Hydrogenaudio Knowledgebase - User contributions [en]

Multichannel

2005-03-26T15:12:01Z

62.61.135.181:

'''''Multichannel''''' refers to audio streams with more than two channels. The most usual multichannel setups are 5.1 (five main channels: front center, front right, front left, rear right, rear left and one [[LFE|Low Frequency Extension]] channel) and 6.1 (the five channels from 5.1 + back center).

Formerly limited to movie theaters, multichannel audio has became popular since the introduction of the DVD video format. The two competitors to the title of CD successor, [[DVD-Audio]] and [[SACD]], can also offer multichannel content.

Some formats that support multichannel encoding are: [[AAC]], [[Ogg Vorbis]], [[WMA]] Pro, [[AC3]], [[DTS]], [[FLAC]] and [[Wavpack]].

There's no standard channel mapping for multichannel streams, and each vendor (Microsoft, Dolby, MPEG, Xiph...) creates its own or copies it from another vendor.

Multichannel recordings are often referred to as "Surround".

I prepared some test streams to check if your surround setup speakers are positioned correctly. The AC3 and DTS streams follow the standards set by the developers of such technologies (they were encoded with official encoders). The AAC stream was created with Compaact!, and I can't guarantee all channels will be decoded at their correct places when playing back with different decoders.

In this test, a synthetic voice will say out loud the position where each stream should be coming from.

[http://www.rarewares.org/wiki/files/test.ac3.zip AC3 stream] 101kB

[http://www.rarewares.org/wiki/files/test.dts.zip DTS stream] 136kB

[http://www.rarewares.org/wiki/files/test.m4a AAC stream] 58kB

See also: [[Stereo]], [[Mono]]

CDex

2005-03-26T11:23:09Z

62.61.135.181:

CDex is a tool to do all sorts of things audio related. Mainly focused on ripping and converting, things like turning your home Compact Disc collection into an mp3 collection on your hard drive become extremely easy. With built in support for many encoders you wont find any shortage of options for your media files. Below is a more in-depth explination of CDex features.

'''CDex Feature List'''

* Easy to use interface
* Media File Player
* Create PLS and M3U playlist files
* Advanced jitter correction
* Supports the [http://www.xiph.org/paranoia/index.html cdparanoia] software extraction libraries
* Support for many file formats/audio encoders (WAV, [[MP3]], [[Ogg_Vorbis|OGG]], VQF, [[Monkey%27s_Audio|APE]], etc)
* Support for ID3 V1 and V2 tags
* Support for normalization of audio files
* Support for transcoding of compressed audio files
* Support for CDDB
* Support for recording from the analog input line

Best of all CDex is entirely free! You will never have to pay to use the software or register in any way. Moreover, CDex is entirely opensource, as per the GPL Terms.

=Additional Reading=

* [http://cdexos.sourceforge.net/ CDex homepage]
* [[EAC_Vs_CDex_SecureMode | CDex full paranoia versus EAC secure mode]] (by Pio2001)
* [http://home.iprimus.com.au/alexanderino/cdex/ Jason Antony's CDEX Guide For Beginners]

AAC Guide

2005-03-25T21:19:31Z

62.61.135.181:

=AAC Guide=

The purpose of this guide is helping you create AAC/MP4 files the most easy and quick way possible.

==Ripping from CD directly to AAC==

# Using [[Guide aac itunes ripping|Apple iTunes]]
# Using [[Guide aac cdex|CDex]] + Psytel AACenc or NAACenc
# Using [[Guide aac eac|EAC]] + Psytel AACenc or NAACenc

==Converting from WAV to AAC==
''(to obtain the wavs from CD, check out the [[CDex]] and [[EAC]] guides)''

# Using [[Guide aac itunes|Apple iTunes]]
# Using [[Guide aac nero|Ahead Nero]] (or NAACenc)
# Using [[Guide aac faac|FAAC]]
# Using [[Guide aac psytel|Psytel AACenc and Fastenc]]
# Using [[Guide aac squeeze|Sorenson Squeeze]]

