right error values. In the "fast" mode of operation these two new values are simply sent to the coder instead of the left and right values. In the default mode, the difference value is always sent to the coder along with one of the other three values (average, left, or right). An adaptive algorithm continuously determines the most efficient of the three to send based on the changing balance of the channels.<br />
<br />
The developer has developed a unique data encoder for WavPack that he believes is better than Rice coding in two different areas. It is impossible to encode more efficiently than Rice coding because it represents the optimal bit coding (sometimes known as the Huffman code) for this type of data. WavPack's encoder is slightly less efficient than this, but only by about 0.15 bits/sample (or less than 1% for 16-bit data). The first advantage of WavPack's coder is that it does not require the data to be buffered ahead of encoding, instead it converts each sample directly to bitcodes. This is more computationally efficient and it is better in some applications where coding delay is critical. The second advantage is that it is easily adaptable to lossy encoding because all significant bits (except the implied "one" MSB) are transmitted directly. In this way it is possible to only transmit, for example, the 3 most significant bits (with sign) of each sample. In fact, it is possible to transmit only the sign and implied MSB for each sample with an average of only 3.65 bits/sample. <br />
<br />
This coding scheme is used to implement the "lossy" mode of WavPack. In the "fast" mode the output of the non-adaptive decorrelator is simply rounded to the nearest codable value for the specified number of bits. In the default mode the adaptive decorrelator is used (which reduces the average noise about 1 dB) and also both the current and the next sample are considered in choosing the better of the two available codes (which reduces noise another 1 dB).<br />
<br />
The developer has decided to not use any floating-point arithmetic in WavPack's data path because he believes that integer operations are less susceptible to subtle chip to chip variations that could corrupt the lossless nature of the compression, the Pentium floating point bug being a blatant example of this. It is possible that a lossless compressor that used floating-point math could generate different output when running on that faulty Pentium. Even disregarding actual bugs, floating-point math is complicated enough that there could be subtle differences between "correct" implementations that could cause trouble for this type of application. To further ensure confidence in the integrity of WavPack's compression, the encoder includes a 32-bit error detection code to the generated streams.<br />
<br />
<br />
WavPack source code is very portable. It has been compiled on several Unices (Linux, Mac OS X, Solaris, FreeBSD, OpenBSD, NetBSD, Compaq Tru64, HP-UX...) as well as Windows and DOS. It works on architectures such as x86, ARM, PowerPC, SPARC, DEC Alpha, PA-RISC, MIPS, Motorola 68k...<br />
<br />
<br />
==Further reading==<br />
<br />
* [http://www.wavpack.com/ Official website]<br />
* [http://www.rarewares.org/lossless.html Unofficial multiplatform versions] at RareWares<br />
* [http://www.rjamorim.com/rrw/wavpack.html Historical versions] at ReallyRareWares<br />
* [[Lossless_comparison|Lossless Codec Comparison]] by Rjamorim<br />
* [[EAC_and_WavPack | Configuring EAC and Wavpack]]</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Topic_IndexTopic Index2005-08-14T08:11:04Z<p>Kl33per: </p>
<hr />
<div>* Please see [http://www.hydrogenaudio.org/forums/index.php?showtopic=12979&st=25&p=247441&#entry247441 this thread] for a discussion of the future structure of this wiki. If you have thoughts, comments, suggestions, etc., please join in this discussion. In the meantime, please feel free to fill in gaps in the information below.<br />
* See also [http://www.hydrogenaudio.org/forums/index.php?showtopic=28658 style related discussion]<br />
<br />
<br />
==General Information==<br />
<br />
===General Guides===<br />
* [[Create a long-term archive]]<br />
* [[Enabling DMA]]<br />
===EAC Guides=== <br />
* [[Create a lossless back-up with EAC and Flac]]<br />
* [[EAC and Lame | Configuring EAC and Lame]]<br />
* [[EAC_and_Ogg_Vorbis | Configuring EAC and Vorbis]]<br />
* [[EAC_and_WavPack | Configuring EAC and Wavpack]]<br />
* [[EAC_and_Flac | Configuring EAC and FLAC]]<br />
* [[EAC_and_Monkeys_Audio | Configuring EAC and Monkey's Audio]]<br />
<br />
===CDex Guides===<br />
===MP3 Guides===<br />
<br />
* [http://wiki.hydrogenaudio.org/index.php?title=LAME Recommended settings for encoding with LAME]<br />
<br />
===Ogg Vorbis Guides=== <br />
<br />
* [http://wiki.hydrogenaudio.org/index.php?title=Recommended_Ogg_Vorbis Recommended encoders and settings for encoding with Vorbis].<br />
<br />
==Audio Codecs==<br />
<br />
===[[Lossy]]===<br />
*[[AAC]]<br />
*[[AC3]]<br />
*[[ATRAC3]]<br />
*[[DTS]]<br />
*[[MP2]]<br />
*[[MP3]]<br />
*[[Musepack]]<br />
*[[Ogg Vorbis]]<br />
*[[QDesign]]<br />
*[[VQF]]<br />
*[[WMA]]<br />
<br />
===[[Lossless]]===<br />
<br />
*[[ALAC|Apple Lossless]]<br />
*[[FLAC|Free Lossless Audio Compressor]]<br />
*[[LA|Lossless Audio]]<br />
*[[LPAC]]<br />
*[[Monkey's Audio]]<br />
*[[OptimFROG]]<br />
*[[RealAudio Lossless]]<br />
*[[Shorten]]<br />
*[[TTA|True Audio]]<br />
*[[WavPack]]<br />
*[[WMA|WMA Lossless]]<br />
<br />
===[[Metadata]] (Tags)===<br />
* [[APEv1]]<br />
* [[APEv2]]<br />
* [[ID3v1]]<br />
* [[ID3v1.1]]<br />
* [[ID3v2]]<br />
* [[Vorbis Comment]]<br />
<br />
==Media Extractors==<br />
<br />
===CD Extractors===<br />
<br />
* [[Exact_Audio_Copy|Exact Audio Copy]] (Win32)<br />
* [[iTunes]] (Win32/OsX)<br />
* [[CDex]] (Win32)<br />
* [[cdparanoia]] (Posix)<br />
* [[Grip]] (Posix) <br />
* [[PlexTools]] (Win32)<br />
* [[dBpowerAMP with AccurateRip]] (Win32)<br />
<br />
===DVD Extractors===<br />
* [[DVDDecrypter]] (Win32)<br />
<br />
<br />
==Media Players==<br />
<br />
=== Windows ===<br />
<br />
* [[Apollo]]<br />
<br />
* [[dBpowerAMP]]<br />
<br />
* [[Foobar2000:Foobar2000|foobar2000]]<br />
<br />
* [[iTunes]]<br />
<br />
* [[musikCube]]<br />
<br />
* [[Quintessential Player]]<br />
<br />
* [[VUplayer]]<br />
<br />
* [[Winamp]]<br />
<br />
* [[Windows Media Player]]<br />
<br />
* [[wxMusik]]<br />
<br />
* [[XMPlay]]<br />
<br />
===Linux/BSD===<br />
<br />
* [[Amarok]]<br />
<br />
* [[BMP]]<br />
<br />
* [[JuK]]<br />
<br />
* [[LAMIP]]<br />
<br />
* [[Muine]]<br />
<br />
* [[Music Player Daemon (MPD)]]<br />
<br />
* [[Rhythmbox]]<br />
<br />
* [[wxMusik]]<br />
<br />
* [[XMMS]]<br />
<br />
===Mac OS X (Non-BSD Specific) ===<br />
<br />
* [[iTunes]]<br />
<br />
* [[skiTunes]]<br />
<br />
* [[Whamb]]<br />
<br />
===Other===<br />
<br />
* [[CL-Amp]] (BeOS)<br />
<br />
<br />
==Audio Editors==<br />
<br />
=== Windows ===<br />
<br />
* [[Adobe_Audition|Adobe Audition]] (Previously known as Cool Edit)<br />
* [[Audacity]]<br />
* [[Goldwave]]<br />
<br />
===Linux/BSD===<br />
<br />
* [[Audacity]]<br />
* [[ReZound]]<br />
<br />
===Mac OS X (Non-BSD Specific) ===<br />
<br />
* [[Audacity]]<br />
<br />
===Other===<br />
<br />
<br />
==Testing Software==<br />
<br />
===Subjective Perceptual===<br />
<br />
* [[ABC/HR]]<br />
<br />
* [[PCABX]]<br />
<br />
===Objective===<br />
<br />
''Note: Might be good to put something here about the problems of quality comparisons using graphs, frequency sweeps, etc.''<br />
<br />
* [[EAQUAL]]<br />
<br />
* [[Rightmark_Audio_Analyzer|Rightmark Audio Analyzer]]<br />
<br />
<br />
==Audio Hardware==<br />
<br />
===PC Audio===<br />
<br />
*[[Terratec EWX 24/96]]<br />
*[[M-Audio Audiophile 24/96]]<br />
*[[M-Audio Revolution 5.1]] <br />
*[[Emu 0404 24/96]] <br />
*[[Emu 1212M 24/192]]<br />
*[[Audiotrak MAYA 5.1]] <br />
*[[Audiotrak Prodigy 7.1]]<br />
<br />
===Notebook Audio=== <br />
*[[Echo Indigo IO 24/96]]<br />
<br />
===HiFi===<br />
<br />
===Digital Audio Players===<br />
<br />
'''Portable Flash'''<br />
<br />
''(These players make use of a internal flash drive.)''<br />
<br />
* [[Creative MuVo]]<br />
<br />
* [[iRiver iFP Series]]<br />
<br />
* [[MPIO lFP Series]]<br />
<br />
* [[Rio Carbon]]<br />
<br />
* [[Neuros]]<br />
<br />
* [[Apple iPod shuffle]]<br />
<br />
'''Portable HD'''<br />
<br />
''(These players make use of a internal harddrive.)''<br />
<br />
* [[Apple iPod]]<br />
<br />
* [[iRiver H-Series]]<br />
<br />
* [[MPIO H-Series]]<br />
<br />
* [[Rio Karma]]<br />
<br />
* [[iAudio M3]]<br />
<br />
* [[Neuros]]<br />
<br />
* [[Archos Jukebox with Rockbox Software]]<br />
<br />
'''Portable CD'''<br />
<br />
'''Car Players'''<br />
<br />
''(Car stereos that can read MP3, Vorbis, WMA, etc.).''<br />
<br />
* [[Aiwa CDC-MP3]]<br />
<br />
==Audio Theory==<br />
<br />
===Analog Audio===<br />
<br />
===Digital Audio===<br />
* [[Replaygain]]<br />
<br />
===Testing Methodology===<br />
<br />
* [[ABX]]<br />
* [[EAQUAL]]<br />
<br />
==Audio Development==<br />
<br />
===Getting Started===<br />
''note: Let's start with basic development tools (compilers, engineering tools, dev. libraries) until we think of more tools to add. I am also adding external links to books, tutorials, etc under resources.''<br />
<br />
===Tools===<br />
<br />
* [http://www.mathworks.com/products/matlab/ MATLAB 7.0] commercial software for algorithmic design, developement, engineering, and scientific computing.<br />
* [http://www.octave.org/ GNU Octave] open-source alternative software (GPL) to MATLAB for numerical computations, engineering, and scientific computing. (multi-platform support)<br />
* [http://www.fftw.org/ FFTW] Is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions on real and complex inputs.<br />
* [http://gcc.gnu.org/ GCC] THE GNU compiler collection for C, C++, Objective-C, Fortran, Java, and Ada.<br />
* [http://www.bloodshed.net/devcpp.html DevCPP] free front-end IDE and compiler for the C and C++ languages. Delphi and C source code available.<br />
<br />
===Resources===<br />
<br />
* [http://www.hydrogenaudio.org/forums/index.php?showforum=30 Scientific/R&D Forums] for Psychoacoustic, DSP, Electrical Engineering, theory, and coding related questions. (most questions are generally answered)<br />
* [http://www.aes.org/ AES] The Audio Engineering Society website. Home of year-round world AES conferences.<br />
* [http://www.dspguru.com/info/books/favor.htm DSP Tutorials] this site provides another good introduction in to the area of DSP. <br />
* [http://www.musicdsp.org/archive.php?classid=2 Music-DSP] source-code archive for anaylsis, filters, effects and synthesis. (C, C++, and Java code)<br />
* [http://www.alsa-project.org/ ALSA Project] (Advanced Linux Sound Architecture) bringing audio and MIDI capabilities to Linux.<br />
* [http://perso.wanadoo.fr/polyvalens/clemens/wavelets/wavelets.html A Really friendly guide to Wavelets] A good introduction to wavelets aimed towards engineer, requires a fair amount of background knowledge.<br />
<br />
===Books/Research=== <br />
* [http://www.springeronline.com/sgw/cda/frontpage/0,11855,5-0-22-1437236-0,00.html?referer=www.springer.de%2Fcgi-bin%2Fsearch_book.pl%3Fisbn%3D3-540-65063-6 Psychoacoustics - Facts and Models] author's Zwicker, Fastl, and Hugo, revised 1999 second edition. THE book for comprehensive psychoacoustics models and figures. <br />
* [http://www.dspguide.com/ Scientist and Engineer's Guide to DSP] author Steve Smith, a great guide for beginners new to the subject of DSP (free online text)<br />
* [http://www.eas.asu.edu/~spanias/papers/paper-audio-tedspanias-00.pdf Perceptual Audio Coding] authors A. Painter and T. Spanias. Comprehensive paper on percepual audio coding (PDF)<br />
