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  1. #1
    Registered User
    Join Date
    Oct 2007

    Playback latency

    Hi all, I'm planning to write an application with some stronger requirements on the timing of the playback of simple pcm wav files. To get started I wrote some JavaME code, but I'm seeing a huge (at least for my application) delay between actually starting the playback and hearing the signal. With huge I mean 100ms in this case. I have similar problems with recording - I would need to know exactly when the recording starts.
    As the final application will not be too complicated I could rewrite this in C++, has anyone experience with latencies in this case?

    Thanks for any comments on this!

    Last edited by noleti; 2007-10-22 at 17:17. Reason: typo

  2. #2
    (Retired) Nokia Developer Admin.
    Join Date
    Jan 2006

    Re: Playback latency

    I moved this to the Java Media forum to see if they can help.


  3. #3
    Registered User
    Join Date
    Oct 2007

    Re: Playback latency

    I don't think the move was needed, but anyways:

    I finally have the Symbian C++ setup running and made some tests: I used the AudioStream Example from Nokia and played around with the sounds to be played. The default setting in this example is to play 40960 bytes as 16bit @8kHz. I changed the frequency to 48kHz to match my audio samples. Then I played these samples (e.g. pure sine etc.) All measurements are done on a E61i which has dual ARM9@200MHz

    I saw 2 problems:
    -although the playback should take 40960/(2*48) ms=426,667 ms, I only hear ~250ms of it with my recording PC. The beginning is played, but not the last stuff in the stream.
    - This is supported by the MaoscPlayComplete function being called ~380ms after the initial open() of the stream - less then the estimated playback time of ~420ms.

    Am I missing something here? Is this the behaviour to expect?

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