Lossless

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Compression is '''lossless''' when decoding the compressed data gives a result which is identical bit-by-bit to the uncompressed original.

Generic file compression formats, like ZIP or RAR, are lossless. However, trying to compress raw audio with those generally results in files which are only slightly- if at all- smaller than the originals. Lossless audio formats take advantage of knowledge about real-world audio data to provide compression ratios averaging around 50% on most music.

[[Lossy]] encoders only attempt to approximate the sound of the original waveform rather than preserving all the information present in it. Losslessly compressed audio will therefore unavoidably be larger than audio compressed with any reasonable [[lossy]] encoder. However, this disadvantage is offset by lossless files' ability to be [[transcoding|transcoded]] to other lossless formats without any quality degradation.

== Popular lossless formats ==
* [[Apple Lossless]] ([[ALAC]])
* [[Free Lossless Audio Codec]] (FLAC)
* [[Lossless Audio]] (LA)
* [[Lossless Predictive Audio Compression]] (LPAC)
* [[Meridian Lossless Packing]] (MLP)
* [[Monkey's Audio]] (APE)
* [[OptimFROG]]
* [[RK Audio]] (RKAU)
* [[Shorten]] (SHN)
* [[TAK]]
* [[TTA]]
* [[WavPack]]
* [[Windows Media Audio|WMA lossless]]

== Oddball Formats ==
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.

Most of those would have disappeared by now, but they are being preserved for posterity at [[User:Rjamorim|rjamorim]]'s

* Advanced Digital Audio (ADA)
* Marian's a-Pac
* AudioZip
* Dakx WAV
* Entis Lab MIO
* LiteWave
* Pegasus SPS
* RKaudio
* Split2000
* Sonarc
* VocPack
* WavArc
* WaveZip/MUSICompress

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.

== Comparisons ==
''Note the specific assumptions and limitations of each comparison; in particular, results are sensitive to the music selected'''

; [[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.

* <s> Performance Comparison of Lossless Audio Compressors [http://members.home.nl/w.speek/comparison.htm here] </s> - Compares file size, encode speed, decode speed for [[APE]], [[FLAC]], [[LPAC]], [[WavPack]], Shorten ([[SHN]]), [[RKAU]], [[OptimFROG]], [[LA]], [[WMA | WMA Lossless]]. Updated 5-2003 => This page is no longer available!

* Lossless audio formats [http://www.bobulous.org.uk/misc/lossless_audio_2006.html here] - A comparison of the rip-and-encode speed and album file size of six different lossless formats: [[WAV|uncompressed Wave]], [[FLAC]], [[WavPack]], [[SHN|Shorten]], [[APE|Monkey's Audio]], and [[OptimFROG]]. First published on 22nd May 2006.

[[Category:Codecs]]

Free Lossless Audio Codec

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{{Codec Infobox
| name = FLAC
| logo = [[Image:FLAC logo.gif]]
| type = lossless
| purpose = Popular open source patent free lossless compression scheme.
| maintainer = Josh Coalson, Xiph Community
| recommended_encoder = FLAC encoder
| recommended_text = FLAC v1.3.1 (25-11-2014)
| website = http://xiph.org/flac/
}}
'''Free Lossless Audio Codec''' ('''FLAC''') is a codec for lossless audio compression.
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, if supported) just like you would a lossy file.

FLAC is supported by default in Android since version 3.1 and in Windows 10.

== General aspects of the format ==
FLAC is freely available and supported on most operating systems, including Windows, UNIX (Linux, *BSD, Solaris, OS X, IRIX), BeOS, OS/2, and Amiga. There are build systems for autotools, MSVC, Watcom C, and Project Builder.

The FLAC project consists of:
* the stream format
* reference encoders and decoders in library form
* flac, a command-line program to encode and decode FLAC files
* metaflac, a command-line metadata editor for FLAC files
* input plugins for various music players

When it's said that FLAC is ''free'', it means more than just that it is available at no cost. It means that the specification of the format is fully open to the public to be used for any purpose, although the FLAC project reserves the right to set the FLAC specification and certify compliance. It also means that neither the FLAC format nor any of the implemented encoding/decoding methods are covered by any known patent. And it means that all the source code is available under [http://xiph.org/flac/license.html open-source licenses]. It is the first truly open and free lossless audio format.