<br />
==Audio Resources==<br />
<br />
===Websites===<br />
<br />
''Note: Let's include a small description to the side for now, so that we have something to work with when this section becomes large enough for its own page''<br />
<br />
* http://www.audiocoding.com (Page with a wiki on technical audio topics, homepage of FAAC and FAAD2, also has an AAC forum.)<br />
* http://www.ff123.net (Lots of general information on various MP3 implementations, test samples, testing methodology information, homepage of ABC/HR)<br />
* http://www.head-fi.org (general information/board about head phones and portable audio players)<br />
* http://www.rarewares.org (Downloads for many audio and media tools)<br />
<br />
===Articles===<br />
<br />
===Listening Tests===<br />
* [http://www.rjamorim.com/test/ Roberto's listening tests]<br />
* [http://www.hydrogenaudio.org/forums/index.php?showtopic=35438&st=0 Guruboolez listening test]<br />
<br />
==Other Topics==<br />
<br />
===Video===<br />
<br />
* [[MPEG-4 Visual]]<br />
* [[Theora]]<br />
* [[Real Video]]<br />
* [[Windows Media Video]]<br />
* [[VP6]]<br />
<br />
===[[Container format]]s===<br />
* [[AVI]]<br />
* [[MP4]]<br />
* [[MOV]]<br />
* [[ASF]]<br />
* [[Matroska]]<br />
* [[Ogg]]<br />
<br />
==Glossary==<br />
<br />
* [[Glossary_Of_Audio_Terms|Glossary of Audio Terms]]</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Free_Lossless_Audio_CodecFree Lossless Audio Codec2005-08-14T08:10:15Z<p>Kl33per: Updated Cool Edit to Adobe Audition</p>
<hr />
<div>=What is FLAC?=<br />
<br />
Grossly oversimplified, FLAC is similar to [[MP3]], but [[lossless]], meaning that audio is compressed in FLAC without any loss in quality. This is similar to how Zip works, except with FLAC you will get much better compression because it is designed specifically for audio, and you can play back compressed FLAC files in your favorite player (or your car or home stereo, see supported devices) just like you would an MP3 file.<br />
<br />
FLAC stands for Free Lossless Audio Codec. "Free" means "Free" - that the specification of the stream format is in the public domain. It also means that the sources for libFLAC and libFLAC++ are available under the BSD (Berkeley Software Distribution)<br />
<br />
FLAC compiles on many platforms. <br />
<br />
Some claim FLAC is the most widely used lossless compression format on UNIX systems (though it seems more likely that shn retains that honor on all OS platforms).<br />
<br />
FLAC files can be placed inside an Ogg container using libOggFLAC and libOggFLAC++. <br />
<br />
==Pros==<br />
* Portable to many systems<br />
* Source open and freely licenced<br />
* Hardware support (PhatBox, Kenwood MusicKeg, Rio Karma, etc. See below)<br />
* Streaming support<br />
* Extremely fast decoding<br />
* Supports multichannel and high resolution streams<br />
* Supports [[ReplayGain]]<br />
* Supports cue-sheet (with some limitations)<br />
* Gaining wide use as successor to [[Shorten]]<br />
<br />
==Cons==<br />
* Compresses less efficiently than other popular modern compressors ([[Monkey's Audio]], [[OptimFROG]])<br />
* Higher compression modes slow, for little gain over the default setting.<br />
<br />
=Players that support FLAC=<br />
For a more complete list see the [http://flac.sourceforge.net/links.html FLAC links page].<br />
==Hardware==<br />
===Home stereo===<br />
* [http://www.request.com/us/ AudioReQuest] music servers<br />
* Digital Techniques' "iStereo" [http://www.digitaltechniques.com/M300A_Overview.html M300A Digital Music Player]<br />
* Escient's [http://www.escient.com/ FireBall servers (E2-40/160/300, DVDM-300)]<br />
* [http://www.hermstedt.com/english/hifidelio/hifidelio.html Hifidelio]<br />
* Meda Systems' [http://www.medainc.com/ Bravo servers]<br />
* The [http://www.cesweb.org/attendees/show_floor/product_locator/product_details.asp?prodid=5181 MS300 Music Server] by McIntosh Laboratory<br />
* Olive's [http://www.olive.us/ Symphony] wireless digital music center<br />
* [http://www.phatnoise.com/products/homeplayer/index.php PhatNoise Home Digital Media Player]<br />
* [http://www.mock.com/receiver/ Rio Reciever] and Dell Digital Audio Receiver<br />
* [http://www.rokulabs.com/products/photobridge/features.php Roku PhotoBridge HD] (with [http://homepage.ntlworld.ie/p.mc.quillan/FLAC_V0.7.zip plugin])<br />
* [http://www.skipjam.com/ SkipJam]'s networked audio/video devices<br />
* [http://www.sonos.com/ Sonos Digital Music System]<br />
* [http://www.slimdevices.com/ Squeezebox2]<br />
* [http://www.z500series.com/ Zensonic Z500 Networked DVD Media Player]<br />
<br />
===Car stereo===<br />
* [http://www.phatnoise.com/products/digitalmediaplayers/kenwood_music_keg.php Kenwood Music Keg]<br />
* [http://www.phatnoise.com/products/digitalmediaplayers/index.php PhatBox]<br />
<br />
===Portable===<br />
* [[Rio Karma]]<br />
* [[iAudio M3]] and X5<br />
* iRiver iHP-120/iHP-140 with the open source Rockbox firmware<br />
<br />
==Software==<br />
<br />
===Players===<br />
* [http://koti.welho.com/hylinen/apollo/ Apollo]<br />
* [[foobar2000]]<br />
* [[JRiver Media Center]]<br />
* [http://fondriest.frederic.free.fr/realisations/lamip/ LAMIP]<br />
* [http://www.mplayerhq.hu/ MPlayer]<br />
* [http://www.mythtv.org/ MythTV]<br />
* [http://www.quinnware.com/ QCD] ([http://www.quinnware.com/list_plugins.php?type=input plugin])<br />
* [http://www.videolan.org/ VLC]<br />
* [http://www.vuplayer.com/vuplayer.htm VUPlayer]<br />
* [[Winamp]]<br />
* [[Windows Media Player]] and other directshow-based players (MPC, TCMP, RadLight) (with [http://www.illiminable.com/ogg/ Illiminable's directshow filters] or [http://corecodec.org/projects/coreflac CoreFLAC])<br />
* [http://xine.sourceforge.net/ Xine]<br />
* [[XMMS]]<br />
* [http://www.un4seen.com/ XMplay]<br />
<br />
===Frontends (Windows) ===<br />
* [http://www.uninformative.com/flacattack/ Flacattack]<br />
* Custom [http://members.home.nl/w.speek/flac.htm Windows Frontend] (by Speek)<br />
* [http://www.unifront.boereck.de/ UniversalFront] by Böreck<br />
* [http://home.vxu.se/mdati00/frontah/ Frontah] by Madah<br />
* [http://mareo.monkeydev.org/ Mareo] by Kwambis<br />
<br />
===Frontends (Mac) ===<br />
* [http://www.danrules.com/macflac/ MacFLAC]<br />
* [http://members.rogers.com/beamsplitter/ RipBeak]<br />
* [http://www.versiontracker.com/dyn/moreinfo/macosx/21952 xACT]<br />
<br />
===Converters===<br />
* [http://www.dbpoweramp.com/ dBpowerAMP] Music Converter / Audio Player / CD Writer<br />
* [http://www.germanixsoft.de/ GX:Transcoder] Music converter<br />
<br />
===Editors===<br />
* [[Adobe Audition]]<br />
<br />
===CD writers/rippers===<br />
* [http://www.ahead.de Ahead Nero Burning Rom]<br />
* [http://arson.sourceforge.net/ Arson]<br />
* [http://www.burnatonce.com/ burnatonce]<br />
* [http://www.burrrn.net Burrrn] Audio CD burner<br />
* [[Exact Audio Copy]] CD Ripper<br />
* [http://cdexos.sourceforge.net CDex] CD ripper<br />
* [http://www.cdwave.com/ CD Wave]<br />
<br />
===Taggers===<br />
* [http://www.mp3tag.de/en/index.html Mp3tag] Universal Tag Editor<br />
* [http://users.otenet.gr/~jtcliper/tgf/ The GodFather] Tagger / Music manager<br />
* [http://www.saunalahti.fi/cse/files/Tag.zip Case's Tag] command line tagger<br />
<br />
===Other tools===<br />
* [http://www.burrrn.net/mrq/ Mr. QuestionMan]<br />
* [http://www.bitattack.ro/ai/ Audio Identifier]<br />
* [http://www.bunkus.org/videotools/mkvtoolnix/ mkvtoolnix] - tool to multiplex FLAC streams inside the Matroska container<br />
<br />
<br />
...and many more; see the [http://flac.sourceforge.net/links.html#software FLAC software section] and [http://flac.sourceforge.net/download.html#extras download section] for a more comprehensive list.<br />
<br />
=Frequently Asked Questions=<br />
<br />
''Question:'' Does the compression level affect decompression speed?<br />
<br />
''Short Answer'': No.<br />
<br />
''Long Answer'': In truth, the compression level does affect the decompression speed, but the difference between the various compress levels can barely be measured and is too small to be noticed, even on low-end machines.<br />
<br />
<br />
''Question:'' What is the best compression level for encoding my music?<br />
<br />
''Short Answer'': The default setting, 5.<br />
<br />
''Long Answer'': Encoding at the default setting will give the best balance between compression and encoding speed. Encoding at 8 can more than quadruple the encoding time, while having an insignificant effect on compression.<br />
<br />
See also: [http://flac.sourceforge.net/faq.html FLAC FAQ]<br />
<br />
=Addtional Reading=<br />
* [http://flac.sourceforge.net FLAC Project Webpage]<br />
* [http://flac.sourceforge.net/download.html Download]<br />
* [http://www.digitalnetworksna.com/shop/_templates/item_main_Rio.asp?model=261 Rio Karma]<br />
* [http://members.home.nl/w.speek/comparison.htm Speek's Comparison of lossless audio compressors]<br />
* [[Lossless comparison|Lossless Codec Comparison]] by Rjamorim<br />
* [http://people.ucsc.edu/~rswilson/flactest Omion's FLAC "File Size vs. Decoding Speed" test] - a very thorough test on [[FLAC#Frequently_Asked_Questions|the influence of the chosen encoding level on the decoding speed of FLAC]]; the only one so far to have covered FLAC's --super-secret-totally-impractical-compression-level to this extent as well.</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Frequency_analysisFrequency analysis2005-08-14T08:09:06Z<p>Kl33per: Updated Cool Edit link to Adobe Audition</p>
<hr />
<div>;Why Shouldn't We Use Frequency or Spectral Graphs to Compare Audio Codecs?<br />
<br />
# You can't know precisely what is audible and what is not audible just by looking graphs.<br />
# [[FFT]] [[frequency]] response graphs are rough and can't tell practically anything about the temporal (short time) accuracy.<br />
# All psychoacoustic models are different. What can look good in graphs, doesn't necessarely sound too good and vice versa.<br />
# Graphical analysis is often useful, but only when used together with listening testing. The most useful view is the sound spectra view (spectral view in [[Adobe Audition]]).<br />
# Blind listening testing ([[ABX]]) is the only method that can really be justified when testing quality. Blind testing, when enough propability is reached, is not affected by anykind of bias or placebo.<br />
# Difference/substraction/inverse-mixing method is not conlusive either<br />
<br />
* [http://www.hydrogenaudio.org/index.php?act=ST&f=1&t=4734 More discussion]<br />
* [http://www.hydrogenaudio.org/index.php?act=ST&f=1&t=754 More discussion]<br />
* [http://www.hydrogenaudio.org/index.php?act=ST&f=15&t=7834 More discussion]</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Foobar2000:Encouraged_Tag_StandardsFoobar2000:Encouraged Tag Standards2005-05-15T17:24:49Z<p>Kl33per: </p>
<hr />
<div>== General Tag Construction ==<br />
<br />
* Avoid the use of underscores. Spaces are easier to type, more legible, and as easily useable in Tagz. Spaces are also preferable to no spaces.<br />
* Use an easily understood English field name.<br />
* Prefix album-related information with "ALBUM ", ie. "ALBUM ARTIST", "ALBUM SUBTITLE".<br />
* Avoid use of non-alphabetical characters. For serial fields (for a bad example, FIELD1, FIELD2, etc.), merely enter them in the order that you wish them to be read in.<br />
<br />
== Overview of Current Recommendations ==<br />
<br />
FIELD NAME [format] (component)<br />
<br />
* ALBUM ARTIST [e.g., Various Artists, The Foobar Collective] (none)<br>''Notes'': Field name is ALBUM ARTIST, with ''no underscore''. Tag should exist if and only if an album is by multiple artists, and be contained in every track. Track-specific artists should be entered in the ARTIST tag, never in the TITLE tag.<br>[http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#ALBUM_ARTIST (more about this standard)]<br />
