private void ParseRiff(byte[] bytes)
{
Sanity.Requires(bytes.Length >= 44, "File size less than 44 bytes.");
Sanity.Requires(Encoding.ASCII.GetString(bytes, 0, 4) == "RIFF", "File is not RIFF.");
Sanity.Requires(Encoding.ASCII.GetString(bytes, 8, 4) == "WAVE", "File is not WAVE.");
ParseChunk(bytes, 12);
PostProcess();
}
private void ParseFormat()
{
Sanity.Requires(FormatChunk.Size >= 16, "Format chunk is less than 16.");
AudioTypeId = BitConverter.ToInt16(Bytes, FormatChunk.Offset + 8);
NumChannels = BitConverter.ToInt16(Bytes, FormatChunk.Offset + 10);
SampleRate = BitConverter.ToInt32(Bytes, FormatChunk.Offset + 12);
ByteRate = BitConverter.ToInt32(Bytes, FormatChunk.Offset + 16);
BlockAlign = BitConverter.ToInt16(Bytes, FormatChunk.Offset + 20);
BitsPerSample = BitConverter.ToInt16(Bytes, FormatChunk.Offset + 22);
Sanity.Requires((BitsPerSample & 7) == 0, "Bits per sample is not a multiple of 8.");
Sanity.Requires(ByteRate == (NumChannels * SampleRate * BitsPerSample) >> 3, "Byte rate, channel, sample rate, bits per sampel error.");
Sanity.Requires(BlockAlign == NumChannels * BitsPerSample >> 3, "Block align, channel, bits per sample error.");
}
private void ParseChunk(byte[] bytes, int offset)
{
// A valid audio.
if (offset == bytes.Length)
{
return;
}
// Ignore the uncomplete chunk. Since we only shallow parse here.
if (offset + 8 > bytes.Length)
{
return;
}
string chunkName = Encoding.ASCII.GetString(bytes, offset, 4);
int chunkSize = BitConverter.ToInt32(bytes, offset + 4);
bool complete = offset + 8 + chunkSize <= bytes.Length;
Chunk chunk = new Chunk {
Name = chunkName, Offset = offset, Size = chunkSize, Complete = complete
};
if (chunk.Name == "fmt ")
{
Sanity.Requires(complete, "Format chunk is imcomplete.");
Sanity.Requires(FormatChunk.Name == "", "More than one format chunk.");
FormatChunk = chunk;
}
else if (chunk.Name == "data")
{
Sanity.Requires(DataChunk.Name == "", "More than one data chunk.");
DataChunk = chunk;
}
ChunkList.Add(chunk);
if (complete)
{
ParseChunk(bytes, offset + 8 + chunkSize);
}
}
public void PostProcess()
{
Sanity.Requires(FormatChunk.Name != "", "Missing format chunk.");
Sanity.Requires(DataChunk.Name != "", "Missing data chunk.");
ParseFormat();
}