public void WriteChunk(byte[] chunk, uint timeStamp)
{
if (chunk.Length < 1)
{
return;
}
if (chunk[0] == 0)
{
// Header
if (chunk.Length < 3)
{
return;
}
ulong bits = (ulong)BigEndianBitConverter.ToUInt16(chunk, 1) << 48;
aacProfile = BitHelper.Read(ref bits, 5) - 1;
sampleRateIndex = BitHelper.Read(ref bits, 4);
channelConfig = BitHelper.Read(ref bits, 4);
if (aacProfile < 0 || aacProfile > 3)
{
throw new AudioExtractionException("Unsupported AAC profile.");
}
if (sampleRateIndex > 12)
{
throw new AudioExtractionException("Invalid AAC sample rate index.");
}
if (channelConfig > 6)
{
throw new AudioExtractionException("Invalid AAC channel configuration.");
}
}
else
{
// Audio data
int dataSize = chunk.Length - 1;
ulong bits = 0;
// Reference: WriteADTSHeader from FAAC's bitstream.c
BitHelper.Write(ref bits, 12, 0xFFF);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 2, 0);
BitHelper.Write(ref bits, 1, 1);
BitHelper.Write(ref bits, 2, aacProfile);
BitHelper.Write(ref bits, 4, sampleRateIndex);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 3, channelConfig);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 1, 0);
BitHelper.Write(ref bits, 13, 7 + dataSize);
BitHelper.Write(ref bits, 11, 0x7FF);
BitHelper.Write(ref bits, 2, 0);
fileStream.Write(BigEndianBitConverter.GetBytes(bits), 1, 7);
fileStream.Write(chunk, 1, dataSize);
}
}