* FIRST_PLAYED and LAST_PLAYED [2005-03-22 19:00:00...] ([http://www.hydrogenaudio.org/forums/index.php?showtopic=20719 foo_playcount])<br>''Notes'': These two tags use underscores instead of spaces - reason for this was to make it consistent with the already existing PLAY_COUNTER-tag. Any amount or type of data may be placed after the time. Compliant TAGZ code shall use $substr() instead of $right() when extracting substrings from this field.<br>''See also'': [http://wiki.hydrogenaudio.org/index.php?title=Foobar2000#Standardize_my_PLAY_DATE_and_PLAY_TIME_fields Standardize my PLAY_DATE and PLAY_TIME fields]<br>[http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#FIRST_PLAYED_and_LAST_PLAYED (more about this standard)]<br />
<br />
=== ALBUM ARTIST ===<br />
''Basics'':<br />
*the tag-fieldname used for declaring and describing albums/split-EPs or split-singles which contain various artists is "ALBUM ARTIST" (seperated with space, not underscore)<br />
*tag should only exist if an album contains various artists. It should NOT be created when an album does not contain various artists.<br />
*the tag can contain the overall artist of an album(like i.e. "the foo-bar collective"), multiple artists(i.e. with split-EPs) or if an album does not have a clear overall artist (for example with compilations) just "Various Artists". Simply said: you're free to enter whatever you like as long as it describes the overall album-wide artist(s).<br />
*every track in a V.A.-album has to contain this tag with the same value<br />
*the track-specific artist should be entered into the ARTIST-tag<br />
*the TITLE-tag should only contain the track-title<br />
<br />
''Reasons for this standard'':<br />
*it solves all issues regarding albums which contain multiple artists with just one tag<br />
*it is already in widespread use<br />
*sortable and searchable with low effort<br />
*keeping the ARTIST-tag trackspecific allows to find tracks in V.A.-albums as well when searching for a certain artist (DB-friendly)<br />
*keeping the TITLE-tag title-specific allows sorting and searching of V.A.-albums by title (DB-friendly)<br />
*allows meaningful determination and display of V.A.-Albums with a minimum amount of code<br />
*avoids resource-hungry and unsafe "guessing" of V.A.-albums via the filepath<br />
*easy to remember and type in manually<br />
*does not disrupt existing systems when the ARTIST- and TITLE-tag are already trackspecific (easy transition)<br />
*can coexist with additional directory-based sorting and marking<br />
*can be used for split-EPs and split-singles as well<br />
<br />
''Code snippets'':<br />
<br />
// check if an album is V.A.<br />
$if(%album artist%,$puts(album_is_va,1))<br />
<br />
// For sorting by artist in an album-context replace %artist% - %album% with:<br />
$if2(%album artist%,%artist%) - %album%<br />
<br />
// singlemode display without %album artist%-support<br />
[%artist% - ][%album% - ][%title%]<br />
// singlemode display with %album artist%-support<br />
// note: if your display supports both, albummode and singlemode, then you<br />
// may want to use the above version instead in singlemode - depends on taste<br />
[$if2(%album artist%,%artist%) - ][%album% - ]$if(%album artist%,[%artist% - ])[%title%]<br />
<br />
// How to easily integrate %album artist% into an albummode-display:<br />
// in the albummode-column, replace %artist% with:<br />
$if2(%album artist%,[%artist%])<br />
// in the title-column, replace %title% with:<br />
$if(%album artist%,[%artist% - ])[%title%]<br />
<br />
=== FIRST_PLAYED and LAST_PLAYED ===<br />
''Basics'':<br />
* the tag-fieldname used for storing info when a song was played the last time is "LAST_PLAYED"<br />
* tag contains date and time in the following format at the beginning: "YYYY-MM-DD HH:MM:SS" (with 24hours-format)<br />
* additional info may be appended after the above info<br />
<br />
''Reasons for this standard'':<br />
* the [http://www.hydrogenaudio.org/musepack/klemm/www.personal.uni-jena.de/~pfk/mpp/sv8/time.html APE-dateformat] (derived from ISO) is internationally neutral<br />
* sortable<br />
* easily readable and recognizable<br />
* format can be verified with TAGZ<br />
* can be included in formatting-strings without reformatting it (pro for amateur tagz-coders)<br />
* choosing a new fieldname avoids confusion with the existing ambigious play_date tag<br />
* field name is easy to understand/recognize/remember and short enough to type in manually<br />
<br />
''Code snippets'':<br />
<br />
// verify tag-format (we check the pos. of the first dash and ":")<br />
// using $len for verification is strongly unrecommended!<br />
$if(<br />
$and($strcmp($strstr(%last_played%,-),5),$strcmp($strstr(%last_played%,:),14))<br />
,$puts(last_played_is_valid,1)<br />
)<br />
<br />
// disassemble the timestamp for later reformatting or calcuations<br />
$puts(last_played_year,$substr(%last played%,1,4))<br />
$puts(last_played_month,$substr(%last played%,6,7))<br />
$puts(last_played_day,$substr(%last played%,9,10))<br />
$puts(last_played_hour,$substr(%last played%,12,13))<br />
$puts(last_played_min,$substr(%last played%,15,16))<br />
$puts(last_played_sec,$substr(%last played%,18,19))<br />
<br />
// display only the date of last_played (without reformatting)<br />
$left(%last_played%,10)<br />
<br />
// display only the time of last_played (without reformatting)<br />
// the use of $right is strongly unrecommended!<br />
$substr(%last_played%,12,19)<br />
<br />
The above code-snippets can be used for FIRST_PLAYED as well(just replace last_played with first_played).<br />
<br />
== Obsolete and Deprecated Tag Standards ==<br />
<br />
=== PLAY_DATE and PLAY_TIME ===<br />
<br />
Deprecated tags produced by old versions of foo_playcount. Default format DDMMYY for PLAY_DATE and HHMMSS (24hr) for PLAY_TIME. See [http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#LAST_PLAYED LAST_PLAYED].</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Foobar2000:Encouraged_Tag_StandardsFoobar2000:Encouraged Tag Standards2005-05-15T17:24:08Z<p>Kl33per: </p>
<hr />
<div>== General Tag Construction ==<br />
<br />
* Avoid the use of underscores. Spaces are easier to type, more legible, and as easily useable in Tagz. Spaces are also preferable to no spaces.<br />
* Use an easily understood English field name.<br />
* Prefix album-related information with "ALBUM ", ie. "ALBUM ARTIST", "ALBUM SUBTITLE".<br />
* Avoid use of non-alphabetical characters. For serial fields (for a bad example, FIELD1, FIELD2, etc.), merely enter them in the order that you wish them to be read in.<br />
<br />
== Overview of Current Recommendations ==<br />
<br />
FIELD NAME [format] (component)<br />
<br />
* ALBUM ARTIST [e.g., Various Artists, The Foobar Collective] (none)<br>''Notes'': Field name is ALBUM ARTIST, with ''no underscore''. Tag should exist if and only if an album is by multiple artists, and be contained in every track. Track-specific artists should be entered in the ARTIST tag, never in the TITLE tag.<br>[http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#ALBUM_ARTIST (more about this standard)]<br />
* FIRST_PLAYED and LAST_PLAYED [2005-03-22 19:00:00...] ([http://www.hydrogenaudio.org/forums/index.php?showtopic=20719 foo_playcount])<br>''Notes'': These two tags use underscores instead of spaces - reason for this was to make it consistent with the already existing PLAY_COUNTER-tag. Any amount or type of data may be placed after the time. Compliant TAGZ code shall use $substr() instead of $right() when extracting substrings from this field.<br>''See also'': [http://wiki.hydrogenaudio.org/index.php?title=Foobar2000#Standardize_my_PLAY_DATE_and_PLAY_TIME_fields Standardize my PLAY_DATE and PLAY_TIME fields]<br>[http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#FIRST_PLAYED_and_LAST_PLAYED (more about this standard)]<br />
<br />
=== ALBUM ARTIST ===<br />
''Basics'':<br />
*the tag-fieldname used for declaring and describing albums/split-EPs or split-singles which contain various artists is "ALBUM ARTIST" (seperated with space, not underscore)<br />
*tag should only exist if an album contains various artists. It should NOT be created when an album does not contain various artists.<br />
*the tag can contain the overall artist of an album(like i.e. "the foo-bar collective"), multiple artists(i.e. with split-EPs) or if an album does not have a clear overall artist (for example with compilations) just "Various Artists". Simply said: you're free to enter whatever you like as long as it describes the overall album-wide artist(s).<br />
*every track in a V.A.-album has to contain this tag with the same value<br />
*the track-specific artist should be entered into the ARTIST-tag<br />
*the TITLE-tag should only contain the track-title<br />
<br />
''Reasons for this standard'':<br />
*it solves all issues regarding albums which contain multiple artists with just one tag<br />
*it is already in widespread use<br />
*sortable and searchable with low effort<br />
*keeping the ARTIST-tag trackspecific allows to find tracks in V.A.-albums as well when searching for a certain artist (DB-friendly)<br />
*keeping the TITLE-tag title-specific allows sorting and searching of V.A.-albums by title (DB-friendly)<br />
*allows meaningful determination and display of V.A.-Albums with a minimum amount of code<br />
*avoids resource-hungry and unsafe "guessing" of V.A.-albums via the filepath<br />
*easy to remember and type in manually<br />
*does not disrupt existing systems when the ARTIST- and TITLE-tag are already trackspecific (easy transition)<br />
*can coexist with additional directory-based sorting and marking<br />
*can be used for split-EPs and split-singles as well<br />
<br />
''Code snippets'':<br />
<br />
// check if an album is V.A.<br />
$if(%album artist%,$puts(album_is_va,1))<br />
<br />
// For sorting by artist in an album-context replace %artist% - %album% with:<br />
$if2(%album artist%,%artist%) - %album%<br />
<br />
// singlemode display without %album artist%-support<br />
[%artist% - ][%album% - ][%title%]<br />
// singlemode display with %album artist%-support<br />
// note: if your display supports both, albummode and singlemode, then you<br />
// may want to use the above version instead in singlemode - depends on taste<br />
[$if2(%album artist%,%artist%) - ][%album% - ]$if(%album artist%,[%artist% - ])[%title%]<br />
<br />
// How to easily integrate %album artist% into an albummode-display:<br />
// in the albummode-column, replace %artist% with:<br />
$if2(%album artist%,[%artist%])<br />
// in the title-column, replace %title% with:<br />
$if(%album artist%,[%artist% - ])[%title%]<br />
<br />
=== FIRST_PLAYED and LAST_PLAYED ===<br />
''Basics'':<br />
* the tag-fieldname used for storing info when a song was played the last time is "LAST PLAYED"<br />
* tag contains date and time in the following format at the beginning: "YYYY-MM-DD HH:MM:SS" (with 24hours-format)<br />
* additional info may be appended after the above info<br />
<br />
''Reasons for this standard'':<br />
* the [http://www.hydrogenaudio.org/musepack/klemm/www.personal.uni-jena.de/~pfk/mpp/sv8/time.html APE-dateformat] (derived from ISO) is internationally neutral<br />
* sortable<br />
* easily readable and recognizable<br />
* format can be verified with TAGZ<br />
* can be included in formatting-strings without reformatting it (pro for amateur tagz-coders)<br />
* choosing a new fieldname avoids confusion with the existing ambigious play_date tag<br />
* field name is easy to understand/recognize/remember and short enough to type in manually<br />
