error in realtime wasapi capture(from sound card) manipulate and play

Question

I'm trying to capture all sound going through the computer to manipulate and play it in realTime (there can be a slight delay due to manipulation but nothing too serious).

I'm trying to do this using Naudio wasapi. The problem is: When I do it in exclusive mode, this line: audioClient.Initialize(shareMode, AudioClientStreamFlags.EventCallback, latencyRefTimes, latencyRefTimes,outputFormat, Guid.Empty);

throws this exception:

An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in NAudio.dll

Additional information: HRESULT: 0x88890016

When I do it in shared mode I get lot of noise which I think is caused by sound feedback (similiar to what happens when recording and playing at the same time)

Here's my code:

WasapiLoopbackCapture source = new WasapiLoopbackCapture();

        source.DataAvailable += CaptureOnDataAvailable;

        bufferedWaveProvider = new BufferedWaveProvider(source.WaveFormat);

        volumeProvider = new VolumeSampleProvider(bufferedWaveProvider.ToSampleProvider());

        WasapiOut soundOut = new WasapiOut(AudioClientShareMode.Shared, 0);

        soundOut.Init(volumeProvider);
        soundOut.Play();

        source.StartRecording();

        soundOut.Volume = 0.5f;
    }

    private void CaptureOnDataAvailable(object sender, WaveInEventArgs waveInEventArgs)
    {

        int length = waveInEventArgs.Buffer.Length;

        byte[] byteSamples = new Byte[length];
        float[] buffer = waveInEventArgs.Buffer.toFloatArray(waveInEventArgs.BytesRecorded);//buffer to contains the samples about to be manipulated


        fixer.fixSamples(length / 2, buffer, ref fixedSamples);


        if (fixedSamples.Count > 0)
        {
            //convert the fixed samples back to bytes in order for them to be able to play out
            byteSamples = fixedSamples.convertToByteArray(position);

            bufferedWaveProvider.AddSamples(byteSamples, 0, byteSamples.Length);
            volumeProvider.Volume = .5f;
        }

        position = fixedSamples.Count;

    }

How can I solve these problems?

Also, I don't know if it's the best approach for what i'm trying to do, so if anyone has a better idea how to do this I'm more than happy to hear. (i thought about using asio, but decided not to since there are a lot of computers without an asio driver)

Answer 1

this error is AUDCLNT_E_UNSUPPORTED_FORMAT You can only capture audio in certain formats with WASAPI. Usually has to be IEEE float, stereo, 44.1kHz / 48kHz