[Speex-dev] preprocesssor questions

[Eran Hashin]

Hi
Thank you for your work.
We are trying to use the speex SW with a C6000 TI DSP.
I am working with an HW codec that does AGC by HW inside.
Will doing the AGC before the preprocessor make a problem?
Does VAD work well in a noisy eviroment?
In SW there are some remarks on things to be fixed, can I count on SW as working or are some part still to be improved.
I also tried to understand SW but I guess I was unable to.
Where are the version will the latest patches located?
Best regards,
Eran Hashin


-----Original Message-----
From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org]On Behalf Of Jean-Marc Valin
Sent: Saturday, May 17, 2008 10:58 AM
To: florian.winterstein at gmail.com
Cc: speex-dev at xiph.org
Subject: Re: [Speex-dev] preprocesssor questions


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?

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
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