/* Attempts to read the riff chunk from a given
* stream of bytes, returns the ChunkSize if successful */
//TODO add custom exception
public static uint ReadRiffChunk(List <byte> lData)
{
if (lData.Count() < RiffChunkSize)
{
throw new Exception("Not enough bytes available to read the Riff Chunk");
}
var data = lData.Take(RiffChunkSize).ToArray();
// Chunk Id should contain the ascii string "RIFF" in Big Endian format
if (EndianHelper.ToUInt32BE(data, 0) != 0x52494646)
{
throw new Exception("Unable to read WAVE file");
}
// Read In Size of Chunk in Little Endian Format
uint chunkSize = EndianHelper.ToUInt32LE(data, 4);
// Format should contain the ascii string "WAVE" in Big Endian format
if (EndianHelper.ToUInt32BE(data, 8) != 0x57415645)
{
throw new Exception("Unable to read WAVE file");
}
return(chunkSize);
}
public static List <short> ReadDataChunk(List <byte> lData)
{
var data = lData.ToArray();
// Could be a "List" Chunk prepending
if (EndianHelper.ToUInt32BE(data, 0) == 0x4C495354)
{
data = data.Skip(78).ToArray();
lData.RemoveRange(0, 78);
}
// Chunk ID should contain the letters "data" in Big Endian format
if (EndianHelper.ToUInt32BE(data, 0) != 0x64617461)
{
throw new Exception("Unable to read Data Chunk, incorrect ID");
}
// Number of bytes containing pure sample data
uint dataSize = EndianHelper.ToUInt32LE(data, 4);
/* Check data size is a multiple of 2, as samples are 16bits each. Also
* check there's enough bytes left in the buffer to extract the sample data */
if ((dataSize & 0x1) != 0x0 || dataSize > int.MaxValue || dataSize > lData.Count() - 8)
{
Debug.WriteLine((dataSize & 0x1) + " " + dataSize + " " + lData.Count());
throw new Exception("Unable to read Data Chunk");
}
var sampleData = new List <short>();
lData.RemoveRange(0, 8);
for (int i = 0; i < dataSize; i += 2)
{
sampleData.Add(BitConverter.IsLittleEndian ?
(short)(lData[i] | lData[i + 1] << 8) :
(short)(lData[i + 1] | lData[i] << 8));
}
return(sampleData);
}
public FormatChunk(List <byte> lData)
{
if (lData.Count() < FormatChunkSize)
{
throw new Exception("Not enough bytes for reading the Format Chunk");
}
var data = lData.Take(FormatChunkSize).ToArray();
// SubChunk ID should contain the ascii string "fmt " in Big Endian format
if (EndianHelper.ToUInt32BE(data, 0) != 0x666D7420)
{
throw new Exception("Unable to read Format Chunk");
}
/* Check SubChunk Size is 16 for PCM. currently only supporting PCM at the moment,
* so fail on any other sizes */
if (EndianHelper.ToUInt32LE(data, 4) != 0x10)
{
throw new Exception("Non PCM format non-supported");
}
/* Check Audio Format is for PCM (value of 1). Current only supporting PCM at the moment,
* so fail on any other values */
if (EndianHelper.ToUInt16LE(data, 8) != 0x1)
{
throw new Exception("Non PCM format non-supported");
}
// Check if Mono(1) or Stereo(2) number of channels
ushort nChannels = EndianHelper.ToUInt16LE(data, 10);
if (nChannels != 1 && nChannels != 2)
{
throw new Exception("Unable to read Format Chunk");
}
NChannels = nChannels == 1 ? NumChannels.Mono : NumChannels.Stereo;
// Get Sample Rate
SampleRate = EndianHelper.ToUInt32LE(data, 12);
/* Get Byte Rate, in PCM this is redundant as it's equal to
* SampleRate * NumChannels * BitsPerSample/8. */
ByteRate = EndianHelper.ToUInt32LE(data, 16);
/* Get Block Align, again in PCM this is redundant as it's equal to
* NumChannels * BitsPerSample/8 */
BlockAlign = EndianHelper.ToUInt16LE(data, 20);
// Get Bits Per Sample, in PCM should be rounded up to the next 8 bits
ushort bitsPerSample = EndianHelper.ToUInt16LE(data, 22);
bitsPerSample += (ushort)(bitsPerSample % 8);
BitsPerSample = bitsPerSample;
/* For validity check ByteRate = SampleRate * nChannels * BitsPerSample/8*/
if (ByteRate != SampleRate * nChannels * (BitsPerSample / 8))
{
throw new Exception("Unable to read Format Chunk");
}
/* For validity check BlockAlign = nChannels * BitsPerSample/8*/
if (BlockAlign != nChannels * (BitsPerSample / 8))
{
throw new Exception("Unable to read Format Chunk");
}
}
