Speex dev - May 2008 - preprocesssor questions

Hi,

I have been looking at the speex library and I like it a lot. Good job! I
have a couple of questions regarding the preprocessor:

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?

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.

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?

Thanks,
-Florian
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Florian a ?crit :
> 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?
Yes.
> 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.

	Jean-Marc