[vorbis] questions about artifacts in low bitrate streams

[rillian at telus.net]

On Monday, April 23, 2001, at 04:24 , Peter Schüller wrote:

> How do you do that anyway? If I specify even "32" to oggenc, the average
> bitrate still ends up at 80 or something.

the bitrate setting isn't really a target bitrate, it just selects an 
appropriate set of codebooks which should more or less match the 
requested size for 44.1 kHz stereo input. Since we don't yet have 
codebooks for any other sample rates, it just picks the lowest 44.1 mode 
available.

Oggenc at least respects the input sample rate, however, so to do low 
bitrate compression, downsample your source with another utility first, 
and then compress with '-b 1' for the lowest possible setting. I've been 
able to get reasonable-sounding ~30 kbps streams from 22.050kHz mono 
input.

Of course the psychoacoustics aren't at all tuned for non-44.1 sample 
rates, so things won't sound nearly as good as they could, but it's 
something.

Hope that helps,
  -ralph

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