Speex dev - Sep 2005 - Adjustable parameters for VAD in preprocessor

*Sigh* Some day I'll learn to set the right sender address when posting to 
membership-restricted mailing addresses. Was wondering why this hadn't 
arrived. Reposted message as follows:



Hi,

Would a patch to change the constants on line 454 - 462 in the preprocessor 
into variables be of general interest? At the moment, whether or not 
"is_speech" is 1 is hardcoded to be (speec_prob > .35 or >.1
within last 20
frames or it's been less than 20 frames without).. I'd like to turn
those 4
constants into speex_preprocess_ctl tunable variables, most likely through 
SPEEX_PREPROCESS_GET_VAD_PARAMETERS / SET_VAD_PARAMETERS with ptr being a 
pointer to

typedef struct {
   float trigger_level;
   float keep_level;
   int keep_window;
   int tail_length;
} SpeexPreprocessVadParameters;

I'm a bit unsure if keep_window (used with prob > .1) should be the same
as
tail_length. At the moment, I have an external counter in my program that keeps 
track of how many frames it's been since the vad returned 1, and if it's
less
than a user-set ammount, treat it as if it's still voice. This works well
for
users that have slightly long pauses between sentences or words.

Hi,

If you can come up with a clean (non-intrusive) patch, I'm willing to
apply it. Ideally, it should go through int parameters to
speex_preprocess_ctl(). I think someone sent a similar patch to the list
a while ago, but I didn't have time to do the little cleanup it needed.

	Jean-Marc
> Hi,
> 
> Would a patch to change the constants on line 454 - 462 in the preprocessor
> into variables be of general interest? At the moment, whether or not 
> "is_speech" is 1 is hardcoded to be (speec_prob > .35 or
>.1 within last 20
> frames or it's been less than 20 frames without).. I'd like to turn
those 4
> constants into speex_preprocess_ctl tunable variables, most likely through 
> SPEEX_PREPROCESS_GET_VAD_PARAMETERS / SET_VAD_PARAMETERS with ptr being a 
> pointer to
> 
> typedef struct {
>    float trigger_level;
>    float keep_level;
>    int keep_window;
>    int tail_length;
> } SpeexPreprocessVadParameters;
> 
> I'm a bit unsure if keep_window (used with prob > .1) should be the
same as
> tail_length. At the moment, I have an external counter in my program that
keeps
> track of how many frames it's been since the vad returned 1, and if
it's less
> than a user-set ammount, treat it as if it's still voice. This works
well for
> users that have slightly long pauses between sentences or words.
> _______________________________________________
> Speex-dev mailing list
> Speex-dev@xiph.org
> http://lists.xiph.org/mailman/listinfo/speex-dev
> 
-- 
Jean-Marc Valin <Jean-Marc.Valin@USherbrooke.ca>
Universit? de Sherbrooke
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