== Features ==
* '''Lossless:''' The encoding of audio (PCM) data incurs no loss of information, and the decoded audio is bit-for-bit identical to what went into the encoder. Each frame contains a 16-bit CRC of the frame data for detecting transmission errors. The integrity of the audio data is further insured by storing an MD5 signature of the original unencoded audio data in the file header, which can be compared against later during decoding or testing.
* '''Fast:''' FLAC is asymmetric in favor of decode speed. Decoding requires only integer arithmetic, and is much less compute-intensive than for most perceptual codecs. Real-time decode performance is easily achievable on even modest hardware.
* '''Hardware support:''' Because of FLAC's free reference implementation, low decoding complexity and popularity, FLAC has relatively widespread hardware support compared to other lossless formats.
* '''Streamable:''' Each FLAC frame contains enough data to decode that frame. FLAC does not even rely on previous or following frames. FLAC uses sync codes and CRCs (similar to MPEG and other formats), which, along with framing, allow decoders to pick up in the middle of a stream with a minimum of delay.
* '''Seekable:''' FLAC supports fast sample-accurate seeking. Not only is this useful for playback, it makes FLAC files suitable for use in editing applications.
* '''Flexible metadata:''' New metadata blocks can be defined and implemented in future versions of FLAC without breaking older streams or decoders. Currently there are metadata types for tags, cue sheets, and seek tables. Applications can write their own APPLICATION metadata once they register an ID.
* '''Suitable for archiving:''' FLAC is an open format, and there is no generation loss if you need to convert your data to another format in the future. In addition to the frame CRCs and MD5 signature, FLAC has a verify option that decodes the encoded stream in parallel with the encoding process and compares the result to the original, aborting with an error if there is a mismatch.
* '''Convenient CD archiving:''' FLAC has a ''cue sheet'' metadata block for storing a CD table of contents and all track and index points. For instance, you can rip a CD to a single file, then import the CD's extracted cue sheet while encoding to yield a single file representation of the entire CD. If your original CD is damaged, the cue sheet can be exported later in order to burn an exact copy.
* '''Error resistant:''' Because of FLAC's framing, stream errors limit the damage to the frame in which the error occurred, typically a small fraction of a second worth of data. Contrast this with some other lossless codecs, in which a single error destroys the remainder of the stream.

== Pros ==
* Portable to many systems
* Open source and freely licensed
* Hardware support (PhatBox, Kenwood MusicKeg, Rio Karma, etc. See below)
* Streaming support
* Extremely fast decoding
* Supports multichannel and high resolution streams
* Supports [[ReplayGain]]
* Supports cue-sheet (with some limitations)
* Gaining wide use as successor to [[Shorten]]

== Cons ==
* Compresses less efficiently than other popular modern compressors ([[Monkey's Audio]], [[OptimFROG]])
* Higher compression modes slow, for little gain over the default setting.

== Hardware and software that support FLAC ==
For a more comprehensive list see the [http://xiph.org/flac/links.html FLAC links page].

=== Hardware ===
==== Car stereo ====
* Kenwood [http://www.kenwood.com/cs/ce/audiofile/index.php?model=KMM KMM series]
* Pioneer [http://www.pioneer.eu/eur/products/25/121/61/overview.html Car Stereo] (search FLAC)
* JVC [http://mobile.jvc.com/product.jsp?pathId=139 KD-X "Digital Media Receivers" series] (almost all)
* Soundstream [http://soundstream.com/store/car-video/source-units.html Source Units]
* Tesla Model S
* Citroën DS5

==== Home stereo ====
* Olive's [http://www.olive.us/ Symphony] wireless digital music center
* [http://www.numark.com/ Numark]'s DJ equipment (HDX and CDX turntables, HDMIX mixer)
* [http://www.sonos.com/ Sonos Digital Music System]
* Slim Devices' [http://www.slimdevices.com/pi_squeezebox.html Squeezebox] networked audio players

==== Portable ====
* [[Apple iPod]] with [[Rockbox]] firmware
* [[iAudio M3]], M5 and X5
* [[iRiver]] iHP-120/iHP-140 with [[Rockbox]] firmware
* [[Iwod G10]]
* [[Rio Karma]]
* [http://en.wikipedia.org/wiki/SanDisk_Sansa SanDisk Sansa]
* TrekStor's [http://www.trekstor.de/en/products/detail_mp3.php?pid=66 Vibez]
* Devices running Android 3.1+
* [[Pono|Pono Player]]

=== Software ===
==== Players ====

'''Windows'''
* [[foobar2000]]
* [[MediaMonkey]]
* [[Winamp]]
*[http://mplayerwin.sourceforge.net/ MPlayer] Console player
* [http://www.cyberlink.com/products/powerdvd-ultra/features_en_US.html?&r=1 PowerDVD]
* [http://www.videolan.org/ VLC]
* [http://www.un4seen.com/ XMPlay]

