On 04/12/2011 2:27 PM, Ronald S. Bultje wrote:
They're made up. The codec allows setting custom qmats in the frame
header. A good encoder will do some sort of rate distortion
optimization to find the best quantizers for each coefficient index in
the 8x8 square that gives best quality for the requested compression
(or the other way around).
This one just hardcodes 4 profiles with fixed quantizer tables, which
is a little bit lame. Reminds me of Mike's VP8 encoder [1][2].
Ronald
But what I`m wondering, since these profiles are from Apple IIRC,
is if apple always uses these specific ones when its encoder uses
these profiles. If that was the case, that would be a decent reason
to keep them.
Perhaps someone can shed some light on this.
- Derek
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