[Speex-dev] Regression in wideband encoding quality between b1 and rc1

Blaise Potard bpotard at gmail.com
Tue Dec 15 07:37:08 PST 2009


To start with, thanks a lot for making such a great voice codec available!

Having recently upgrading to speex rc1, It occurred to us that there
seems to have been a regression in the quality of encoding since
version beta1.

We are compressing some 22khz wave files in wb mode with maximum
quality / complexity in VBR, and the result was really great with
speex beta1. With rc1 (or beta3), there is a clear degradation for
fricatives, which gives a very audible (and annoying) feeling of a
muffled voice.

This problem does not seem to affect CBR encoding, only VBR. It does
not appear to affect 16k files as much either.

Hope that will help you improve speex again!

P.S.: Is there any plan to make uwb mode really usable? At the moment,
compressed 32k wave files sound worse than 16k in maximum quality.
Would it be a lot of work to make the bitrate of the upper band to
depend on the quality setting, instead of being hard-coded at 1.8kb?

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