Automatic Gain Control (AGC)/Voice Activity Detection (VAD)

[john440]

Hello,

Sorry had posted in a different forum. Hopefully this is the right forum to address this issue:


We are developing an application which takes audio from the microphone and does some analysis. We found during the analysis, that AGC and VAD are implemented on the microphone subsystem. We would like to know if

1. Are there any other post processing done on the audio(PCM) before it is delivered to the application?
2. Is it possible for the application to disable the AGC and VAD post processing? We know that this is disabled if we do a recording in AAC format.
3. Any idea on the characteristics (alogorithm) used for AGC and VAD

Thanks in advance,
John J Chooracken

[skumar_rao]

refer to your other post. http://discussion.forum.nokia.com/fo...d.php?t=162234

[sergiosmail]

Hi John.
Do you have some success disabling AGC?
Is possible to do it? Can you share some information about this function?

Thanks,
Sergio

[john440]

Hi Sergio,

There is an API called SetGain/GetMaxGain in CMdaAudioInputStream, but in S60 phones the range is between 1-1, so not very useful using this API.

But you can use CVoIPAudioUplinkStream which allows you to dynamically control the audio gain and other codec properties.

Regards,
John

[sergiosmail]

thank you john. I'll try