Difference between revisions of "Sac"

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{{stub}} '''Sac''' is an apparently experimental [[lossless]] audio [[codec]]. It comes with source code and a Windows 64-bit executable.  
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{{stub}} '''Sac''' can refer to (at least) one out of two lesser-known audio [[codec|codecs]], which are not aimed at end-users.
  
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Sac is arguably not an end-user codec, lacking pretty much all the features those possess (see the [[Lossless_comparison|HA Wiki's Lossless Codec Comparison]]).  Rather, it seems to be dedicated to achieving smaller file size than any other lossless codec whatever computing power it might take.  Thus, decoding might fall severely short of real-time speeds: The developer uses as benchmark [[OptimFROG]]'s max preset<ref>https://github.com/slmdev/sac</ref>, which has been measured to decode at around 4x realtime<ref>http://www.audiograaf.nl/losslesstest/Lossless%20audio%20codec%20comparison%20-%20revision%204.pdf</ref>; cursory testing indicates that Sac (v0.5.1) is order of magnitude ten times as CPU intensive.  Independent comparison measured Sac does to smaller files size on average (but not all) material.<ref>http://www.squeezechart.com/audio.html</ref>
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'''Sac''' &ndash; also referred to as ''State-of-the-Art lossless compression'' &ndash; by Sebastian Lehmann<ref>https://github.com/slmdev/sac  Sebastian Lehmann's Sac at github</ref>: a [[lossless]] (on given architecture<ref>https://github.com/slmdev/sac/issues/7  Github issue: losslessness not preserved across CPU architectures</ref>) codec, described by the author as ''a lossless audio compression intended as a research project to find the limits on compression ratio''<ref>https://encode.su/threads/1137-Sac-(State-of-the-Art)-Lossless-Audio-Compression  Lehmann's 2010 post at encode.su, updated</ref>. It comes with source code and a Windows 64-bit executable. <br/>
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Being a an experimental research project, it lacks pretty much all the features of an end-user codec (including playback support, see also the [[Lossless_comparison|HA Wiki's Lossless Codec Comparison]]).  Rather, Sac is dedicated to achieving smaller file size than any other lossless codec, at great expenses in computing power: Decoding might fall severely short of real-time speeds. The developer uses as benchmark [[OptimFROG]]'s max preset, which in the 2023 edition of Martin van Beurden's lossless test<ref>http://www.audiograaf.nl/losslesstest/Lossless%20audio%20codec%20comparison%20-%20revision%206%20-%20cdda.html Martijn van Beurden's 2023 lossless comparison study</ref> was measured to decode at 10x realtime speed on current hardware; cursory testing indicates that Sac (v0.5.1) is order of magnitude ten times as CPU intensive.  Independent comparison measured Sac does to smaller files size on average (but not all) material.<ref>http://www.squeezechart.com/audio.html Squeezechart's comparison of (lossless) compressors</ref>
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'''Sac''' &ndash;  ''Simple Audio Compression'' &ndash; by Marcus Geelnard<ref>https://www.bitsnbites.eu/hiqh-quality-dpcm-attempts  Marcus Geelnard's 2014 blog post</ref>: a simple codec for 4-bit and 8-bit DDPCM. Released as a library.<ref>https://gitlab.com/mbitsnbites/libsac  Marcus Geelnard's Sac at gitlab</ref>
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'''References:'''
  
 
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[[Category:Codecs]]
 
[[Category:Codecs]]

Latest revision as of 11:47, 22 March 2024

This article is a stub. You can help the Hydrogenaudio Knowledgebase by expanding it.

Sac can refer to (at least) one out of two lesser-known audio codecs, which are not aimed at end-users.

Sac – also referred to as State-of-the-Art lossless compression – by Sebastian Lehmann[1]: a lossless (on given architecture[2]) codec, described by the author as a lossless audio compression intended as a research project to find the limits on compression ratio[3]. It comes with source code and a Windows 64-bit executable.
Being a an experimental research project, it lacks pretty much all the features of an end-user codec (including playback support, see also the HA Wiki's Lossless Codec Comparison). Rather, Sac is dedicated to achieving smaller file size than any other lossless codec, at great expenses in computing power: Decoding might fall severely short of real-time speeds. The developer uses as benchmark OptimFROG's max preset, which in the 2023 edition of Martin van Beurden's lossless test[4] was measured to decode at 10x realtime speed on current hardware; cursory testing indicates that Sac (v0.5.1) is order of magnitude ten times as CPU intensive. Independent comparison measured Sac does to smaller files size on average (but not all) material.[5]

Sac – Simple Audio Compression – by Marcus Geelnard[6]: a simple codec for 4-bit and 8-bit DDPCM. Released as a library.[7]

References:

  1. ↑ https://github.com/slmdev/sac Sebastian Lehmann's Sac at github
  2. ↑ https://github.com/slmdev/sac/issues/7 Github issue: losslessness not preserved across CPU architectures
  3. ↑ https://encode.su/threads/1137-Sac-(State-of-the-Art)-Lossless-Audio-Compression Lehmann's 2010 post at encode.su, updated
  4. ↑ http://www.audiograaf.nl/losslesstest/Lossless%20audio%20codec%20comparison%20-%20revision%206%20-%20cdda.html Martijn van Beurden's 2023 lossless comparison study
  5. ↑ http://www.squeezechart.com/audio.html Squeezechart's comparison of (lossless) compressors
  6. ↑ https://www.bitsnbites.eu/hiqh-quality-dpcm-attempts Marcus Geelnard's 2014 blog post
  7. ↑ https://gitlab.com/mbitsnbites/libsac Marcus Geelnard's Sac at gitlab
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