Live Audio Stream is Delayed

Question

I'm creating a kind of live video streaming application and using a number of different libraries. I'm using NAudio for unpacking the audio stream as it comes in. I found on their discussion boards this thread which I utilised like so;

    BufferedWaveProvider mybufferwp = null;
    WaveOut wo = new WaveOut();
    WaveFormat wf = new WaveFormat(16000, 1);

    void MainWindow()
    {
    _audioClient = new AudioClient();
    _audioClient.AudioFrameReady += _audioClient_AudioFrameReady;
    _audioClient.Connect(parent.TempIp, parent.AudioPort);

    mybufferwp = new BufferedWaveProvider(wf);
    mybufferwp.BufferDuration = TimeSpan.FromMinutes(5);
    wo.Init(mybufferwp);
    wo.Play();
    }

    void _audioClient_AudioFrameReady(object sender, AudioFrameReadyEventArgs e)
    {
        if (mybufferwp != null)
        {
            mybufferwp.AddSamples(e.AudioFrame.AudioData, 0, e.AudioFrame.AudioData.Length);
        }
    }

My problem is that the audio is slightly delayed. Not by much granted but its noticeable and I was hoping there might be something I could do to get it more in sync with my video feed which is nearly perfectly live.

Extra Info AudioClient is from Kinect Service which allows me to send and receive Kinect Camera Data.

score 1 · Answer 1 · answered Jun 17 '13 at 08:13

The problem you are dealing with is called latency. There are two sources of latency in this system. The first is the size of the record buffer. The Kinect will be filling a buffer of audio and then raising its AudioFrameReady event. The larger the buffer size (in milliseconds), the longer the delay will be. I don't know if Kinect gives you an option to minimise the size of this buffer.

Then there is more buffering on the playback side. NAudio's default setup for WaveOut is two buffers of 100ms each - one is played back while the other is filled. This value is chosen for smooth playback- make the buffers too small and playback might stutter. However, it is fully configurable, so I'd suggest reducing the WaveOut buffer sizes until playback starts to break up.

Live Audio Stream is Delayed

1 Answers1