[vorbis] Ogg Voxpop

[Gregory Maxwell]

On Mon, Feb 12, 2001 at 07:50:25PM -0500, Keith Wright wrote:
[snip]
> My current thought is to filter the input down to a bandwidth
> of 7KHz or 4KHz (traditional values for high and low quality
> speech), decimate the samples so that the sound is sampled
> at, say, 44/3=14.6KHz or 44/5=8.8KHz, then run it through
> the standard Vorbis encoder.  Vorbis then sees an ordinary
> 20KHz bandwidth stream that sounds like a tape recording
> running at 3 to 5 times normal speed and encodes it as
> usual.
[snip]
> the sample sequence.  We don't need to do that again, so
> assume the filtering and decimation is done properly,
> is there any reason this scheme could not work?  Are
> there hooks in the Vorbis stream format to tell the decoder
> that this as been done so that it will know to play back
> slower than normal?  Do I have to write all this myself,
> or is it already in there if I just know the parameter to set?

Vorbis can happily take in a 8.8KHz (or just about any other) sampling rate
file and act accordingly. If you like to vorbis (make it think it's
chipmunks) you will get HORRIBLE results because the psycoacustic masking is
highly frequency dependant and vorbis will get the masking all wrong.

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