==Converting from other formats to AAC==
''(of course, conversion from lossy formats is never recommended. The idea of this guide is to help people convert from lossless formats)''

# Using [[Guide aac foobar|Foobar2000]] + foo_neroaac
# Using [[Guide aac nero plugins|Ahead Nero]] + Mausau's plugins

==Wrapping AAC streams in MP4==

# Using [[Guide aac mp4ui|MP4ui]]
# Using [[Guide aac mp4creator|MPEG4ip MP4creator]]

==Appendix==

# [[Playback aac|Playing back AAC files]]

Recommended LAME

2005-03-22T08:38:55Z

62.61.135.181:

'''Note: These settings require Lame 3.90 or later. Lame 3.90.3 found on this website is the recommended version''' ([[Lame Compiles|Check here to download]])

''Note: At a given bitrate range, the quality scale usually works to where VBR is higher quality than ABR which is higher quality than CBR (CBR < ABR < VBR in terms of quality). The exception to this is when you choose the highest possible CBR bitrate which is 320kbps. In the case of the named VBR profiles "standard" and "extreme" they are usually "effectively" equal in quality to high bitrate cbr, in the range of around 256 kbps due to their ability to scale down the bitrate when necessary but increase the bitrate beyond 256 kbps on a frame by frame basis also, when that is necessary.''

=Recommended encoder settings=

* --alt-preset standard (~190 kbit/s, typical 180 ... 220. '''Best quality / size ratio''')

* --alt-preset fast standard (~190 kbit/s, faster but potentially lower quality)

* --alt-preset extreme (~250 kbit/s, typical 220 ... 270. Quality can be a little better than standard)

* --alt-preset fast extreme (~250 kbit/s, faster but potentially lower quality)

* --alt-preset insane (320 kbit/s CBR, highest possible quality, that can be a little higher than extreme)

For high quality on portable MP3 players, you may use --alt-preset standard -Y (around 160 kbit/s). -Y usually limits to 16 KHz, something you likely won't notice unless you have an exeptional hearing.

==VBR (Variable bitrate) settings==
[[VBR]] can be useful to get good quality from a specific quality level. Size is less predictable than with ABR, but the quality is usually better.

-V(number) where number is 0-10, 0 being highest quality, 10 being the lowest.

V0 is ~280kbs
V1 is ~250kbs

==ABR (average bitrate) settings==
''(128 kbit/s ABR: roughly the same filesize as 128 kbit/s CBR)''

* '''[[ABR]] Setting tuned from 320 kbit/s down to 80 kbit/s'''
** --alt-preset <bitrate>
:: Example: --alt-preset 200

* '''128 kbit/s ABR'''
** -V5 --athaa-sensitivity 1 (when using >= LAME 3.96.1, for best results at 128kbps)
** --alt-preset 128

:: or (ff123's and Hans' suggestion: http://www.ff123.net/cbr128.html ):
:: --abr 128 -h --nspsytune --athtype 2 --lowpass 16 --ns-bass -8 --scale 0.93

==CBR (constant bitrate) settings==

*'''[[CBR]] Setting tuned from 320 kbit/s down to 80 kbit/s'''
** --alt-preset cbr <bitrate>
:: Example: --alt-preset cbr 96

* '''128 kbit/s CBR'''
** --alt-preset cbr 128

:: or (ff123's and Hans' suggestion: http://www.ff123.net/cbr128.html ):
:: -h --nspsytune --athtype 2 --lowpass 16 --ns-bass -8 --scale 0.93

: note: --alt-preset cbr 320 is the exact same thing as --alt-preset insane

==Additional reading==

[http://www.hydrogenaudio.org/show.php/showtopic/203 List of recommended LAME settings] @ HydrogenAudio forum