RK Audio: Difference between revisions

Latest revision as of 05:58, 15 August 2023

RK Audio (RKAU) is a legacy lossless (and lossy) audio codec for the Windows platform. It was developed by Malcolm Taylor together with RK (a general purpose data compressor) and RKim (a lossless image compressor).
Development apparently ceased around year 2000; the author offered it for download until circa 2005 at his new company MSoftware, which then for a while revived the compression suite (including an audio compressor) as the WinRK archiver, now also discontinued.

Testing by ReallyRareWares and Squeezechart indicated excellent compression level by year 2000 standards, at the cost of high CPU usage. Features were few.

ffmpeg has a decoder obtained by reverse engineering the lossless RKAU codec. Apparently it also decodes one of the two known lossy profiles (the "simple" lossless profile), but the user should be cautioned that the other lossy profile ("VRQ") is decoded wrong and produces noise without giving any warning (as of ffmpeg 6.0).

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-'''RK Audio''' ('''RKAU''') is a [[lossless]] (and [[lossy]]) audio compressor. It was developed by Malcolm Taylor together with RK (a general purpose data compressor) and RKim (a lossless image compressor).
+'''RK Audio''' ('''RKAU''') is a legacy [[lossless]] (and [[lossy]]) audio [[codec]] for the Windows platform. It was developed by Malcolm Taylor together with RK (a general purpose data compressor) and RKim (a lossless image compressor). <br/>
+Development apparently ceased around year 2000; the author offered it for download until circa 2005 at his new company MSoftware, which then for a while revived the compression suite ([http://www.squeezechart.com/audio.html including an audio compressor]) as the WinRK archiver, now also discontinued.
-At some point, some years ago, it featured the best compression levels among the lossless audio encoders. But then development halted and competitors like [[Monkey's Audio]], [[OptimFROG]] and [[Lossless Audio]] caught on.
+Testing by ReallyRareWares and Squeezechart indicated excellent compression level by year 2000 standards, at the cost of high CPU usage.  Features were few.
-It was closed source. Added to that, it was very slow on decoding and had few features. So, it never became a really popular format.
+ffmpeg has a decoder obtained by reverse engineering the lossless RKAU codec. Apparently it also decodes one of the two known lossy profiles (the "simple" lossless profile), but the user should be cautioned that the other lossy profile ("VRQ") is decoded wrong and produces noise without giving any warning (as of ffmpeg 6.0).
-Recently, RKsoft was revived by Malcolm Taylor, now with the name MSoftware, so there is hope RKAU development will start again.
+=== Further reading ===
+* [https://wiki.multimedia.cx/index.php/RK_Audio RK Audio at MultimediaWiki]
+* [https://www.rarewares.org/rrw/rkau.php RKAU at ReallyRareWares]
+* [https://hydrogenaud.io/index.php/topic,123654 HA forum post announcing ffmpeg support]
+{{navbox audio codecs}}
 [[Category:Codecs]]


Audio codecs: type/usage	for end-users to encode	on physical media etc.	legacy formats
Lossless	(Uncompr. LPCM) • ALAC • FLAC • Monkey's Audio • MPEG-4 ALS • OptimFROG • TAK • TTA • WavPack	MLP/Dolby TrueHD	La • LPAC/LTAC • RealAudio Lossless • RK Audio • Shorten • WMA Lossless • (others)
Lossy	(ADPCM formats) • AAC • AC-3 • MP2 • MP3 • Musepack • Opus • Vorbis	AC-3 • DTS • (Bluetooth codecs)	ATRAC • QDesign • Real Audio • RK Audio (lossy modes) • Speex • VQF • WMA
Hybrid lossless&lossy	OptimFROG DualStream • WavPack	DTS-HD MA • MPEG-4 SLS	ATRAC Advanced Lossless • mp3HD