[pjsip] about audio question!

Nanang Izzuddin nanang at pjsip.org
Thu Apr 17 00:44:25 EDT 2008


Hi Tanger,

Some sound cards do have clock drift, recording and playing do not
have exact same clock rate, (and this usually will hurt the AEC, but
not in your case?). sndtest sample app can be used to check drift
level of your sound card.

However it is a bit strange on your case, since usually AEC will work
well when there is no clock drift, and AEC becomes inefficient/not
working when there is drift. But, your experience is on the contrary
of those usual behavior.

So, if you are sure that the AEC works well (echo is canceled) in
ptime==10, where the drift occurred, then just use this setting :)

You may want to try opening the sound card in clock rate 48kHz which
usually produce less drift.


Regards,
nanang


On 17/04/2008, cat tanger <tanger_wendy at yahoo.com.cn> wrote:
>
>
>
> hi,all,
> please help me!
> I use pjproject-0.8.0,
>
> when i set  audio_frame_ptime = 20,aec = 1,  then  PaRecorderCallback and
> PaPlayerCallback function run exactly, but aec can't work well, do not
> cancell echo .
>
> when i set  audio_frame_ptime = 10,aec = 1,  then  aec can work well . but
> the PaRecorderCallback and PaPlayerCallback function do not work well,
> portaudio callback the PaRecorderCallback times far more callback
> PaPlayerCallback times, it result the aec continue reset. i find underflow
> in the PaPlayerCallback.
>
> pls help me!
> thanks!
>
>
> test code:
>
> static int capcounts = 0,playcounts = 0;
>
> static int PaRecorderCallback(const void *input,
>          void *output,
>          unsigned long frameCount,
>          const PaStreamCallbackTimeInfo* timeInfo,
>          PaStreamCallbackFlags statusFlags,
>          void *userData )
> {
>     .....
>  capcounts ++;
>  if (capcounts%500 == 0)
>  {
>   PJ_LOG(5,(THIS_FILE, "Recorder thread capcounts = %d,playcounts =
> %d",capcounts,playcounts));
>  }
>    ....
>     return paAbort;
> }
>
> static int PaPlayerCallback( const void *input,
>         void *output,
>         unsigned long frameCount,
>         const PaStreamCallbackTimeInfo* timeInfo,
>         PaStreamCallbackFlags statusFlags,
>         void *userData )
> {
>    ....
>   playcounts ++;
>   if (playcounts%500 == 0)
>   {
>    PJ_LOG(5,(THIS_FILE, "Player thread capcounts = %d,playcounts = %
> d",capcounts,playcounts));
>   }
>    ....
>   return paAbort;
> }
>
>
> print :
>  11:11:06.703    aec00EA2B70 AEC reset, delay=-65, prefetch=10
>  11:11:06.921      pasound.c Recorder thread capcounts = 500,playcounts =
> 434
>  11:11:07.062    aec00EA2B70 AEC reset, delay=-66, prefetch=10
>  11:11:07.609      pasound.c Player thread capcounts = 568,playcounts = 500
>  11:11:07.734    aec00EA2B70 AEC reset, delay=-69, prefetch=10
>  11:11:11.921      pasound.c Recorder thread capcounts = 1000,playcounts =
> 903
>  11:11:11.921    aec00EA2B70 AEC reset, delay=-89, prefetch=10
>  11:11:12.828      pasound.c Player thread capcounts = 1089,playcounts =
> 1000
>  11:11:13.140    aec00EA2B70 AEC reset, delay=-90, prefetch=10
>  11:11:16.906      pasound.c Recorder thread capcounts = 1500,playcounts =
> 1376
>  11:11:17.203    aec00EA2B70 AEC reset, delay=-123, prefetch=10 1
>  11:11:18.390      pasound.c Player thread capcounts = 1646,playcounts =
> 1500
>  11:11:18.390    aec00EA2B70 AEC reset, delay=-140, prefetch=10
>  11:11:21.921      pasound.c Recorder thread capcounts = 2000,playcounts =
> 1817
>  11:11:23.171    aec00EA2B70 AEC reset, delay=-183, prefetch=10
>  11:11:23.828      pasound.c Player thread capcounts = 2191,playcounts =
> 2000
>  11:11:24.234    aec00EA2B70 AEC reset, delay=-192, prefetch=10
>  11:11:26.921      pasound.c Recorder thread capcounts = 2500,playcounts =
> 2253
>  11:11:26.937    aec00EA2B70 AEC reset, delay=-239, prefetch=10 1
>  11:11:29.703      pasound.c Player thread capcounts = 2779,playcounts =
> 2500
>  11:11:29.937    aec00EA2B70 AEC reset, delay=-278, prefetch=10
>  11:11:31.906      pasound.c Recorder thread capcounts = 3000,playcounts =
> 2681
>  11:11:32.140    aec00EA2B70 AEC reset, delay=-311, prefetch=10
>
>
>
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