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  1. #1
    Registered User
    Join Date
    Mar 2003
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    5

    How to control audio recording buffer size for 6120 classic

    Hi,

    I try to record and play audio in PCM16 mode using CMMFDevSound with sampling rate of either 8 kHz or 16 kHz. The request buffer size is 4096 bytes for both recording and playing for N95 and I have no problems with these devices. For Nokia 6120 classic, however the request buffer sizes for recording and playing are different (1600 and 4096 bytes respectively). The mismatch makes it difficult or even impossible to achieve full audio duplex using this method. Does anyone encounter and have a solution for this problem?

    Thanks,
    Minh.

  2. #2
    Super Contributor
    Join Date
    Mar 2004
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    Czech Republic
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    2,037

    Re: How to control audio recording buffer size for 6120 classic

    Hi,

    where is the problem, why different buffer sizes makes full duplex impossible?

    BR
    STeN

  3. #3
    Registered User
    Join Date
    Mar 2003
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    5

    Re: How to control audio recording buffer size for 6120 classic

    My application plays back the recorded samples. If the buffer sizes are equal, I just pass all the recorded samples to the CMMFDevSound play stream and there is no problem. Since the play buffer is (much) larger than the record buffer, the CMMFDevSound play stream has to wait (too long) for the record stream to accumulate enough bytes before it can play. This severely affects the quality of the audio play stream, and in fact it does not produce audible sound at all.

    Minh.

  4. #4
    Registered User
    Join Date
    Dec 2006
    Posts
    2,280

    Re: How to control audio recording buffer size for 6120 classic

    Hi,

    Assuming you are both recording and playing back at the same sample rate then speed of buffer fill/empty shouldn't be a problem. What you would need to do though is keep buffers queued up at the beginning until you have enough to fill a playback buffer. Effectively you need to implement some sort of FIFO with a very short delay before you start playback. Also make sure that you do fill the buffers.

    CMdaAudioInputStream and CMdaAudioOutputStream effectively do this for you, although you can get more control by implementing it yourself.

    Sorcery

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