[Speex-dev] ABR troubles

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Fri Dec 16 01:26:48 PST 2005

> .. Unfortunately, and a bit unexpectedly, the same is true for ABR. If you 
> have a loooong period of silence in the beginning, st->vbr_quality will 
> slowly increase. If you then have lots of talking, st->vbr_quality 
> decreases very very slowly as st->abr_count is now very high. The end 
> result is that the target bitrate is exceeded quite drastically over short 
> time periods. 

Well, that's why it's called *average* bit-rate ;-) The way it's
implemented (IIRC), I try to meet the average over the *complete* file
(or communication).

> Is there a way to make VBR or ABR give a guarantee of a maximum bandwidth 
> they will not exceed? Ideally, I'd like something like:

It wouldn't be too hard (already thought of that), but it's a bit far on
the TODO list. Patches are welcome.


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