On Wed, 13 Oct 1999, Gabriel Bouvigne wrote:
> The voice mode is made using 3 tricks:
> *using only long blocks
> *limiting bitrate when vbr
> *using a band-pass filter
For a more sophicated hack:
Panned stereo mode!
For each frame you examine a spectrally weighed (ignore low freqs) energy
ratio of left/right to pick the stereo panning at two points in time
(middle, and right) then interpoate from old_left to middle then right,
enforcing a maximum rate of change.
Then mix to mono, encode as mid, and the position as side, you only have
to encode lower scalfactors because it should consist of low freqs only
(because of your slow interpolation). I suppose you could shape your side
wav to MDCT well too..
Am I missing something?
I'd think that this would allow you to get mono quality at about the same
bitrate, but still preserve panning which would be help at differentiating
between people speaking.
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