[vorbis-dev] lossless ogg encoding with good compression rate

[Christian Hack]

> -----Original Message-----
> From: owner-vorbis-dev at xiph.org 
> [mailto:owner-vorbis-dev at xiph.org] On Behalf Of General purpose mail
> Sent: Thursday, 26 June 2003 10:41 AM
> To: vorbis-dev at xiph.org
> Subject: [vorbis-dev] lossless ogg encoding with good compression rate
> 
> 
> I think that there is a very simple way to encode audio files 
> with lossless compression around 35%.
> (the compression may be improved if we can lose some lsb bits 
> around 30% for 2 and 25% for 3)
> Other lossless audio encoder I've seen reach at maximum a 
> compression of 48% (*.flac, *.ape)
> 

...

> 
> Follow the description of how I've tested it:
> 1) create a wav file [A.wav]:
> 2) encode it in ogg format (my best result with high 7) [B.ogg]
> 3) decode the ogg into a wav again [C.wav] (the size will be 
> the same as A.wav)
> 4) create a file with the diff of each sample from A.wav with 
> B.wav [D.tmp] also with the  same size at least of the header.

I think you mean C.wav not B.wav

> 5) bzip2 the D.tmp [D.tmp.bz2]
> 6) keep B.ogg and D.tmp.bz2 (the size will be around 17% of 
> the original for each file)
> 

Very interesting way to do it, but if you're only getting around %35 and
FLAC is getting around %48 then why reinvent the wheel.

Perhaps I am misunderstanding your numbers. Are you talking a percentage
of original size OR percentage of original size saved. If it's the
former read on. If it's the latter ignore the rest of this message.

Have you encoded with FLAC on the source you are using? I have found the
FLAC compression estimates seem a little optimistic for a lot of my
stuff. I get more like %66 of the original size (in your terms %33
compression?)

Either way, there's probably more CPU required than simply decoding an
OGG since you have to do decode the OGG, bunzip the diff AND apply the
diff...

My 2c....

CH

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