<br />
''Code snippets'':<br />
<br />
// verify tag-format (we check the pos. of the first dash and ":")<br />
// using $len for verification is strongly unrecommended!<br />
$if(<br />
$and($strcmp($strstr(%last_played%,-),5),$strcmp($strstr(%last_played%,:),14))<br />
,$puts(last_played_is_valid,1)<br />
)<br />
<br />
// disassemble the timestamp for later reformatting or calcuations<br />
$puts(last_played_year,$substr(%last played%,1,4))<br />
$puts(last_played_month,$substr(%last played%,6,7))<br />
$puts(last_played_day,$substr(%last played%,9,10))<br />
$puts(last_played_hour,$substr(%last played%,12,13))<br />
$puts(last_played_min,$substr(%last played%,15,16))<br />
$puts(last_played_sec,$substr(%last played%,18,19))<br />
<br />
// display only the date of last_played (without reformatting)<br />
$left(%last_played%,10)<br />
<br />
// display only the time of last_played (without reformatting)<br />
// the use of $right is strongly unrecommended!<br />
$substr(%last_played%,12,19)<br />
<br />
The above code-snippets can be used for FIRST_PLAYED as well(just replace last_played with first_played).<br />
<br />
== Obsolete and Deprecated Tag Standards ==<br />
<br />
=== PLAY_DATE and PLAY_TIME ===<br />
<br />
Deprecated tags produced by old versions of foo_playcount. Default format DDMMYY for PLAY_DATE and HHMMSS (24hr) for PLAY_TIME. See [http://wiki.hydrogenaudio.org/index.php?title=Foobar2000_Encouraged_Tag_Standards#LAST_PLAYED LAST_PLAYED].</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Advanced_Audio_CodingAdvanced Audio Coding2004-12-16T14:30:00Z<p>Kl33per: Updated FAQ to reflect guruboolez's latest tests</p>
<hr />
<div>=Introduction=<br />
'''AAC''' or 'Advanced Audio Coding' forms part of the latest specifications from the MPEG committee, and is their official successor to the popular [[MP3]] format. As with [[MP3]], the '''AAC''' format is an international standard, and is backed by several big-name companies, including Dolby, Sony and Nokia.<br />
<br />
With the 8 <small>(this is just a guess)</small> years that had passed since the creation of the [[MP3]] format, many improvements had been realised leading to a seemingly complex specification with several flavours of '''AAC''' available. To potentially add to the confusion, '''AAC''' is usually wrapped inside an [[MP4]] container to provide tagging, seeking and possibly other benefits?? For this reason, '''AAC''' can also be referred to as [[MP4]] audio.. <br />
<br />
There are several '''AAC''' encoders to choose from, coming from large names such as Apple and Ahead (Creators of Nero - Burning Rom), or the open source F'''AAC''' which is analogous to the [[LAME]] encoder. '''AAC''' is supported on many hardware players, and is available in online stores.. <br />
<br />
In terms of quality, it outperforms [[MP3]] by a nice margin, being on par with OGG and other great codecs, and with '''AAC-HE''' provide the best low bitrate quality.<br />
<br />
<br />
==Pros==<br />
<br />
* An international standard approved by the [http://www.iso.ch ISO]<br />
* Flexible: supports several [[sampling rate]]s (8000-96000 Hz), bit depths, and [[multichannel]] (up to 48 channels)<br />
* Several implementations, including a free and high quality one ([http://www.itunes.com iTunes])<br />
* Reaches transparency in most samples and for most users at around 150kbps<br />
* Part of MPEG4 specs<br />
* Fast decoding (using [http://www.audiocoding.com FAAD])<br />
* Anyone can create it's own implementation (Specifications and demo sources available)<br />
* Some portable players support it (Philips Expanium, iPod, cell phones from Nokia)<br />
<br />
<br />
==Cons==<br />
<br />
* Problem cases that trip out all transform codecs<br />
* Relatively slow encoding<br />
* Heavily patented<br />
* Increased complexity<br />
* '''AAC''' comes in different "flavors" (object types: '''AAC LC''', '''AAC HE''', '''AAC PS''' etc.). Many (especially portable) players only support LC (at the moment) so you can have files that are valid but your player won't play them.<br />
<br />
=Technical Information=<br />
'''AAC''' stands for 'Advanced Audio Coding' and is part of the MPEG-4 Systems Standard. Originally known as MPEG-2 Non-Backwards Compatible (As apposed to MPEG-2 Backwards Compatible) it is the succesor to MPEG-1/2 Layer III ([[MP3]]). It uses the [[MP4]] [[container]] (which is based on Apple's MOV [[container]]) to store metadata (i.e. tag information).<br />
<br />
As part of the MPEG-4 Systems Standard, an '''AAC''' encoded file can include up to 48 full-bandwith audio <br />
channels (up to 96 kHz) and 15 Low Frequency Enhancement channels (limited to 120 Hz) plus 15 data streams.<br />
<br />
'''AAC''' encoding methods are organised into Profiles (MPEG-2) or Object Types (MPEG-4). These different Object Types are not necessarily compatible with each other and may not be playable with various decoders. The various Object Types are:<br />
<br />
* MPEG-2 AAC LC / Low Complexity<br />
* MPEG-2 AAC Main<br />
* MPEG-2 AAC SSR / Scalable Sampling Rate<br />
* MPEG-4 AAC LC / Low Complexity<br />
* MPEG-4 AAC Main<br />
* MPEG-4 AAC SSR / Scalable Sampling Rate<br />
* MPEG-4 AAC LTP / Long Term Prediction<br />
* MPEG-4 AAC HE / High Efficiency<br />
* MPEG-4 AAC LD / Low Delay<br />
<br />
Different Object Types vary in complexity. Some take longer to encode/decode as a result of the different complexities. Furthermore, the benefits of the more complex profiles are often not worth the CPU power required to encode/decode them. As a result the Low Complexity/LC Object Type has become the profile used by most encoders. However, the High Efficiency Object Type has become more popular recently with its addition to the Nero '''AAC''' encoder which now supports HE '''AAC''' encoding.<br />
<br />
Currently all players support the LC Object Type. Players based on the FAAD2 decoder (eg. foobar2000, <br />
Winamp Plugins) support almost all Object Types including HE '''AAC'''. 3ivX also supports all Object Types <br />
except SSR.<br />
<br />
<br />
==Technologies used for compression==<br />
<br />
* [[Huffman coding]]<br />
* [[Quantization]] and scaling<br />
* [[Joint stereo|M/S matrixing]]<br />
* [[Intensity stereo]]<br />
* Channel coupling<br />
* Backward adaptive prediction<br />
* Temporal Noise Shaping (TNS)<br />
* Modified Discrete Cosine Transform (I[[MDCT]])<br />
* Gain control and hybrid filter bank (polyphase quadrature filter (IPQF)+IMDCT)<br />
* Long Term Predictor (LTP) - MPEG4 '''AAC''' only<br />
* Perceptual Noise Substitution (PNS) - MPEG4 '''AAC''' only<br />
* Spectral Band Replication ([[SBR]]) - HE '''AAC'''<br />
* Parametric Stereo (PS) - HE '''AAC'''<br />
<br />
<br />
=Encoders=<br />
There are several encoders listed at [[AAC implementations]].<br />
<br />
<br />
=Decoders=<br />
* [[FAAD]]<br />
<br />
<br />
=FAQ=<br />
<br />
==Great, so you've given me all the technical stuff, but what is AAC really?==<br />
AAC is the culmination of the current state of the art audio encoding techniques. It is designed <br />
to improve upon and replace [[MP3]] as the defacto Audio Encoding standard. It usually offers (depending on <br />
the codec) equivalent quality to [[MP3]] at a lower bitrate.<br />
<br />
==What is the difference between *.[[MP4]] and *.M4A?==<br />
Besides the extension, absolutely nothing. Apple came up with extension to distiguish between files with <br />
Video and Audio (the [[MP4]] extension) and files with Audio only (the M4A extension). As far as the internal <br />
structure of the file, nothing is different.<br />
<br />
==What MPEG 4 extensions does the Apple iPod Accept?==<br />
The iPod accepts files with the [[MP4]] extension, the M4A extension, the M4P extension (a [[Protected AAC]] file), and the M4B extension for audiobook files (which can be either protected or unprotected). It will not accept unwrapped AAC files (files with the .AAC extension).<br />
<br />
==What is the difference between LC (Low Complexity) and HE (High Efficiency)?==<br />
These are two of the various Object Types in the MPEG4 Systems Standard. LC is the most popular Object Type <br />
with all encoders/decoders supporting it. Currently, Nero, Coding Technolgies, and Panasonic have incorporated <br />
the HE '''AAC''' standard into their encoders, which allows for higher quality sound at lower bitrates then the LC <br />
Object Type does (at the same bitrate). The HE Object Type is only used for music with a bitrate of less than <br />
~80kbps.<br />
<br />
==What's the best AAC encoder?==<br />
There is no best '''AAC''' encoder as such. It can be said with reasonable confidence (based on guruboolez's last test, <br />
[http://www.hydrogenaudio.org/forums/index.php?showtopic=29924 hear]) that [http://www.nero.com/en/ Nero AAC] is the best '''AAC''' encoder at 128kbps. However, the quality of any encoder is not linear and therefore these results can not be extrapolated to other bitrates. It can also be said with reasonable confidence that both the iTunes encoder and the [http://www.nero.com/en/ Nero '''AAC''' encoder] are 'mature' and should not fail badly on any particular sample at an average bitrate of 128kbps (i.e. Internet Profile for Nero '''AAC''') or above (based on Roberto's listening tests, see bottom). Beyond that, only you can decide through [[ABX]] testing. See the [[Audio format guide]] <br />
for more information. However, that being said, QuickTime/iTunes and Nero '''AAC''' are considered to be the "safe" <br />
encoders if you wish to archive your music collection on your computer.<br />
<br />
==Do AAC encoded files play back gaplessly?==<br />
Gapless playback is not part of the '''AAC''' standard and as such is not mandatory. However, certain companies can <br />
choose to add gapless encoding/decoding if they desire, providing it doesn't break compatibility with previous <br />
decoders. This is what Ahead have done with their Nero '''AAC''' codec. The files get encoded with information that <br />
allows the gap heard between files to be removed. This however is only possible with supported players (currently <br />
these include foobar2000 and Nero ShowTime). Currently Nero '''AAC''' is the only '''AAC''' codec to have gapless encoding/decoding <br />
support.<br />
<br />
==What players can play back AAC music?==<br />
There are now a number of players that can play back this new format. [http://www.foobar2000.org/ foobar2000]<br />
is considered by many to be the most powerful audio player in existence, and it is certainly capable of playing back <br />
'''AAC''' encoded files. Other players include the [http://www.itunes.com iTunes Digital Jukebox], [http://www.winamp.com <br />
Winamp] and [http://www.real.com/ Real Player].<br />
<br />
<br />
=Other links=<br />
Known [[AAC implementations]].<br />
<br />
Read the [[AAC guide]] to learn how to obtain '''AAC'''/[[MP4]] files out of WAV files and CDs.<br />
<br />
Detailed '''AAC''' comparisons can be found at [http://www.rjamorim.com/test/ Roberto's listening tests page].</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=AAC_encodersAAC encoders2004-12-16T14:21:42Z<p>Kl33per: </p>
<hr />
<div>These are some known AAC encoder implementations.<br />
<br />
=Nero AAC=<br />
<br />
A commercial implementation of both LC AAC and HE AAC, Nero AAC is distributed with Nero 6 which incorporates <br />
Nero Digital. Generally accepted to have the highest quality [[VBR]] LC AAC implementation (although QuickTime beat<br />
it in CBR at 128kbps). The codec also features the HE AAC standard for extremely low bitrates. The codec also allows <br />
for multi-channel surround sound encoding. Unfortunately, unlike iTunes, it's not freeware, and requires the acquisition<br />
