On Tue, Jun 22, 2010 at 8:00 AM, Adrian Knoth <a...@drcomp.erfurt.thur.de>wrote:
> On Tue, Jun 22, 2010 at 06:38:45AM -0400, Gene Heskett wrote: > > > >from TFA: > > >: Implemented in a DSP chip or microprocessor, this simple compressor > > >: requires about 50 instructions per sample. However, lossless > > >: compression ratios fall between 1.3:1 and 2:1 on baseband signals. > > > > > >So a size of 75% expected and on occasion down to 50% after compression. > > >How is that compared to existing implementations? > > It was the lossless claim that got my attention, Jens. I am well aware > > that current compressors can beat that at "acceptable" quality. But an > > ogg at q7 > > Jens was never talking about lossy "compression", which I call data > reduction to avoid the ambiguity with real compression (as in ZIP). > > Lossless audio coding is nothing new, FLAC has been around for years. > Your referenced codec achives 1.3:1 to 2:1. One can compare this to some > values provided here: > > > http://web.inter.nl.net/users/hvdh/lossless/lossless.htm > > > These are all lossless codecs, and as one can see, only few manage to > come close to 2:1 (50% compression). > > However, results for predictive coding (derivation based approaches) > vary a lot depending on the input signal. As a rule of thumb, a pure > sine is easier to predict than noise, which more or less is the > mathematical equivalent of randomness (I'm sure Fons could go into > detail here, if necessary). > > > Long story short: I don't think your link contains something > extra-ordinary, just another me-too approach of well-known techniques. > It might save you a few bits, but you'll have to measure it. Fire up > octave, load the matlab script, encode a wave file and compare it to > FLAC. > > If your referenced algorithm gives striking results, then convince > everybody to forget about FLAC and use this new algo instead. Let me > predict that neither the first nor the latter will happen. ;) > > > That's more or less the end of the story. Any further discussion would > only make sense with measured results at hand. > > > HTH > > -- > mail: a...@thur.de http://adi.thur.de PGP/GPG: key via keyserver > _______________________________________________ > Linux-audio-dev mailing list > Linux-audio-dev@lists.linuxaudio.org > http://lists.linuxaudio.org/listinfo/linux-audio-dev > I've tested flac -8 and the given matlab script on a wav file. The matlab script reports a compression ratio of 7.9908, and flac reports a compression ratio of 0.521, obviously, they measure in inverse ways, but 7.99 still seems excessively high. Jeremy
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