flac dev - Sep 2004 - vorbis+flac compression

It seems, that oggenc-ing audiofile, and then flac-ing diffrences
between original file and vorbis compressed file gives a little better
compression than simply flac-ing. I've tested it on one file only:

file.wav			55829468 bytes
	flac -8	file.wav
file.flac			37924329 bytes (0.6793 of original)
	oggenc file.wav
file.ogg			 4784799 bytes
	oggdec -o ogg.wav file.ogg
	sox tmp.wav ogg-.wav vol -1.0
	soxmix file.wav ogg-.wav rests.wav
	flax -8 rests.wav
rests.flac			31353872 bytes
file.ogg+rests.flac		36138671 bytes (0.6473 of original)

Its time consuming, and decoding is harder than for flac, but both
formats are streamable. And what a jump in compression ratio...

Pozdrawiam
Slimak (na kraw?dzi)

On Mon, Jan 19, 2004 at 12:15:01AM +0100, Jan Gorski
wrote:
> It seems, that oggenc-ing audiofile, and then flac-ing diffrences
> between original file and vorbis compressed file gives a little better
> compression than simply flac-ing. I've tested it on one file only:
> 
> file.wav			55829468 bytes
> 	flac -8	file.wav
> file.flac			37924329 bytes (0.6793 of original)
> 	oggenc file.wav
> file.ogg			 4784799 bytes
> 	oggdec -o ogg.wav file.ogg
> 	sox tmp.wav ogg-.wav vol -1.0
> 	soxmix file.wav ogg-.wav rests.wav
> 	flax -8 rests.wav
> rests.flac			31353872 bytes
> file.ogg+rests.flac		36138671 bytes (0.6473 of original)
Looks cool, but there is a problem in your procedure. soxmix does
something else than just adding up the signals, therefore it is not
possible to restore the original file.

If you try a different approach (preferably lossless), you will see
that vorbis+flac size is bigger than original flac file.

-- 
Miroslav Lichvar