of the entire Nero 6 suite for usage of the AAC encoder alone.<br />
<br />
==Recomended Nero AAC Presets==<br />
<br />
NOTE: Once a preset has been selected, the "Encoding Quality" option should be changed to the "Fast" mode. Despite the name implying worse quality then high, a test undertaken by guruboolez shows that the "Fast" mode offers significant quality advantages over the "High" (see the test [http://www.hydrogenaudio.org/forums/index.php?showtopic=29924 hear]). In the forthcoming release of Nero AAC 3.0 (or a release soon afterwards), the "Fast" mode will become the default and the high quality mode will be removed.<br />
<br />
===High Quality===<br />
<br />
: - VBR/Stereo - Streaming, 100-120 Kb/s (LC AAC) / Actual bitrate ~150kbps<br />
<br />
===Portable===<br />
<br />
: - VBR/Stereo - Internet, 90-100 Kb/s (LC AAC) / Actual bitrate ~128kbps<br />
<br />
===Small Filesize===<br />
<br />
: - VBR/Stereo - Portable, 50-70 Kb/s (HE AAC) / Actual bitrate ~90kbps<br />
<br />
<br />
The High Quality preset is for the archival of music, while the Small Filesize preset is for internet/streaming <br />
purposes.<br />
<br />
More information can be found in the [ftp://ftp6.nero.com/infosheets/Nero_Digital/db_nerodigital5.pdf Nero Digital PDF]<br />
and on the [http://www.nerodigital.com/ Nero Digital Website].<br />
<br />
<br />
=QuickTime AAC=<br />
<br />
Another commercial AAC implementation, QuickTime AAC is known to be one of the highest quality medium-bitrate [[CBR]] LC <br />
AAC encoders. Whilst the current version only supports 2 channel audio, it is hoped multi-channel support, along with <br />
[[VBR]] encoding will be added in a future version.<br />
<br />
Although this is a comercial implementation and part of the QuickTime Pro package, the codec is available for free <br />
through the [http://www.apple.com/itunes/ iTunes Digital Jukebox]<br />
<br />
Update: It is rumored that the next major version of Apple's codec (included in iTunes 5.0, as a part of iLife 5.0 in Mac OSX Tiger to be released early next year) will support AAC HE & [[VBR]] encoding.<br />
<br />
More information can be found at the [http://www.apple.com/mpeg4/aac/ Apple Website]<br />
<br />
=FAAC=<br />
<br />
FAAC is a free and open-source LC AAC encoder. Its quality has improved drastically over the last few months and <br />
is now a viable alternative to the commercial encoders (although, at least at 128kbps, not as good as the free <br />
iTunes encoder).<br />
<br />
More information can be found at [http://www.audiocoding.com/ AudioCoding]<br />
<br />
=HHI/zPlane (Compaact!)=<br />
<br />
Compaact is one of the newest AAC encoders. Like Nero AAC, compaact is not free, however it does offer an <br />
impressive feature set. Roberto Amorim's last AAC test showed that at 128kbps, Compaact! is tied with both the FAAC <br />
and Coding Technologies (Real) encoders. Compaact! features both the LC and Main Object Types, CBR, VBR, <br />
Multichannel high resolution (24bit/96kHz) encoding, and command line support.<br />
<br />
For portable encoding, try -q5 to -q6. For music archive purposes, try -q7 to -q8.<br />
<br />
More information can be found at the [http://www.compaact.com/aacPage.php?SPRACHE=UK&PAGE=compaact Compaact website].<br />
<br />
<br />
=PsyTEL=<br />
<br />
The creation of Ivan Dimkovic (who now works on Nero AAC), PsyTEL AAC was one of the first AAC encoders. Its <br />
multi-channel support has bugs that make it unusable, but it's 2 channel had the best quality available in its day. <br />
Since the implementation of Nero AAC, this codec has become obselete. It's is now outclassed by both Nero AAC <br />
and iTunes.<br />
<br />
The PsyTEL encoder can be found in the AAC section of [http://www.rjamorim.com/rrw/ ReallyRareWares]<br />
<br />
==Usability (Psytel aacenc/fastenc)==<br />
<br />
; -tape<br />
; -radio<br />
; -internet<br />
; -streaming<br />
; -normal<br />
; -extreme<br />
; -archive<br />
; -ultra<br />
<br />
<br />
For music encoding. The quality ranges from -tape (lowest [VBR] quality) to -ultra (highest [VBR] quality). Ultra <br />
is considered overkill for most audio tracks, i.e: shouldn't be used except for extremely difficult music signals. <br />
Example: aacenc -extreme -if "audio file.wav"<br />
<br />
==Encoder switches (Psytel aacenc/fastenc)==<br />
<br />
; -if <br />
: Input filename. The name of the track to be encoded (must be a .wav file)<br />
<br />
; -of <br />
: Output filename. May be omitted, because encoder will automatically set best output file name.<br />
<br />
; -br <br />
: BitRate switch. Sets the number of bits utilized per second for the encoding process. Example: aacenc -br 192 -if "audio file.wav"<br />
<br />
; -vbrhi <br />
: High quality [VBR] mode. Can be used with -br switch to select base BitRate. If -br is not specified, it takes as default 64kbps/channel. Example: aacenc -br 192 -vbrhi -if "audio file.wav"<br />
<br />
; -vr <br />
: Lower quality [VBR] mode. Recommended for internet streaming. Example: aacenc -vr -if "audio file.wav"<br />
<br />
; -c <br />
: LowPassFilter cut-off (in hertz). Not recommended. Example: aacenc -br 128 -c 15995 -if "audio file.wav"<br />
<br />
; -qual <br />
: Encoder quality level (1 to 9). 9 is usually taken as default, but you can use smaller numbers if you need high speed and high quality isn't essential. Example: aacenc -br 192 -qual 9 -if "audio file.wav"<br />
<br />
; -adif <br />
: Use adif instead of adts (default) header. For compatibility with some decoder software and hardware players. Example: aacenc -br 192 -adif -if "audio file.wav"<br />
<br />
; -nh <br />
: No headers (raw iso aac stream). For decoder compatibility, and can improve. Example: aacenc -br 192 -nh -if "audio file.wav"<br />
<br />
; -profile "x" <br />
: Choose iso aac encoding profile:<br />
:: 0 - low complexity (default, recommended)<br />
:: 1 - main (not recommended, buggy)<br />
:: 2 - main ltp (mpeg-4 only)<br />
<br />
: Only lc profile is playable on hardware players so far. Example: aacenc -br 192 -profile 2 -if "audio file.wav"<br />
<br />
; -ihsc <br />
: Improved human speech coding. Best for human voice encoding. Not recommended for low Bitrates or [CBR] coding. Example: aacenc -vbrhi -br 192 -ihsc -if "audio file.wav"<br />
<br />
; -low_ath <br />
: Tells encoder to use highest sensitivity threshold of audibility. Not recommended on Bitrates lower than 192kbps. Example: aacenc -br 192 -low_ath -if "audio file.wav"<br />
<br />
; -pns <br />
: (perceptual noise substitution) - Improves the quality at very low Bitrates. Should be used only at 64kbps or less. Example: aacenc -br 56 -pns -if "audio file.wav"<br />
<br />
=Imagine=<br />
<br />
Imagine Technology provides an MPEG-4 LC AAC plugin for Adobe Audition. This plugin provides file input and output <br />
for the MPEG-4 audio specification, defined in ISO/IEC 14496-3. More info can be found at the <br />
[http://imaginetechnology.net/plugins.html imagine website].<br />
<br />
<br />
=Coding Technologies=<br />
<br />
RealNetworks has incorporated Coding Technologies’ MPEG-4 AAC / aacPlus™ technology and software within RealNetworks’ <br />
software products. As a result, in the newest version of RealProducer 10, AAC has replaced [[ATRAC]]3 as the high bitrate <br />
audio codec, and that software can encode AAC files wrapped in the RealMedia container. In addition, the Producer<br />
SDK on Windows also includes HE-AAC encoding. More info can be found at <br />
[http://www.realnetworks.com/company/press/releases/2004/codingtech.html RealNetworks' press release], as well as <br />
Coding Technologies' [http://www.codingtechnologies.com/products/aacPlus.htm aacPlus page].<br />
<br />
<br />
=FhG=<br />
<br />
[http://www.iis.fraunhofer.de/amm/techinf/aac/ Audio & Multimedia MPEG-2 AAC]<br />
<br />
<br />
=Emuzed=<br />
<br />
Emuzed develops and sells various products and technologies for the PC multimedia and embedded multimedia markets. <br />
They have ported and optimized codecs for MPEG-4 ASP and AAC LC for a chip vendor preparing to offer bundled <br />
multimedia hardware and software. More info can be found at their [http://www.emuzed.com/encoders.html encoders & decoders]<br />
page.<br />
<br />
<br />
=NEC=<br />
<br />
NEC Corporation has developed an LC AAC decoding algorithm for mobile devices. They have also developed a codec <br />
named MPEG-4 AAC Ext.1, which they claim decreases bitrate while maintaining the same audio quality. The new MPEG-4 <br />
AAC Ext.1 coding technology also supports high compatibility with current MPEG-4 AAC. For more information, see <br />
[http://www.neceurope.com/release.asp?parentid=671&Area=1 NEC's press release].<br />
<br />
<br />
=Panasonic=<br />
<br />
Panasonic has developed a HE AAC codec together with NEC and Coding Technologies as described in <br />
[http://www.telos-systems.com/techtalk/hosted/m4-in-30100%20(M4IF_HE_AAC_paper).pdf this MPEG Industry Forum paper].<br />
<br />
<br />
=Real/Helix Producer=<br />
[[Real Producer|Real/Helix Producer]]: http://helixcommunity.org</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=AAC_encodersAAC encoders2004-12-16T14:21:04Z<p>Kl33per: Change the Nero presets a little, small gramar fixes</p>
<hr />
<div>These are some known AAC encoder implementations.<br />
<br />
=Nero AAC=<br />
<br />
A commercial implementation of both LC AAC and HE AAC, Nero AAC is distributed with Nero 6 which incorporates <br />
Nero Digital. Generally accepted to have the highest quality [[VBR]] LC AAC implementation (although QuickTime beat<br />
it in CBR at 128kbps). The codec also features the HE AAC standard for extremely low bitrates. The codec also allows <br />
for multi-channel surround sound encoding. Unfortunately, unlike iTunes, it's not freeware, and requires the acquisition<br />
of the entire Nero 6 suite for usage of the AAC encoder alone.<br />
<br />
==Recomended Nero AAC Presets==<br />
<br />
NOTE: Once a preset has been selected, the "Encoding Quality" option should be changed to the "Fast" mode. Despite the name implying worse quality then high, a test undertaken by guruboolez shows that the "Fast" mode offers significant quality advantages over the "High" (see the test [http://www.hydrogenaudio.org/forums/index.php?showtopic=29924 hear]). In the forthcoming release of Nero AAC 3.0 (or a release soon afterwards), the "Fast" mode will become the default and the high quality mode will be removed.<br />
<br />
===High Quality===<br />
<br />
: - VBR/Stereo - Streaming, 100-120 Kb/s (LC AAC) / Actual bitrate ~150kbps<br />
<br />
<br />
===Portable===<br />
<br />
: - VBR/Stereo - Internet, 90-100 Kb/s (LC AAC) / Actual bitrate ~128kbps<br />
<br />
===Small Filesize===<br />
<br />
: - VBR/Stereo - Portable, 50-70 Kb/s (HE AAC) / Actual bitrate ~90kbps<br />
<br />
<br />
The High Quality preset is for the archival of music, while the Small Filesize preset is for internet/streaming <br />
purposes.<br />
<br />
More information can be found in the [ftp://ftp6.nero.com/infosheets/Nero_Digital/db_nerodigital5.pdf Nero Digital PDF]<br />
and on the [http://www.nerodigital.com/ Nero Digital Website].<br />
<br />
<br />
=QuickTime AAC=<br />
<br />
Another commercial AAC implementation, QuickTime AAC is known to be one of the highest quality medium-bitrate [[CBR]] LC <br />
AAC encoders. Whilst the current version only supports 2 channel audio, it is hoped multi-channel support, along with <br />
[[VBR]] encoding will be added in a future version.<br />
<br />
Although this is a comercial implementation and part of the QuickTime Pro package, the codec is available for free <br />
through the [http://www.apple.com/itunes/ iTunes Digital Jukebox]<br />
<br />
