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  1. #1
    Registered User
    Join Date
    Oct 2007
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    5

    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!

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

  2. #2
    (Retired) Nokia Developer Admin.
    Join Date
    Jan 2006
    Location
    Michigan
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    4,664

    Re: Playback latency

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

    Ron

  3. #3
    Registered User
    Join Date
    Oct 2007
    Posts
    5

    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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