BufferCB not being called by SampleGrabber

问题

I'm using a SampleGrabber to get audio data, however my BufferCB method is not being executed. What am I doing wrong ?

//add Sample Grabber
            IBaseFilter pSampleGrabber = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_SampleGrabber));
            hr = pGraph.AddFilter(pSampleGrabber, "SampleGrabber");
            checkHR(hr, "Can't add Sample Grabber");

        AMMediaType pSampleGrabber_pmt = new AMMediaType();
        //pSampleGrabber_pmt.majorType = MediaType.Audio;
        pSampleGrabber_pmt.subType = MediaSubType.PCM;
        pSampleGrabber_pmt.formatType = FormatType.WaveEx;
        pSampleGrabber_pmt.fixedSizeSamples = true;
        pSampleGrabber_pmt.formatSize = 18;
        pSampleGrabber_pmt.sampleSize = 2;

        WaveFormatEx pSampleGrabber_Format = new WaveFormatEx();
        pSampleGrabber_Format.wFormatTag = 1;
        pSampleGrabber_Format.nChannels = 1;
        pSampleGrabber_Format.nSamplesPerSec = 48000;
        pSampleGrabber_Format.nAvgBytesPerSec = 96000;
        pSampleGrabber_Format.nBlockAlign = 2;
        pSampleGrabber_Format.wBitsPerSample = 16;
        pSampleGrabber_pmt.formatPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(pSampleGrabber_Format));
        Marshal.StructureToPtr(pSampleGrabber_Format, pSampleGrabber_pmt.formatPtr, false);
        hr = ((ISampleGrabber)pSampleGrabber).SetMediaType(pSampleGrabber_pmt);
        DsUtils.FreeAMMediaType(pSampleGrabber_pmt);
        checkHR(hr, "Can't set media type to sample grabber");

        ISampleGrabber pGrabber = new SampleGrabber() as ISampleGrabber; 
        pGrabber = (ISampleGrabber)pSampleGrabber;
        pGrabber.SetCallback(null, 1);

My BufferCB method is like

public int BufferCB(double SampleTime, IntPtr pBuffer, int BufferLen)
        {

            return 0;
        }

回答1:

You created and configured one instance pSampleGrabber and then you are attaching your callback to another unused idling instance pGrabber.

You need

pSampleGrabber as ISampleGrabber

instead of

new SampleGrabber() as ISampleGrabber

来源：https://stackoverflow.com/questions/10829575/buffercb-not-being-called-by-samplegrabber