'''Mac'''
* [http://coppertino.com/ VOX]
* [http://cogx.org/ Cog]
* [http://www.videolan.org/ VLC]

'''Linux'''
* [http://www.clementine-player.org/ Clementine]
* [http://www.mplayerhq.hu/ MPlayer]
* [http://www.mythtv.org/ MythTV]
* [http://www.videolan.org/ VLC]
* [[XMMS]]

==== Frontends (Windows) ====
* FLAC frontend - [http://sourceforge.net/projects/flacfrontend/ download] / [http://wiki.hydrogenaud.io/index.php?title=Download_page discussion] (ktf)
* <s> Custom [http://members.home.nl/w.speek/flac.htm Windows Frontend] (by Speek) </s>

==== Frontends (Mac) ====
* [http://www.sbooth.org/Max/ Max]

==== Converters ====
* [http://www.dbpoweramp.com/ dBpowerAMP] Music Converter / Audio Player / CD Writer
* [http://www.mediamonkey.com/ MediaMonkey] Music Manager / Audio Player / CD Writer
* [http://www.freac.org/ fre:ac] Music Converter / CD Writer/Ripper

==== Editors ====
*[http://audacity.sourceforge.net/ Audacity]
* [[Adobe Audition]]
* [http://www.goldwave.com/ GoldWave]

==== CD writers/rippers ====
* [http://www.nero.com/eng/ Nero]
* [http://arson.sourceforge.net/ Arson]
* [http://www.burrrn.net Burrrn] Audio CD burner
* [[Exact Audio Copy]] CD Ripper
* [http://cdexos.sourceforge.net CDex] CD ripper
* [http://www.cdwave.com/ CD Wave]
* [http://cdburnerxp.se/ CDBurnerXP] CD writer
* [http://www.mediamonkey.com/ MediaMonkey] - CD ripper/writer

==== Taggers ====
* [http://www.mp3tag.de/en/index.html Mp3tag] - Universal Tag Editor
* [http://www.jtclipper.eu/thegodfather/ The GodFather] - Tagger / Music manager
* [http://sbooth.org/Tag/ Tag] - for Mac OS X 10.4 (Tiger)

* [http://www.synthetic-soul.co.uk/tag/ Case's Tag] - Command line tagger
* [https://xiph.org/flac/documentation_tools_metaflac.html metaflac] - for general metadata (including Vorbis comments) maintenance
* [[MediaMonkey]] - Tagger / Music manager (Including multiple and linked album art support)
* [http://www.xdlab.ru/en/ TagScanner] - "The Ultimate Tag Editor"

==== Other tools ====
* [http://www.bunkus.org/videotools/mkvtoolnix/ mkvtoolnix] - tool to multiplex FLAC streams inside the Matroska container
* [https://xiph.org/flac/documentation_tools_metaflac.html metaflac] - for general metadata (including Vorbis comments) maintenance, also to calculate [[ReplayGain]] values for FLAC files lacking such

for a more comprehensive list use the '''External Links''' bottom of this page to visit flac's download and link page.

== Frequently asked questions ==
''Question:'' Does the compression level affect decompression speed?

''Short Answer'': No.

''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.

''Question:'' What is the best compression level for encoding my music?

''Short Answer'': The default setting, 5.

''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.

== See also ==
* [[Lossless]]
* [[Lossless comparison]]

== External links ==
* [https://xiph.org/flac/ FLAC Homepage] | [https://xiph.org/flac/format.html format description] | [https://xiph.org/flac/documentation.html documentation] | [https://xiph.org/flac/faq.html FAQ] | [https://www.xiph.org/flac/download.html download]
* [http://www.hydrogenaud.io/forums/index.php?showforum=67 FLAC discussion]
* [http://www.hydrogenaud.io/forums/index.php?showtopic=107611 FLAC 1.3.1 discussion]
* [http://www.hydrogenaud.io/forums/index.php?showtopic=107913 FLAC 1.3.1 non-SSE2 build for older CPUs]
* ktf's [http://www.hydrogenaud.io/forums/index.php?showtopic=107990 Lossless codec comparison] graphs the influence of the chosen encoding level on the encoding and decoding performance of FLAC 1.3.1 and various other lossless codecs. Omion's older test, "[http://web.archive.org/web/20091108104748/http://people.ucsc.edu/~rswilson/flactest File Size vs. Decoding Speed"], covers the influence of the chosen encoding level on the decoding speed of FLAC 1.2.1.

[[Category:Lossless]]
[[Category:Encoder/Decoder]]

Hydrogenaudio Knowledgebase - User contributions [en]

Lossless

Free Lossless Audio Codec