Update: It is rumored that the next major version of Apple's codec (included in iTunes 5.0, as a part of iLife 5.0 in Mac OSX Tiger to be released early next year) will support AAC HE & [[VBR]] encoding.<br />
<br />
More information can be found at the [http://www.apple.com/mpeg4/aac/ Apple Website]<br />
<br />
=FAAC=<br />
<br />
FAAC is a free and open-source LC AAC encoder. Its quality has improved drastically over the last few months and <br />
is now a viable alternative to the commercial encoders (although, at least at 128kbps, not as good as the free <br />
iTunes encoder).<br />
<br />
More information can be found at [http://www.audiocoding.com/ AudioCoding]<br />
<br />
=HHI/zPlane (Compaact!)=<br />
<br />
Compaact is one of the newest AAC encoders. Like Nero AAC, compaact is not free, however it does offer an <br />
impressive feature set. Roberto Amorim's last AAC test showed that at 128kbps, Compaact! is tied with both the FAAC <br />
and Coding Technologies (Real) encoders. Compaact! features both the LC and Main Object Types, CBR, VBR, <br />
Multichannel high resolution (24bit/96kHz) encoding, and command line support.<br />
<br />
For portable encoding, try -q5 to -q6. For music archive purposes, try -q7 to -q8.<br />
<br />
More information can be found at the [http://www.compaact.com/aacPage.php?SPRACHE=UK&PAGE=compaact Compaact website].<br />
<br />
<br />
=PsyTEL=<br />
<br />
The creation of Ivan Dimkovic (who now works on Nero AAC), PsyTEL AAC was one of the first AAC encoders. Its <br />
multi-channel support has bugs that make it unusable, but it's 2 channel had the best quality available in its day. <br />
Since the implementation of Nero AAC, this codec has become obselete. It's is now outclassed by both Nero AAC <br />
and iTunes.<br />
<br />
The PsyTEL encoder can be found in the AAC section of [http://www.rjamorim.com/rrw/ ReallyRareWares]<br />
<br />
==Usability (Psytel aacenc/fastenc)==<br />
<br />
; -tape<br />
; -radio<br />
; -internet<br />
; -streaming<br />
; -normal<br />
; -extreme<br />
; -archive<br />
; -ultra<br />
<br />
<br />
For music encoding. The quality ranges from -tape (lowest [VBR] quality) to -ultra (highest [VBR] quality). Ultra <br />
is considered overkill for most audio tracks, i.e: shouldn't be used except for extremely difficult music signals. <br />
Example: aacenc -extreme -if "audio file.wav"<br />
<br />
==Encoder switches (Psytel aacenc/fastenc)==<br />
<br />
; -if <br />
: Input filename. The name of the track to be encoded (must be a .wav file)<br />
<br />
; -of <br />
: Output filename. May be omitted, because encoder will automatically set best output file name.<br />
<br />
; -br <br />
: BitRate switch. Sets the number of bits utilized per second for the encoding process. Example: aacenc -br 192 -if "audio file.wav"<br />
<br />
; -vbrhi <br />
: High quality [VBR] mode. Can be used with -br switch to select base BitRate. If -br is not specified, it takes as default 64kbps/channel. Example: aacenc -br 192 -vbrhi -if "audio file.wav"<br />
<br />
; -vr <br />
: Lower quality [VBR] mode. Recommended for internet streaming. Example: aacenc -vr -if "audio file.wav"<br />
<br />
; -c <br />
: LowPassFilter cut-off (in hertz). Not recommended. Example: aacenc -br 128 -c 15995 -if "audio file.wav"<br />
<br />
; -qual <br />
: Encoder quality level (1 to 9). 9 is usually taken as default, but you can use smaller numbers if you need high speed and high quality isn't essential. Example: aacenc -br 192 -qual 9 -if "audio file.wav"<br />
<br />
; -adif <br />
: Use adif instead of adts (default) header. For compatibility with some decoder software and hardware players. Example: aacenc -br 192 -adif -if "audio file.wav"<br />
<br />
; -nh <br />
: No headers (raw iso aac stream). For decoder compatibility, and can improve. Example: aacenc -br 192 -nh -if "audio file.wav"<br />
<br />
; -profile "x" <br />
: Choose iso aac encoding profile:<br />
:: 0 - low complexity (default, recommended)<br />
:: 1 - main (not recommended, buggy)<br />
:: 2 - main ltp (mpeg-4 only)<br />
<br />
: Only lc profile is playable on hardware players so far. Example: aacenc -br 192 -profile 2 -if "audio file.wav"<br />
<br />
; -ihsc <br />
: Improved human speech coding. Best for human voice encoding. Not recommended for low Bitrates or [CBR] coding. Example: aacenc -vbrhi -br 192 -ihsc -if "audio file.wav"<br />
<br />
; -low_ath <br />
: Tells encoder to use highest sensitivity threshold of audibility. Not recommended on Bitrates lower than 192kbps. Example: aacenc -br 192 -low_ath -if "audio file.wav"<br />
<br />
; -pns <br />
: (perceptual noise substitution) - Improves the quality at very low Bitrates. Should be used only at 64kbps or less. Example: aacenc -br 56 -pns -if "audio file.wav"<br />
<br />
=Imagine=<br />
<br />
Imagine Technology provides an MPEG-4 LC AAC plugin for Adobe Audition. This plugin provides file input and output <br />
for the MPEG-4 audio specification, defined in ISO/IEC 14496-3. More info can be found at the <br />
[http://imaginetechnology.net/plugins.html imagine website].<br />
<br />
<br />
=Coding Technologies=<br />
<br />
RealNetworks has incorporated Coding Technologies’ MPEG-4 AAC / aacPlus™ technology and software within RealNetworks’ <br />
software products. As a result, in the newest version of RealProducer 10, AAC has replaced [[ATRAC]]3 as the high bitrate <br />
audio codec, and that software can encode AAC files wrapped in the RealMedia container. In addition, the Producer<br />
SDK on Windows also includes HE-AAC encoding. More info can be found at <br />
[http://www.realnetworks.com/company/press/releases/2004/codingtech.html RealNetworks' press release], as well as <br />
Coding Technologies' [http://www.codingtechnologies.com/products/aacPlus.htm aacPlus page].<br />
<br />
<br />
=FhG=<br />
<br />
[http://www.iis.fraunhofer.de/amm/techinf/aac/ Audio & Multimedia MPEG-2 AAC]<br />
<br />
<br />
=Emuzed=<br />
<br />
Emuzed develops and sells various products and technologies for the PC multimedia and embedded multimedia markets. <br />
They have ported and optimized codecs for MPEG-4 ASP and AAC LC for a chip vendor preparing to offer bundled <br />
multimedia hardware and software. More info can be found at their [http://www.emuzed.com/encoders.html encoders & decoders]<br />
page.<br />
<br />
<br />
=NEC=<br />
<br />
NEC Corporation has developed an LC AAC decoding algorithm for mobile devices. They have also developed a codec <br />
named MPEG-4 AAC Ext.1, which they claim decreases bitrate while maintaining the same audio quality. The new MPEG-4 <br />
AAC Ext.1 coding technology also supports high compatibility with current MPEG-4 AAC. For more information, see <br />
[http://www.neceurope.com/release.asp?parentid=671&Area=1 NEC's press release].<br />
<br />
<br />
=Panasonic=<br />
<br />
Panasonic has developed a HE AAC codec together with NEC and Coding Technologies as described in <br />
[http://www.telos-systems.com/techtalk/hosted/m4-in-30100%20(M4IF_HE_AAC_paper).pdf this MPEG Industry Forum paper].<br />
<br />
<br />
=Real/Helix Producer=<br />
[[Real Producer|Real/Helix Producer]]: http://helixcommunity.org</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=MppencMppenc2004-11-26T04:32:19Z<p>Kl33per: </p>
<hr />
<div></div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Advanced_Audio_CodingAdvanced Audio Coding2004-10-27T07:24:00Z<p>Kl33per: Small grammar update</p>
<hr />
<div>=Introduction=<br />
'''AAC''' or 'Advanced Audio Coding' forms part of the latest specifications from the MPEG committee, and is their official successor to the popular [[MP3]] format. As with [[MP3]], the '''AAC''' format is an international standard, and is backed by several big-name companies, including Dolby, Sony and Nokia.<br />
<br />
With the 8 <small>(this is just a guess)</small> years that had passed since the creation of the [[MP3]] format, many improvements had been realised leading to a seemingly complex specification with several flavours of '''AAC''' available. To potentially add to the confusion, '''AAC''' is usually wrapped inside an [[MP4]] container to provide tagging, seeking and possibly other benefits?? For this reason, '''AAC''' can also be referred to as [[MP4]] audio.. <br />
<br />
There are several '''AAC''' encoders to choose from, coming from large names such as Apple and Ahead (Creators of Nero - Burning Rom), or the open source F'''AAC''' which is analogous to the [[LAME]] encoder. '''AAC''' is supported on many hardware players, and is available in online stores.. <br />
<br />
In terms of quality, it outperforms [[MP3]] by a nice margin, being on par with OGG and other great codecs, and with '''AAC-HE''' provide the best low bitrate quality.<br />
<br />
<br />
==Pros==<br />
<br />
* An international standard approved by the [http://www.iso.ch ISO]<br />
* Flexible: supports several [[sampling rate]]s (8000-96000 Hz), bit depths, and [[multichannel]] (up to 48 channels)<br />
* Several implementations, including a free and high quality one ([http://www.itunes.com iTunes])<br />
* Reaches transparency in most samples and for most users at around 150kbps<br />
* Part of MPEG4 specs<br />
* Fast decoding (using [http://www.audiocoding.com FAAD])<br />
* Anyone can create it's own implementation (Specifications and demo sources available)<br />
* Some portable players support it (Philips Expanium, iPod, cell phones from Nokia)<br />
<br />
<br />
==Cons==<br />
<br />
* Problem cases that trip out all transform codecs<br />
* Relatively slow encoding<br />
* Heavily patented<br />
* Increased complexity<br />
* '''AAC''' comes in different "flavors" (object types: '''AAC LC''', '''AAC HE''', '''AAC PS''' etc.). Many (especially portable) players only support LC (at the moment) so you can have files that are valid but your player won't play them.<br />
<br />
=Technical Information=<br />
'''AAC''' stands for 'Advanced Audio Coding' and is part of the MPEG-4 Systems Standard. Originally known as MPEG-2 Non-Backwards Compatible (As apposed to MPEG-2 Backwards Compatible) it is the succesor to MPEG-1/2 Layer III ([[MP3]]). It uses the [[MP4]] [[container]] (which is based on Apple's MOV [[container]]) to store metadata (i.e. tag information).<br />
<br />
As part of the MPEG-4 Systems Standard, an '''AAC''' encoded file can include up to 48 full-bandwith audio <br />
channels (up to 96 kHz) and 15 Low Frequency Enhancement channels (limited to 120 Hz) plus 15 data streams.<br />
<br />
'''AAC''' encoding methods are organised into Profiles (MPEG-2) or Object Types (MPEG-4). These different Object Types are not necessarily compatible with each other and may not be playable with various decoders. The various Object Types are:<br />
<br />
* MPEG-2 AAC LC / Low Complexity<br />
* MPEG-2 AAC Main<br />
* MPEG-2 AAC SSR / Scalable Sampling Rate<br />
* MPEG-4 AAC LC / Low Complexity<br />
* MPEG-4 AAC Main<br />
* MPEG-4 AAC SSR / Scalable Sampling Rate<br />
* MPEG-4 AAC LTP / Long Term Prediction<br />
* MPEG-4 AAC HE / High Efficiency<br />
* MPEG-4 AAC LD / Low Delay<br />
<br />
Different Object Types vary in complexity. Some take longer to encode/decode as a result of the different complexities. Furthermore, the benefits of the more complex profiles are often not worth the CPU power required to encode/decode them. As a result the Low Complexity/LC Object Type has become the profile used by most encoders. However, the High Efficiency Object Type has become more popular recently with its addition to the Nero '''AAC''' encoder which now supports HE '''AAC''' encoding.<br />
<br />
Currently all players support the LC Object Type. Players based on the FAAD2 decoder (eg. foobar2000, <br />
Winamp Plugins) support almost all Object Types including HE '''AAC'''. 3ivX also supports all Object Types <br />
