[vorbis] oggenc and low bit rates

[Michael Smith]

At 12:21 AM 2/3/01 -0800, you wrote:
>
>
>how does oggenc/vorbis handle low bitrates, it seems the lowest that it
>can go is 60000 per channel, this translates to info_AA , (the comments
>in the code seem to indicate all modes to be cd quality stereo)
>
>is it possible to go lower, or is it dependant on the input khz of
>the wav file, ie a 44khz gives 120000/2, and a 22 gives 70000/2 ( this is
>what oggenc seems to be saying)
>
>i'd like to  encode some very low bitrate samples, how would i go about it?
>
>8000 per channel would be ideal.
>

You're right, roughly. mode_AA comes out at around 50 kbps/channel for most
stuff, at 44.1kHz. 

Without encoder modifications (things that will come in the future, but
there are higher priorities now), you won't be able to get down to 8kbps
with decent quality, most likely.

Lower bitrates at the same sample rate are possible, but not our focus at
the moment. In the future, it'd be reasonable to expect something as low as
64 kbps (stereo) with reasonable quality, at 44.1kHz, I think.

Until then, resample. You should be able to get down to 10-15 kbps/channel
at a sufficiently low sample rate without any changes to the encoder,
though preecho will be pretty horrible then.

Michael

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