[vorbis-dev] Major quality decrease in RC3 compared to RC2
jack at xiph.org
Sun Jan 6 10:04:35 PST 2002
> But - sorry for objecting your work - one thing is strange: the so-generated
> ogg file sounds much better than the one I did before (using -b 128).
> Nevertheless, the new one is a bit smaller in size. Or to put it the other
> way round: "-b 128" gives you less quality at bigger filesizes than "-q 3.5".
> That way I would say the bitrate-management in RC2 was more useable than the
> new one. (Sorry.)
This is perfectly normal. -b 128 turns on bitrate management, as you'll
see a little note pop up in oggenc. "Encoding with managed bitrates."
These are made to restrict the VBR vorbis engine to produce files that
are better suited for environments like streaming.
-M and -m are also bitrate management flags, and specific maximum and
minimum bitrates respectively.
This is the first cut of bitrate management, so the quality will
improve. At the same time, it's not expected that this be heavily used,
since it's a specialized feature so that one can make guaruntees about
bandwidth or hardware performance, etc.
-q uses the unconstrained engine tuned for certain 'areas'. -q0 will
produce something aroudn 64kbps, -q4 around 128, etc. But -q will
always sound better than -b or -M.
Hope this explains it well enough.
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