Question

i have tried to get the sine wave example running on an AsioOut, but it sounds more like a distorted square wave. is it possible that the AsioOut only supports PCM formats? the asio .wav file playback works just fine…

If so, how can i fill my buffers with Ieee floats and convert to PCM? or whats the best way to palyback Ieee on ASIO? i would love to avoid unnecessary sample conversions..

in my code so far, i have tried to generate a sine wave which fits the buffer size, to make sure that i have continuous values, i initialize it with sample rate 44100 and 1 channel. then i pass an instance of the class to the Init() of my AsioOut:

public class SineWaveProvider32 : IWaveProvider
{
    private WaveFormat waveFormat;
    public WaveFormat WaveFormat
    {
        get
        {
            return this.waveFormat;
        }
    }

    public SineWaveProvider32() : this(44100, 1)
    {
    }

    public SineWaveProvider32(int sampleRate, int channels)
    {
        this.SetWaveFormat(sampleRate, channels);
    }

    public void SetWaveFormat(int sampleRate, int channels)
    {
        this.waveFormat = WaveFormat.CreateIeeeFloatWaveFormat(sampleRate, channels);
    }

            public unsafe int Read(byte[] buffer, int offset, int count)
    {
        var samples = count/4;
        fixed(byte* buff = buffer)
        {
            for (int n = 0; n < samples; n++)
            {
                var num = (float)(Math.Sin( (2 * Math.PI * n)/ samples ));
                ((float*)buff)[n] = num;
            }
        }

        return count;
    }
}

Answer 1

Ok i found the bug. Asio is somehow stereo by design. so this code works:

public class SineWaveProvider32 : IWaveProvider
{
    private WaveFormat waveFormat;
    public WaveFormat WaveFormat
    {
        get
        {
            return this.waveFormat;
        }
    }

    public SineWaveProvider32() : this(44100, 2)
    {
    }

    public SineWaveProvider32(int sampleRate, int channels)
    {
        this.SetWaveFormat(sampleRate, channels);
    }

    public void SetWaveFormat(int sampleRate, int channels)
    {
        this.waveFormat = WaveFormat.CreateIeeeFloatWaveFormat(sampleRate, channels);
    }

    public unsafe int Read(byte[] buffer, int offset, int count)
    {
        var samples = count/4;
        fixed(byte* buff = buffer)
        {
            for (int n = 0; n < samples; n+=2)
            {
                var num = (float)(Math.Sin( (2 * Math.PI * n * 3)/ samples ));
                ((float*)buff)[n] = 0;
                ((float*)buff)[n+1] = num;
            }
        }

        return count;
    }

}