Audio Proxy Server FAQ

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SetDecoderMode fails

I tried many different things but didn't manage to get SetDecoderMode to work with AMR in my application. I noticed that the sample project attached to APS 2.41 did only check result of SetEncoderMode so I've added one more for SetDecoderMode and ... it turns out that it fails as well.. The error is -5 (KErrNotSupported). I tried it with N80, E61i and E60. SetEncoderMode works fine..

Any ideas?

• AFAIK, "SetDecoderMode" for sure doesn't work with AMR codec. This is just because, AMR decoder takes any AMR encoded format and decodes it irrespective of the encoded bit rate. So, for AMR, if you want to change the mode(bitrate), what all you need to do is change only the encoder mode using "SetEncoderMode".

• The problem is that I get only funny noise after changing EncoderMode for input audio but leaving DecoderMode for output audio with default bitrate. If I leave both at default bitrate (5150) everything is ok.

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Created: wmseto (17 May 2007)

Last edited: hamishwillee (06 May 2013)

Q. When the G711 packets are played out, the noise is really bad. Why?

A. Try the folloing:

• Using the SetEncoderMode and SetDecoderMode functions to set mulaw.
• Check the first word of the G.711 audio buffer from the mic for the appropriate audio format. Only process those audio buffers that were "normal speech" (value of 1). Apparently some of the audio buffers contain data which is not "normal voice.

Q. Why am I getting KErrUnderflow?

A. During player initialization, make sure stat code at the call back is successful. Receiving EAPSPlayerInitComplete is not good enough. The status code at the call back needs to be checked. When sending data to the write queue when the player has not been successfully stated, KErrUnderFlow is returned.

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