[Speex-dev] preprocesssor questions

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Sat May 17 01:58:26 PDT 2008

Florian a écrit :
> 1) I looked at the source code. Even though I am an experienced
> programmer it looks like Chinese to me ;-) What would I have to do to
> modify / tweak the audio processing code for my needs? Are there
> documents describing the algorithms applied for AGC, NS and VAD or does
> one have to understand the source code? How do people help you modifying
> the library  - do they magically understand the code?

I think normally it helps when you actually understand what you're
changing. The other day, I was playing around with the Linux kernel
source code and removed the scheduler. For some reason, the new kernel
failed to boot. Strange...

> 2) I run the preprocessor it seems to take the same amount of time to
> run VAD+NS+AGC as if I only run VAD. Is it possible to restructure the
> code in a way that saves cpu cycles if I only run the VAD?


> 3) Or more specifically is it possible to only run the VAD and only if
> the VAD returns speech do the real precessing (AGC, NS). Basically save
> CPU if there is no real voice.

No, or else the AGC and NS will suck.

> 4) You are writing that people are working on improving the VAD. Again
> are there documents decribing the changes or how does one get started?

No, sorry. The little time I have to spend on this is spent on the
actual code rather than doc.


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