except SSR.<br />
<br />
<br />
==Technologies used for compression==<br />
<br />
* [[Huffman coding]]<br />
* [[Quantization]] and scaling<br />
* [[Joint stereo|M/S matrixing]]<br />
* [[Intensity stereo]]<br />
* Channel coupling<br />
* Backward adaptive prediction<br />
* Temporal Noise Shaping (TNS)<br />
* Modified Discrete Cosine Transform (I[[MDCT]])<br />
* Gain control and hybrid filter bank (polyphase quadrature filter (IPQF)+IMDCT)<br />
* Long Term Predictor (LTP) - MPEG4 '''AAC''' only<br />
* Perceptual Noise Substitution (PNS) - MPEG4 '''AAC''' only<br />
* Spectral Band Replication ([[SBR]]) - HE '''AAC'''<br />
* Parametric Stereo (PS) - HE '''AAC'''<br />
<br />
<br />
=Encoders=<br />
There are several encoders listed at [[AAC implementations]].<br />
<br />
<br />
=Decoders=<br />
* [[FAAD]]<br />
<br />
<br />
=FAQ=<br />
<br />
==Great, so you've given me all the technical stuff, but what is AAC really?==<br />
AAC is the culmination of the current state of the art audio encoding techniques. It is designed <br />
to improve upon and replace [[MP3]] as the defacto Audio Encoding standard. It usually offers (depending on <br />
the codec) equivalent quality to [[MP3]] at a lower bitrate.<br />
<br />
==What is the difference between *.[[MP4]] and *.M4A?==<br />
Besides the extension, absolutely nothing. Apple came up with extension to distiguish between files with <br />
Video and Audio (the [[MP4]] extension) and files with Audio only (the M4A extension). As far as the internal <br />
structure of the file, nothing is different.<br />
<br />
==What extensions does the Apple iPod Accept?==<br />
The iPod accepts files with both the [[MP4]] extension and the M4A extension. It will not accept unwrapped AAC files <br />
(files with the .AAC extension).<br />
<br />
==What is the difference between LC (Low Complexity) and HE (High Efficiency)?==<br />
These are two of the various Object Types in the MPEG4 Systems Standard. LC is the most popular Object Type <br />
with all encoders/decoders supporting it. Currently, Nero, Coding Technolgies, and Panasonic have incorporated <br />
the HE '''AAC''' standard into their encoders, which allows for higher quality sound at lower bitrates then the LC <br />
Object Type does (at the same bitrate). The HE Object Type is only used for music with a bitrate of less than <br />
~80kbps.<br />
<br />
==What's the best AAC encoder?==<br />
There is no best '''AAC''' encoder as such. It can be said with reasonable confidence (based on Roberto's last test, <br />
see above) that [http://www.quicktime.com QuickTime/iTunes] is the best '''AAC''' encoder at 128kbps. However, the <br />
quality of any encoder is not linear and therefore these results can not be extrapolated to other bitrates. It <br />
can also be said with reasonable confidence that both the iTunes encoder and the [http://www.ahead.com Nero '''AAC''' encoder]<br />
are 'mature' and should not fail badly on any particular sample at an average bitrate of 128kbps (i.e. Internet Profile <br />
for Nero '''AAC''') or above. Beyond that, only you can decide through [[ABX]] testing. See the [[Audio format guide]] <br />
for more information. However, that being said, QuickTime/iTunes and Nero '''AAC''' are considered to be the "safe" <br />
encoders if you wish to archive your music collection on your computer.<br />
<br />
==Do AAC encoded files play back gaplessly?==<br />
Gapless playback is not part of the '''AAC''' standard and as such is not mandatory. However, certain companies can <br />
choose to add gapless encoding/decoding if they desire, providing it doesn't break compatibility with previous <br />
decoders. This is what Ahead have done with their Nero '''AAC''' codec. The files get encoded with information that <br />
allows the gap heard between files to be removed. This however is only possible with supported players (currently <br />
these include foobar2000 and Nero ShowTime). Currently Nero '''AAC''' is the only '''AAC''' codec to have gapless encoding/decoding <br />
support.<br />
<br />
==What players can play back AAC music?==<br />
There are now a number of players that can play back this new format. [http://www.foobar2000.org/ foobar2000]<br />
is considered by many to be the most powerful audio player in existence, and it is certainly capable of playing back <br />
'''AAC''' encoded files. Other players include the [http://www.itunes.com iTunes Digital Jukebox], [http://www.winamp.com <br />
Winamp] and [http://www.real.com/ Real Player].<br />
<br />
<br />
=Other links=<br />
Known [[AAC implementations]].<br />
<br />
Read the [[AAC guide]] to learn how to obtain '''AAC'''/[[MP4]] files out of WAV files and CDs.<br />
<br />
Detailed '''AAC''' comparisons can be found at [http://www.rjamorim.com/test/ Roberto's listening tests page].</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=AAC_encodersAAC encoders2004-10-27T07:23:14Z<p>Kl33per: Added QT AAC Rumor</p>
<hr />
<div>These are some known AAC encoder implementations.<br />
<br />
=Nero AAC=<br />
<br />
A commercial implementation of both LC AAC and HE AAC, Nero AAC is distributed with Nero 6 which incorporates <br />
Nero Digital. Generally accepted to have the highest quality [[VBR]] LC AAC implementation (although QuickTime beat<br />
it in CBR at 128kbps). The codec also features the HE AAC standard for extremely low bitrates. The codec also allows <br />
for multi-channel surround sound encoding. Unfortunately, unlike iTunes, it's not freeware, and requires the acquisition<br />
of the entire Nero 6 suite for usage of the AAC encoder alone.<br />
<br />
==Recomended Nero AAC Presets==<br />
<br />
===High Quality===<br />
<br />
: - VBR/Stereo - Transparent, 110-150 Kb/s (LC AAC)<br />
: - VBR/Stereo - Extreme, 140-190 Kb/s (LC AAC)<br />
<br />
===Portable===<br />
<br />
: - VBR/Stereo - Internet, 90-100 Kb/s (LC AAC)<br />
: - VBR/Stereo - Streaming, 100-120 Kb/s (LC AAC)<br />
<br />
===Small Filesize===<br />
<br />
: - VBR/Stereo - Portable, 50-70 Kb/s (HE AAC)<br />
: - CBR/Stereo - 80 Kb/s (HE AAC)<br />
<br />
<br />
The High Quality presets are for the archival of music, while the Small Filesize presets are for internet/streaming <br />
purposes.<br />
<br />
More information can be found in the [ftp://ftp6.nero.com/infosheets/Nero_Digital/db_nerodigital5.pdf Nero Digital PDF]<br />
and on the [http://www.nerodigital.com/ Nero Digital Website].<br />
<br />
<br />
=QuickTime AAC=<br />
<br />
Another commercial AAC implementation, QuickTime AAC is known to have the highest quality medium-bitrate [[CBR]] LC <br />
AAC encoder. While the current version only supports 2 channel audio, it is hoped multi-channel support, along with <br />
[[VBR]] encoding will be added in a future version.<br />
<br />
Although this is a comercial implementation and part of the QuickTime Pro package, the codec is available for free <br />
through the [http://www.apple.com/itunes/ iTunes Digital Jukebox]<br />
<br />
Update: It is rumored that the next major version of Apple's codec (included in iTunes 5.0, as a part of iLife 5.0 in Mac OSX Tiger to be released early next year) will support AAC HE & [[VBR]] encoding.<br />
<br />
More information can be found at the [http://www.apple.com/mpeg4/aac/ Apple Website]<br />
<br />
=FAAC=<br />
<br />
FAAC is a free and open-source LC AAC encoder. It's quality has improved drastically over the last few months and <br />
is now a viable alternative to the commercial encoders (although, at least at 128kbps, not as good as the free <br />
iTunes encoder).<br />
<br />
More information can be found at [http://www.audiocoding.com/ AudioCoding]<br />
<br />
<br />
=HHI/zPlane (Compaact!)=<br />
<br />
Compaact is one of the newest AAC encoders. Like Nero AAC, compaact is not free, however it does offer an <br />
impressive feature set. Roberto Amorim's last AAC test showed that at 128kbps, Compaact! is tied with both the FAAC <br />
and Coding Technologies (Real) encoders. Compaact! features both the LC and Main Object Types, CBR, VBR, <br />
Multichannel high resolution (24bit/96kHz) encoding, and command line support.<br />
<br />
For portable encoding, try -q5 to -q6. For music archive purposes, try -q7 to -q8.<br />
<br />
More information can be found at the [http://www.compaact.com/aacPage.php?SPRACHE=UK&PAGE=compaact Compaact website].<br />
<br />
<br />
=PsyTEL=<br />
<br />
The creation of Ivan Dimkovic (who now works on Nero AAC), PsyTEL AAC was one of the first AAC encoders. Its <br />
multi-channel support has bugs that make it unusable, but it's 2 channel had the best quality available in it's day. <br />
Since the implementation of Nero AAC, this codec has become obselete. It's is now outclassed by both Nero AAC <br />
and iTunes.<br />
<br />
The PsyTEL encoder can be found in the AAC section of [http://www.rjamorim.com/rrw/ ReallyRareWares]<br />
<br />
==Usability (Psytel aacenc/fastenc)==<br />
<br />
; -tape<br />
; -radio<br />
; -internet<br />
; -streaming<br />
; -normal<br />
; -extreme<br />
; -archive<br />
; -ultra<br />
<br />
<br />
For music encoding. The quality ranges from -tape (lowest [VBR] quality) to -ultra (highest [VBR] quality). Ultra <br />
is considered overkill for most audio tracks, i.e: shouldn't be used except for extremely difficult music signals. <br />
Example: aacenc -extreme -if "audio file.wav"<br />
<br />
==Encoder switches (Psytel aacenc/fastenc)==<br />
<br />
; -if <br />
: Input filename. The name of the track to be encoded (must be a .wav file)<br />
<br />
; -of <br />
: Output filename. May be omitted, because encoder will automatically set best output file name.<br />
<br />
; -br <br />
: BitRate switch. Sets the number of bits utilized per second for the encoding process. Example: aacenc -br 192 -if "audio file.wav"<br />
<br />
; -vbrhi <br />
: High quality [VBR] mode. Can be used with -br switch to select base BitRate. If -br is not specified, it takes as default 64kbps/channel. Example: aacenc -br 192 -vbrhi -if "audio file.wav"<br />
<br />
; -vr <br />
: Lower quality [VBR] mode. Recommended for internet streaming. Example: aacenc -vr -if "audio file.wav"<br />
<br />
; -c <br />
: LowPassFilter cut-off (in hertz). Not recommended. Example: aacenc -br 128 -c 15995 -if "audio file.wav"<br />
<br />
; -qual <br />
: Encoder quality level (1 to 9). 9 is usually taken as default, but you can use smaller numbers if you need high speed and high quality isn't essential. Example: aacenc -br 192 -qual 9 -if "audio file.wav"<br />
<br />
; -adif <br />
: Use adif instead of adts (default) header. For compatibility with some decoder software and hardware players. Example: aacenc -br 192 -adif -if "audio file.wav"<br />
<br />
; -nh <br />
: No headers (raw iso aac stream). For decoder compatibility, and can improve. Example: aacenc -br 192 -nh -if "audio file.wav"<br />
<br />
; -profile "x" <br />
: Choose iso aac encoding profile:<br />
:: 0 - low complexity (default, recommended)<br />
:: 1 - main (not recommended, buggy)<br />
:: 2 - main ltp (mpeg-4 only)<br />
<br />
: Only lc profile is playable on hardware players so far. Example: aacenc -br 192 -profile 2 -if "audio file.wav"<br />
<br />
; -ihsc <br />
: Improved human speech coding. Best for human voice encoding. Not recommended for low Bitrates or [CBR] coding. Example: aacenc -vbrhi -br 192 -ihsc -if "audio file.wav"<br />
<br />
; -low_ath <br />
: Tells encoder to use highest sensitivity threshold of audibility. Not recommended on Bitrates lower than 192kbps. Example: aacenc -br 192 -low_ath -if "audio file.wav"<br />
<br />
; -pns <br />
: (perceptual noise substitution) - Improves the quality at very low Bitrates. Should be used only at 64kbps or less. Example: aacenc -br 56 -pns -if "audio file.wav"<br />
