private void ThrowExceptionForError(int error)
{
if (error != 0)
{
throw new Exception(InteropWrapper.src_strerror(error));
}
}
/// <summary>
/// Sets the resampling ratio. Multiplying the input rate with the ratio factor results in the output rate.
/// </summary>
/// <param name="ratio">the resampling ratio</param>
/// <param name="step">true for an instant change in the ratio, false for a gradual linear change during the next #Process call</param>
public void SetRatio(double ratio, bool step)
{
if (step)
{
// force the ratio for the next #Process call instead of linearly interpolating from the previous
// ratio to the current ratio
error = InteropWrapper.src_set_ratio(srcState, ratio);
ThrowExceptionForError(error);
}
this.ratio = ratio;
}
/// <summary>
/// Creates a new resampler instance with the supplied converter type (which equals the resampling quality)
/// for a supplied number of channels.
/// </summary>
/// <param name="type">the type of the internal conversion algorithm (quality level)</param>
/// <param name="channels">the number of channels that will be provided to the processing method</param>
public SampleRateConverter(ConverterType type, int channels)
{
srcState = InteropWrapper.src_new(type, channels, out error);
ThrowExceptionForError(error);
srcData = new SRC_DATA();
SetRatio(1d);
this.channels = channels;
this.bufferedSamples = 0;
}
/// <summary>
/// Disposes this instance of the resampler, freeing its memory.
/// </summary>
public void Dispose()
{
if (srcState != IntPtr.Zero)
{
srcState = InteropWrapper.src_delete(srcState);
if (srcState != IntPtr.Zero)
{
throw new Exception("could not delete the sample rate converter");
}
}
}
private unsafe void Process(float *input, int inputLength, float *output, int outputLength,
bool endOfInput, out int inputLengthUsed, out int outputLengthGenerated)
{
srcData.data_in = input;
srcData.data_out = output;
srcData.end_of_input = endOfInput ? 1 : 0;
srcData.input_frames = inputLength / channels;
srcData.output_frames = outputLength / channels;
srcData.src_ratio = ratio;
error = InteropWrapper.src_process(srcState, ref srcData);
ThrowExceptionForError(error);
inputLengthUsed = srcData.input_frames_used * channels;
outputLengthGenerated = srcData.output_frames_gen * channels;
bufferedSamples += inputLengthUsed - (outputLengthGenerated / ratio);
}
/// <summary>
/// Resets the resampler, which essentially clears the internal buffer.
/// </summary>
public void Reset()
{
error = InteropWrapper.src_reset(srcState);
ThrowExceptionForError(error);
bufferedSamples = 0;
}
/// <summary>
/// Checks if a given resampling ratio is valid.
/// </summary>
/// <param name="ratio">true if the ratio is valid, else false</param>
/// <returns></returns>
public static bool CheckRatio(double ratio)
{
return(InteropWrapper.src_is_valid_ratio(ratio) == 1);
}