[vorbis] Is there an oggenc low bit rate HOWTO?

[Moritz Grimm]

Mark Hetherington wrote:
> oggenc -M 16 --downmix in.wav
> will give you a mono (downmixed from stereo) ogg with a maximum bitrate of
> 16kbps...

This will give you something with a nominal bitrate of 112 or 128 kbps
and a maximum of 16kbps. Even IF that would work, it would sound
horrible. You should set a bitrate with -b to keep the encoder from
using the defaults.

To get below 48kbps stereo, you might want to test resampling
('--resample 22050' for example), and of course --downmix for mono,
combined with low -q values for nice quality.

To use bitrate management properly, I suggest you look at the nominal
bitrate of your testfiles from the last paragraph, e.g. check out where
-q 0 actually is, nominally, when working on a 11025 kHz mono sample. I
could slap myself for deleting my own testfiles, otherwise I could help
some more, here. :P

Anyways, in the end you have those nominal bitrates, and the good thing
about them is to know what Vorbis would have chosen. You can take these
values and create reasonably nice --managed -b <something> files that
way. After doing so, you *might* find it necessary to restrict the
encoder more, e.g. with --managed -b 16 -M 20. (Makes sense if you may
not allow the tiniest bitrate peaks... can't really recommend it,
though, for the sake of quality.)

<p><p>Moritz

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