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Sample - playing silence via WASAPI event-driven (pull) mode

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This blog post has moved to https://matthewvaneerde.wordpress.com/2008/12/10/sample-playing-silence-via-wasapi-event-driven-pull-mode/

Comments

  • Anonymous
    July 28, 2009
    Useful article, but I suppose there is a bug in source code, look for correct version below:       hr = pAudioRenderClient->GetBuffer(nFramesInBuffer-nFramesOfPadding, &pData);        if (FAILED(hr)) {        hr = pAudioRenderClient->ReleaseBuffer(nFramesInBuffer-nFramesOfPadding, AUDCLNT_BUFFERFLAGS_SILENT);        if (FAILED(hr)) {

  • Anonymous
    July 30, 2009
    Yup.  Oops.

  • Anonymous
    July 30, 2009
    Fixed.

  • Anonymous
    December 12, 2009
    Yup, thanks, now works! Your articles helped me a lot.

  • Anonymous
    January 06, 2011
    Could it play sin wave ,and hit key to stop?

  • Anonymous
    January 08, 2011
    The comment has been removed

  • Anonymous
    May 11, 2011
    I'm working on loopback capture, to handle silent I want to try solution with playing silence all the time, but when I run it, silence is being played for a short moment and then is showing error "Got "feed me" event but IAudioClient::GetCurrentPadding reports buffer is full - glitch?n" What could be the cause? Regards

  • Anonymous
    May 12, 2011
    If you're getting "need more data" notifications but the buffer is full there's likely a glitch.  There are many possible causes; it could be a bug in the audio engine, in the audio driver, or it could be that some other process (probably a driver) is holding off the system. Can you take "glitch logs" and send them to me?  Follow the instructions in this thread: social.msdn.microsoft.com/.../1a796e5c-e808-42c0-96cd-84cebfaf71d5

  • Anonymous
    June 05, 2011
    Hi, I make a report as You wish. Report is from Windows 7. I follow all steps You mention in Your comment. Here are the results: www.sendspace.pl/.../aeab4dcf2712c9e0297982f I hope You can help to get me an idea why this is happening. I want to write DirectShow source filter with audio from speakers as source. But I need good way of starting recording from speakers when nothing is playing. I need record silence as a part of my recording. I found also an issue in Your blog. Always when I  post a comment first attempt is failed, I don't get any confirmation and comment is not showing in comments list, and I have to write again. In contact form I also found this issue. Regards

  • Anonymous
    June 14, 2011
    Hi mocdiv. Thank you for sending the glitch trace.  I looked at it with some of the glitch trace folks here and there appear to be two potentially related problems. The first problem is in my source - I'm registering for the Multimedia Class Scheduler Service, but under the wrong class.  An audio thread should register using the "Audio" or "Pro Audio" classes; I'm incorrectly registering using the "Playback" class. Can you change this code:    // register with MMCSS    DWORD nTaskIndex = 0;    HANDLE hTask = AvSetMmThreadCharacteristics(L"Playback", &nTaskIndex); to this:    // register with MMCSS    DWORD nTaskIndex = 0;    HANDLE hTask = AvSetMmThreadCharacteristics(L"Audio", &nTaskIndex); ? The second problem appears to be related to aqq.exe taking up too much of audiodg.exe's time.  Does this problem only reproduce when aqq.exe is running? If you like you can contact me directly at (mateer at microsoft dot com)

  • Anonymous
    February 24, 2017
    I had a question -- to check how the silence flag works, I put your silence.exe and a loopback capture executable that checks the flags returned in GetBuffer, and when I would start silence directed towards an endpoint and then did the loopback capture on that endpoint, the flags returned from GetBuffer did not have the silence bit set. I tried the same thing with Windows Media player, and when I would pause it my loopback capture did indicate that the silence flag was set. What am I missing in regards to the silence flag and loopback capture? Thanks!

    • Anonymous
      February 24, 2017
      It sounds like some audio processing object is clearing the flag between silence.exe and loopback-capture.exe. Arguably a bug.

  • Anonymous
    February 28, 2017
    Another question, related similar to the "Playback" vs "Audio" issue from a previous response -- I have another playback application that even when registering as "Pro Audio" will every so often indicate that GetCurrentPadding indicates a full buffer (using the same manner of detection as silence.exe). You mentioned previously that in the other user's case something was taking up a lot of audiodg.exe's time. How can I check for that (and see what it is that is taking up all the time if that is the case)?