public Stream GetStream(string filename)
{
IdxEntry entry;
if (!index.TryGetValue(filename, out entry))
{
return(null);
}
s.Seek(entry.Offset, SeekOrigin.Begin);
var waveHeaderMemoryStream = new MemoryStream();
var channels = (entry.Flags & 1) > 0 ? 2 : 1;
if ((entry.Flags & 2) > 0)
{
// PCM
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("RIFF"));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.Length + 36));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("WAVE"));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("fmt "));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(16));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)1));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)channels));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.SampleRate));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(2 * channels * entry.SampleRate));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)(2 * channels)));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)16));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("data"));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.Length));
}
if ((entry.Flags & 8) > 0)
{
// IMA ADPCM
var samplesPerChunk = (2 * (entry.ChunkSize - 4)) + 1;
var bytesPerSec = (int)Math.Floor(((double)(2 * entry.ChunkSize) / samplesPerChunk) * ((double)entry.SampleRate / 2));
var chunkSize = entry.ChunkSize > entry.Length ? entry.Length : entry.ChunkSize;
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("RIFF"));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.Length + 52));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("WAVE"));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("fmt "));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(20));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)17));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)channels));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.SampleRate));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(bytesPerSec));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)chunkSize));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)4));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)2));
waveHeaderMemoryStream.Write(BitConverter.GetBytes((short)samplesPerChunk));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("fact"));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(4));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(4 * entry.Length));
waveHeaderMemoryStream.Write(Encoding.ASCII.GetBytes("data"));
waveHeaderMemoryStream.Write(BitConverter.GetBytes(entry.Length));
}
waveHeaderMemoryStream.Seek(0, SeekOrigin.Begin);
// Construct a merged stream
var mergedStream = new MergedStream(waveHeaderMemoryStream, s);
mergedStream.SetLength(waveHeaderMemoryStream.Length + entry.Length);
return(mergedStream);
}
