public void Decode(Stream input, Stream output, bool resample)
{
int resampleRate = 44100;
using OggReader reader = new OggReader(input);
using BinaryWriter writer = new BinaryWriter(output, System.Text.Encoding.ASCII, true);
using var decoder = OpusDecoder.Create(48000, reader.Channels);
LibResampler resampler = null;
if (resample)
{
resampler = new LibResampler(48000, resampleRate, reader.Channels);
}
bool isFirst = true;
long headerPosition = output.Position;
output.Position += 44;
Span <float> inputBuffer = default;
while (!reader.IsStreamFinished)
{
var frame = reader.ReadPacket();
if (isFirst)
{
inputBuffer = new float[decoder.GetSamples(frame.Span) * decoder.OutputChannels];
}
decoder.DecodeFloat(frame.Span, inputBuffer, out int dataLength);
var outputSamples = inputBuffer.Slice(0, dataLength);
if (isFirst)
{
//remove preskip
outputSamples = outputSamples.Slice(reader.Preskip);
isFirst = false;
}
Span <float> outputSpan = outputSamples;
if (resample)
{
float[] resampledSamples = new float[resampler.ResampleUpperBound(outputSamples.Length)];
resampler.Resample(outputSamples, resampledSamples, reader.IsStreamFinished, out int outputLength);
outputSpan = resampledSamples.AsSpan(0, outputLength);
}
foreach (float sample in outputSpan)
{
writer.Write(WaveWriter.ConvertSample(sample));
}
}
long endPosition = output.Position;
output.Position = headerPosition;
WaveWriter.WriteWAVHeader(output, reader.Channels, (int)(endPosition - headerPosition), resample ? resampleRate : 48000, 16);
output.Position = endPosition;
}