<br />
<br />
=Imagine=<br />
<br />
Imagine Technology provides an MPEG-4 LC AAC plugin for Adobe Audition. This plugin provides file input and output <br />
for the MPEG-4 audio specification, defined in ISO/IEC 14496-3. More info can be found at the <br />
[http://imaginetechnology.net/plugins.html imagine website].<br />
<br />
<br />
=Coding Technologies=<br />
<br />
RealNetworks has incorporated Coding Technologies’ MPEG-4 AAC / aacPlus™ technology and software within RealNetworks’ <br />
software products. As a result, in the newest version of RealProducer 10, AAC has replaced [[ATRAC]]3 as the high bitrate <br />
audio codec, and that software can encode AAC files wrapped in the RealMedia container. In addition, the Producer<br />
SDK on Windows also includes HE-AAC encoding. More info can be found at <br />
[http://www.realnetworks.com/company/press/releases/2004/codingtech.html RealNetworks' press release], as well as <br />
Coding Technologies' [http://www.codingtechnologies.com/products/aacPlus.htm aacPlus page].<br />
<br />
<br />
=FhG=<br />
<br />
[http://www.iis.fraunhofer.de/amm/techinf/aac/ Audio & Multimedia MPEG-2 AAC]<br />
<br />
<br />
=Emuzed=<br />
<br />
Emuzed develops and sells various products and technologies for the PC multimedia and embedded multimedia markets. <br />
They have ported and optimized codecs for MPEG-4 ASP and AAC LC for a chip vendor preparing to offer bundled <br />
multimedia hardware and software. More info can be found at their [http://www.emuzed.com/encoders.html encoders & decoders]<br />
page.<br />
<br />
<br />
=NEC=<br />
<br />
NEC Corporation has developed an LC AAC decoding algorithm for mobile devices. They have also developed a codec <br />
named MPEG-4 AAC Ext.1, which they claim decreases bitrate while maintaining the same audio quality. The new MPEG-4 <br />
AAC Ext.1 coding technology also supports high compatibility with current MPEG-4 AAC. For more information, see <br />
[http://www.neceurope.com/release.asp?parentid=671&Area=1 NEC's press release].<br />
<br />
<br />
=Panasonic=<br />
<br />
Panasonic has developed a HE AAC codec together with NEC and Coding Technologies as described in <br />
[http://www.telos-systems.com/techtalk/hosted/m4-in-30100%20(M4IF_HE_AAC_paper).pdf this MPEG Industry Forum paper].<br />
<br />
<br />
=Real/Helix Producer=<br />
[[Real Producer|Real/Helix Producer]]: http://helixcommunity.org</div>Kl33perhttps://wiki.hydrogenaud.io/index.php?title=Advanced_Audio_CodingAdvanced Audio Coding2004-10-24T12:32:51Z<p>Kl33per: Grammar & Spelling Corrections</p>
<hr />
<div>=Introduction=<br />
'''AAC''' or 'Advanced Audio Coding' forms part of the latest specifications from the MPEG committee, and is their official successor to the popular [[MP3]] format. As with [[MP3]], the '''AAC''' format is an international standard, and is backed by several big-name companies, including Dolby, Sony and Nokia.<br />
<br />
With the 8 <small>(this is just a guess)</small> years that had passed since the creation of the [[MP3]] format, many improvements had been realised leading to a seemingly complex specification with several flavours of '''AAC''' available. To potentially add to the confusion, '''AAC''' is usually wrapped inside an [[MP4]] container to provide tagging, seeking and possibly other benefits?? For this reason, '''AAC''' can also be referred to as [[MP4]] audio.. <br />
<br />
There are several '''AAC''' encoders to choose from, coming from large names such as Apple and Ahead (Creators of Nero - Burning Rom), or the open source F'''AAC''' which is analogous to the [[LAME]] encoder. '''AAC''' is supported on many hardware players, and is available in online stores.. <br />
<br />
In terms of quality, it outperforms [[MP3]] by a nice margin, being on par with OGG and other great codecs, and with '''AAC-HE''' provide the best low bitrate quality.<br />
<br />
<br />
==Pros==<br />
<br />
* An international standard approved by the [http://www.iso.ch ISO]<br />
* Flexible: supports several [[sampling rate]]s (8000-96000 Hz), bit depths, and [[multichannel]] (up to 48 channels)<br />
* Several implementations, including a free and high quality one ([http://www.itunes.com iTunes])<br />
* Reaches transparency in most samples and for most users at around 150kbps<br />
* Part of MPEG4 specs<br />
* Fast decoding (using [http://www.audiocoding.com FAAD])<br />
* Anyone can create it's own implementation (Specifications and demo sources available)<br />
* Some portable players support it (Philips Expanium, iPod, cell phones from Nokia)<br />
<br />
<br />
==Cons==<br />
<br />
* Problem cases that trip out all transform codecs<br />
* Relatively slow encoding<br />
* Heavily patented<br />
* Increased complexity<br />
* '''AAC''' comes in different "flavors" (object types: '''AAC LC''', '''AAC HE''', '''AAC PS''' etc.). Many (especially portable) players only support LC (at the moment) so you can have files that are valid but your player won't play them.<br />
<br />
=Technical Information=<br />
'''AAC''' stands for 'Advanced Audio Coding' and is part of the MPEG-4 Systems Standard. Originally known as MPEG-2 Non-Backwards Compatible (As apposed to MPEG-2 Backwards Compatible) it is the succesor to MPEG-1/2 Layer III ([[MP3]]). It uses the [[MP4]] [[container]] (which is based on Apple's MOV [[container]]) to store metadata (i.e. tag information).<br />
<br />
As part of the MPEG-4 Systems Standard, an '''AAC''' encoded file can include up to 48 full-bandwith audio <br />
channels (up to 96 kHz) and 15 Low Frequency Enhancement channels (limited to 120 Hz) plus 15 data streams.<br />
<br />
'''AAC''' encoding methods are organised into Profiles (MPEG-2) or Object Types (MPEG-4). These different Object Types are not necessarily compatible with each other and may not be playable with various decoders. The various Object Types are:<br />
<br />
* MPEG-2 AAC LC / Low Complexity<br />
* MPEG-2 AAC Main<br />
* MPEG-2 AAC SSR / Scalable Sampling Rate<br />
* MPEG-4 AAC LC<br />
* MPEG-4 AAC Main<br />
* MPEG-4 AAC SSR<br />
* MPEG-4 AAC LTP / Long Term Prediction<br />
* MPEG-4 AAC HE / High Efficiency<br />
* MPEG-4 AAC LD / Low Delay<br />
<br />
Different Object Types vary in complexity. Some take longer to encode/decode as a result of the different complexities. Furthermore, the benefits of the more complex profiles are often not worth the CPU power required to encode/decode them. As a result the Low Complexity/LC Object Type has become the profile used by most encoders. However, the High Efficiency Object Type has become more popular recently with its addition to the Nero '''AAC''' encoder which now supports HE '''AAC''' encoding.<br />
<br />
Currently all players support the LC Object Type. Players based on the FAAD2 decoder (eg. foobar2000, <br />
Winamp Plugins) support almost all Object Types including HE '''AAC'''. 3ivX also supports all Object Types <br />
except SSR.<br />
<br />
<br />
==Technologies used for compression==<br />
<br />
* [[Huffman coding]]<br />
* [[Quantization]] and scaling<br />
* [[Joint stereo|M/S matrixing]]<br />
* [[Intensity stereo]]<br />
* Channel coupling<br />
* Backward adaptive prediction<br />
* Temporal Noise Shaping (TNS)<br />
* Modified Discrete Cosine Transform (I[[MDCT]])<br />
* Gain control and hybrid filter bank (polyphase quadrature filter (IPQF)+IMDCT)<br />
* Long Term Predictor (LTP) - MPEG4 '''AAC''' only<br />
* Perceptual Noise Substitution (PNS) - MPEG4 '''AAC''' only<br />
* Spectral Band Replication ([[SBR]]) - HE '''AAC'''<br />
* Parametric Stereo (PS) - HE '''AAC'''<br />
<br />
<br />
=Encoders=<br />
There are several encoders listed at [[AAC implementations]].<br />
<br />
<br />
=Decoders=<br />
* [[FAAD]]<br />
<br />
<br />
=FAQ=<br />
<br />
==Great, so you've given me all the technical stuff, but what is AAC really?==<br />
AAC is the culmination of the current state of the art audio encoding techniques. It is designed <br />
to improve upon and replace [[MP3]] as the defacto Audio Encoding standard. It usually offers (depending on <br />
the codec) equivalent quality to [[MP3]] at a lower bitrate.<br />
<br />
==What is the difference between *.[[MP4]] and *.M4A?==<br />
Besides the extension, absolutely nothing. Apple came up with extension to distiguish between files with <br />
Video and Audio (the [[MP4]] extension) and files with Audio only (the M4A extension). As far as the internal <br />
structure of the file, nothing is different.<br />
<br />
==What extensions does the Apple iPod Accept?==<br />
The iPod accepts files with both the [[MP4]] extension and the M4A extension. It will not accept unwrapped AAC files <br />
(files with the .AAC extension).<br />
<br />
==What is the difference between LC (Low Complexity) and HE (High Efficiency)?==<br />
These are two of the various Object Types in the MPEG4 Systems Standard. LC is the most popular Object Type <br />
with all encoders/decoders supporting it. Currently, Nero, Coding Technolgies, and Panasonic have incorporated <br />
the HE '''AAC''' standard into their encoders, which allows for higher quality sound at lower bitrates then the LC <br />
Object Type does (at the same bitrate). The HE Object Type is only used for music with a bitrate of less than <br />
~80kbps.<br />
<br />
==What's the best AAC encoder?==<br />
There is no best '''AAC''' encoder as such. It can be said with reasonable confidence (based on Roberto's last test, <br />
see above) that [http://www.quicktime.com QuickTime/iTunes] is the best '''AAC''' encoder at 128kbps. However, the <br />
quality of any encoder is not linear and therefore these results can not be extrapolated to other bitrates. It <br />
can also be said with reasonable confidence that both the iTunes encoder and the [http://www.ahead.com Nero '''AAC''' encoder]<br />
are 'mature' and should not fail badly on any particular sample at an average bitrate of 128kbps (i.e. Internet Profile <br />
for Nero '''AAC''') or above. Beyond that, only you can decide through [[ABX]] testing. See the [[Audio format guide]] <br />
for more information. However, that being said, QuickTime/iTunes and Nero '''AAC''' are considered to be the "safe" <br />
encoders if you wish to archive your music collection on your computer.<br />
<br />
==Do AAC encoded files play back gaplessly?==<br />
Gapless playback is not part of the '''AAC''' standard and as such is not mandatory. However, certain companies can <br />
choose to add gapless encoding/decoding if they desire, providing it doesn't break compatibility with previous <br />
decoders. This is what Ahead have done with their Nero '''AAC''' codec. The files get encoded with information that <br />
allows the gap heard between files to be removed. This however is only possible with supported players (currently <br />
these include foobar2000 and Nero ShowTime). Currently Nero '''AAC''' is the only '''AAC''' codec to have gapless encoding/decoding <br />
support.<br />
<br />
==What players can play back AAC music?==<br />
There are now a number of players that can play back this new format. [http://www.foobar2000.org/ foobar2000]<br />
is considered by many to be the most powerful audio player in existence, and it is certainly capable of playing back <br />
'''AAC''' encoded files. Other players include the [http://www.itunes.com iTunes Digital Jukebox], [http://www.winamp.com <br />
Winamp] and [http://www.real.com/ Real Player].<br />
<br />
<br />
=Other links=<br />
Known [[AAC implementations]].<br />
<br />
Read the [[AAC guide]] to learn how to obtain '''AAC'''/[[MP4]] files out of WAV files and CDs.<br />
<br />
Detailed '''AAC''' comparisons can be found at [http://www.rjamorim.com/test/ Roberto's listening tests page].</div>Kl33per