Vorbis - Jul 2000 - ogglame and LAME 3.85 beta

Hi there,

I have a question on ogglame, especially on its compression
quality.

I've download the binary package of ogglame from www.vorbis.com.
It works fine.  I've also tried LAME 3.85 beta that supports the
encoding and decoding of Vorbis streams.  I believe that ogglame
is a beta version of LAME.  I built LAME using libvorbis in the
CVS nightly snapshot fetched on July 19th.  I fixed a bug in
lame3.85/vorbis_interface.c to get a correct output bitstream
(the fix has been already in the CVS repository of LAME).

My question is that the file size of a Vorbis stream encoded by
ogglame is about 30% smaller than one encoded by LAME.  Where
does this difference come from?  Does ogglame have some special
optimizations built in the encoder?  I was not able to achieve
the better compression quality using LAME with any command line
options.

Any comments are appreciated.  Thanks,


-- 
KAJIYAMA, Tamito <kajiyama@grad.sccs.chukyo-u.ac.jp>

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Hi Tamito,
>My question is that the file size of a Vorbis stream encoded by
>ogglame is about 30% smaller than one encoded by LAME.  Where
>does this difference come from?  Does ogglame have some special
>optimizations built in the encoder?  I was not able to achieve
>the better compression quality using LAME with any command line
>options.
The difference you're seeing in file size is most likely due to different 
bitrates.  I remember seeing a message that the source that's currently in 
CVS is set to ~160 kbps, while the precompiled ogglame (from vorbis.com) was 
linked against an older version of the library and set at about 128 kbps.

Libvorbis right now only has one predefined mode ("bitrate"), and so 
changing command-line options for lame won't make any difference.

regards,
Andy Key
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