public IEnumerable<AudioChunk> StreamData( Stream source )
{
PrimitiveReader reader = new PrimitiveReader( source );
reader.BigEndian = true;
while( true ) {
#region Frame header
FlacBitReader bitReader = new FlacBitReader( reader );
bitReader.BigEndian = true;
int syncCode = bitReader.ReadBits( 14 );
if( syncCode != 0x3FFE ) {
throw new InvalidDataException( "Invalid synchronisation code." );
}
int reserved = bitReader.ReadBit();
bool variableBlockSize = bitReader.ReadBit() != 0;
int blockSizeFlags = bitReader.ReadBits( 4 );
int sampleRateFlags = bitReader.ReadBits( 4 );
int channelAssignment = bitReader.ReadBits( 4 );
int sampleSizeFlags = bitReader.ReadBits( 3 );
if( bitReader.ReadBit() != 0 )
throw new InvalidDataException( "Reserved bit is not 0." );
byte[] numberData = ReadRawUTF8Char( reader );
/*int frameNumber = numberData[0];
for( int i = 1; i < numberData.Length; i++ ) {
frameNumber <<= 6;
frameNumber |= numberData[i];
}
Console.WriteLine( frameNumber );*/
int blockSize = 0;
if( blockSizeFlags == 0x0 ) {
throw new InvalidDataException( "0 is reserved for block sizes." );
} else if( blockSizeFlags == 0x1 ) {
blockSize = 192;
} else if( blockSizeFlags >= 0x2 && blockSizeFlags <= 0x5 ) {
blockSize = 576 * ( 1 << ( blockSizeFlags - 2 ) ); // 2^x.
} else if( blockSizeFlags == 0x6 ) {
blockSize = reader.ReadByte() + 1;
} else if( blockSizeFlags == 0x7 ) {
blockSize = reader.ReadUInt16() + 1;
} else {
blockSize = 256 * ( 1 << ( blockSizeFlags - 8 ) ); // 2^x.
}
int sampleRate = 0;
if( sampleRateFlags == 0x0 ) {
sampleRate = metaSampleRate;
} else if( sampleRateFlags >= 0x01 && sampleRateFlags <= 0xB ) {
sampleRate = sampleRates[sampleRateFlags];
} else if( sampleRateFlags == 0xC ) {
sampleRate = reader.ReadByte();
} else if( sampleRateFlags == 0xD ) {
sampleRate = reader.ReadUInt16();
} else if( sampleRateFlags == 0xE ) {
sampleRate = reader.ReadUInt16() * 10;
} else {
throw new InvalidDataException( "Invalid sample rate flag." );
}
int bitsPerSample;
if( sampleSizeFlags == 0 ) {
bitsPerSample = metaBitsPerSample;
} else if( sampleSizeFlags == 0x3 || sampleRateFlags == 0x7 ) {
throw new InvalidDataException( "Sample size is reserved." );
} else {
bitsPerSample = bitSampleSizes[sampleSizeFlags];
}
int channelsCount;
ChannelAssignment soundAssignment = (ChannelAssignment)channelAssignment;
if( channelAssignment < 0x08 ) {
channelsCount = channelAssignment + 1;
} else if( channelAssignment < 0x0B ) {
channelsCount = 2;
} else {
throw new InvalidDataException( "Channel assignment values > 1010 are reserved." );
}
byte crc8 = reader.ReadByte();
#endregion
#region Subframe
int[][] channelsData = new int[channelsCount][];
for( int i = 0; i < channelsCount; i++ ) {
if( bitReader.ReadBit() != 0 ) {
throw new InvalidDataException( "Padding bit should be 0." );
}
int[] channelData = null;
int subframeType = bitReader.ReadBits( 6 );
bool wastedBitsPerSampleFlag = bitReader.ReadBit() != 0;
int adjustedBitsPerSample = bitsPerSample;
switch( soundAssignment ) {
case ChannelAssignment.LeftSide:
if( i == 1 ) adjustedBitsPerSample++;
break;
case ChannelAssignment.RightSide:
if( i == 0 ) adjustedBitsPerSample++;
break;
case ChannelAssignment.MidSide:
if( i == 1 ) adjustedBitsPerSample++;
break;
}
int wastedBitsPerSample = 0;
if( wastedBitsPerSampleFlag ) {
wastedBitsPerSample = 1 + bitReader.ReadUnary();
}
if( subframeType == 0x00 ) {
channelData = ProcessConstantSubframe( bitReader, adjustedBitsPerSample, blockSize );
} else if( subframeType == 0x01 ) {
channelData = ProcessVerbatimSubframe( bitReader, adjustedBitsPerSample, blockSize );
} else {
if( ( subframeType & 0x20 ) != 0 ) {
int order = ( subframeType & 0x1F ) + 1;
channelData = ProcessLpcSubframe( bitReader, adjustedBitsPerSample, order, blockSize );
} else if( ( subframeType & 0x08 ) != 0 ) {
int order = subframeType & 0x07;
channelData = ProcessFixedSubframe( bitReader, adjustedBitsPerSample, order, blockSize );
}
}
channelsData[i] = channelData;
}
bitReader.SkipRemainingBits();
#endregion
// Transform the samples into left right
switch( soundAssignment ) {
case ChannelAssignment.LeftSide:
TransformSamplesLS( channelsData[0], channelsData[1] );
break;
case ChannelAssignment.RightSide:
TransformSamplesSR( channelsData[0], channelsData[1] );
break;
case ChannelAssignment.MidSide:
TransformSamplesMS( channelsData[0], channelsData[1] );
break;
}
int bytesPerSample = (int)Math.Ceiling( bitsPerSample / 8.0 );
byte[] data = new byte[channelsCount * bytesPerSample * blockSize];
bool use16Bits = bitsPerSample <= 16;
bool use8Bits = bitsPerSample <= 8;
int offset = 0;
for( int i = 0; i < blockSize; i++ ) {
for( int ch = 0; ch < channelsCount; ch++ ) {
int[] channelData = channelsData[ch];
if( use16Bits ) {
ushort sample = (ushort)channelData[i];
data[offset++] = (byte)( sample );
data[offset++] = (byte)( sample >> 8 );
} else if( use8Bits ) {
data[offset++] = (byte)channelData[i];
}
}
}
// Read frame footer
ushort crc16 = reader.ReadUInt16();
AudioChunk chunk = new AudioChunk();
chunk.Frequency = sampleRate;
chunk.Channels = channelsCount;
chunk.BitsPerSample = bitsPerSample;
chunk.Data = data;
yield return chunk;
}
}
