public OggBitStream(OggPacket input)
{
// certainly an overhead to create a new stream for every packet, but it's so convenient
var buf = new MemoryStream(input.Packet);
m_input = new LsbBitStream(buf);
}
// https://www.xiph.org/vorbis/doc/libvorbis/vorbis_packet_blocksize.html
public int PacketBlockSize(OggPacket op)
{
using (var input = new OggBitStream(op))
{
// Check the packet type
if (input.ReadBits(1) != 0)
{
throw new InvalidDataException("Not an audio data packet.");
}
int modebits = 0;
for (int v = CodecSetup.Modes; v > 1; v >>= 1)
{
modebits++;
}
// read our mode and pre/post windowsize
int mode = input.ReadBits(modebits);
if (-1 == mode)
{
throw new InvalidDataException("Invalid Ogg/Vorbis packet.");
}
return(CodecSetup.BlockSizes[CodecSetup.ModeParam[mode].BlockFlag]);
}
}
public bool PacketIn(OggPacket op)
{
int bytes = op.Packet.Length;
int lacing_vals = bytes / 255 + 1;
if (BodyReturned > 0)
{
// advance packet data according to the body_returned pointer.
// We had to keep it around to return a pointer into the buffer last call.
BodyFill -= BodyReturned;
if (BodyFill > 0)
{
Buffer.BlockCopy(BodyData, BodyReturned, BodyData, 0, BodyFill);
}
BodyReturned = 0;
}
// make sure we have the buffer storage
if (!BodyExpand(bytes) || !LacingExpand(lacing_vals))
{
return(false);
}
// Copy in the submitted packet.
Buffer.BlockCopy(op.Packet, 0, BodyData, BodyFill, op.Packet.Length);
BodyFill += op.Packet.Length;
// Store lacing vals for this packet
int i;
for (i = 0; i < lacing_vals - 1; ++i)
{
LacingVals[LacingFill + i] = 0xFF;
GranuleVals[LacingFill + i] = GranulePos;
}
LacingVals[LacingFill + i] = bytes % 0xFF;
GranulePos = GranuleVals[LacingFill + i] = op.GranulePos;
// flag the first segment as the beginning of the packet
LacingVals[LacingFill] |= 0x100;
LacingFill += lacing_vals;
PacketNo++;
EoS = op.EoS;
return(true);
}
// https://xiph.org/vorbis/doc/libvorbis/vorbis_synthesis_headerin.html
public void SynthesisHeaderin(VorbisComment vc, OggPacket op)
{
using (var input = new OggBitStream(op))
{
int packtype = input.ReadUInt8();
var buf = input.ReadBytes(6);
if (!buf.AsciiEqual("vorbis"))
{
throw new InvalidDataException("Not an Ogg/Vorbis stream.");
}
switch (packtype)
{
case 1:
if (!op.BoS)
{
throw InvalidHeader();
}
if (Rate != 0)
{
throw InvalidHeader();
}
UnpackInfo(input);
break;
case 3:
if (0 == Rate)
{
throw InvalidHeader();
}
vc.UnpackComment(input);
break;
case 5:
if (0 == Rate || null == vc.Vendor)
{
throw InvalidHeader();
}
UnpackBooks(input);
break;
default:
throw InvalidHeader();
}
}
}
// https://xiph.org/vorbis/doc/libvorbis/vorbis_commentheader_out.html
public void HeaderOut(OggPacket packet)
{
using (var buf = new MemoryStream())
using (var output = new BinaryWriter(buf))
{
// preamble
output.Write((byte)3);
output.Write("vorbis".ToCharArray());
// vendor
output.Write(EncodeVendorString.Length);
output.Write(EncodeVendorString);
// comments
output.Write(Comments.Count);
foreach (var comment in Comments)
{
if (comment != null && comment.Length > 0)
{
output.Write(comment.Length);
output.Write(comment);
}
else
{
output.Write(0);
}
}
output.Write((byte)1);
output.Flush();
packet.SetPacket(1, buf.ToArray());
packet.BoS = false;
packet.EoS = false;
packet.GranulePos = 0;
}
}
