public static void Encode(IAudioDecoder input, Stream output)
{
byte[] decodedSound = Decode(input);
int channels = input.GetFormat() == AudioFormat.Stereo16 ? 2 : 1;
int blockSize = channels * 1024;
var ima4Encoder = new Ima4Encoder();
var adpcmSound = ima4Encoder.Encode(decodedSound, channels, blockSize);
long numFrames = (decodedSound.Length / channels / 2);
int frequency = input.GetFrequency();
int averageBytesPerSecond = (int)(adpcmSound.Length * (long)frequency / numFrames);
int framesPerBlock = (blockSize - 4 * channels) * 8 / (4 * channels) + 1;
var bw = new BinaryWriter(output);
// RIFF chunk
bw.Write(Encoding.UTF8.GetBytes("RIFF"));
bw.Write(adpcmSound.Length + 44 - 8);
bw.Write(Encoding.UTF8.GetBytes("WAVE"));
// Fmt sub-chunk
bw.Write(Encoding.UTF8.GetBytes("fmt "));
bw.Write(20); // chunk size
bw.Write((ushort)WaveFormat.IMA_ADPCM); // format
bw.Write((ushort)channels);
bw.Write(frequency);
bw.Write(averageBytesPerSecond); // average bytes per seconds
bw.Write((ushort)(blockSize)); // block align
bw.Write((ushort)4); // bits per sample
bw.Write((ushort)channels);
bw.Write((ushort)framesPerBlock);
// Data sub-chunk
bw.Write(Encoding.UTF8.GetBytes("data"));
bw.Write(adpcmSound.Length);
// Write down the data
output.Write(adpcmSound, 0, adpcmSound.Length);
}
private bool FillBuffer(int buffer)
{
int totalRead = 0;
int needToRead = BufferSize / decoder.GetBlockSize();
while (true)
{
int actuallyRead = decoder.ReadBlocks(decodedData, totalRead, needToRead - totalRead);
totalRead += actuallyRead;
if (totalRead == needToRead || !looping)
{
break;
}
decoder.Rewind();
}
if (totalRead > 0)
{
ALFormat format = (decoder.GetFormat() == AudioFormat.Stereo16) ? ALFormat.Stereo16 : ALFormat.Mono16;
int dataSize = totalRead * decoder.GetBlockSize();
AL.BufferData(buffer, format, decodedData, dataSize, decoder.GetFrequency());
return(true);
}
return(false);
}
