// 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();
}
}
}
void UnpackInfo(OggBitStream input)
{
Version = input.ReadInt32();
if (Version != 0)
{
throw new InvalidDataException("Invalid Vorbis encoder version.");
}
Channels = input.ReadUInt8();
Rate = input.ReadInt32();
BitrateUpper = input.ReadInt32();
BitrateNominal = input.ReadInt32();
BitrateLower = input.ReadInt32();
CodecSetup.BlockSizes[0] = 1 << input.ReadBits(4);
CodecSetup.BlockSizes[1] = 1 << input.ReadBits(4);
if (input.ReadBits(1) != 1)
{
throw InvalidHeader();
}
}
void UnpackBooks(OggBitStream input)
{
// codebooks
CodecSetup.Books = input.ReadUInt8() + 1;
if (CodecSetup.Books <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < CodecSetup.Books; ++i)
{
var param = StaticBookUnpack(input);
if (null == param)
{
throw InvalidHeader();
}
CodecSetup.BookParam[i] = param;
}
// time backend settings; hooks are unused
int times = input.ReadBits(6) + 1;
if (times <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < times; ++i)
{
int test = input.ReadBits(16);
if (test < 0 || test >= TimeB)
{
throw InvalidHeader();
}
}
// floor backend settings
CodecSetup.Floors = input.ReadBits(6) + 1;
if (CodecSetup.Floors <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < CodecSetup.Floors; i++)
{
int floor_type = input.ReadBits(16);
if (floor_type < 0 || floor_type >= FloorB)
{
throw InvalidHeader();
}
CodecSetup.FloorType[i] = floor_type;
var param = FloorMethods[floor_type] (input);
if (null == param)
{
throw InvalidHeader();
}
CodecSetup.FloorParam[i] = param;
}
// residue backend settings
CodecSetup.Residues = input.ReadBits(6) + 1;
if (CodecSetup.Residues <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < CodecSetup.Residues; ++i)
{
int residue_type = input.ReadBits(16);
if (residue_type < 0 || residue_type >= ResB)
{
throw InvalidHeader();
}
CodecSetup.ResidueType[i] = residue_type;
var param = UnpackResidue(input);
if (null == param)
{
throw InvalidHeader();
}
CodecSetup.ResidueParam[i] = param;
}
// map backend settings
CodecSetup.Maps = input.ReadBits(6) + 1;
if (CodecSetup.Maps <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < CodecSetup.Maps; ++i)
{
int map_type = input.ReadBits(16);
if (map_type < 0 || map_type >= MapB)
{
throw InvalidHeader();
}
CodecSetup.MapType[i] = map_type;
var param = UnpackMapping(input);
if (null == param)
{
throw InvalidHeader();
}
CodecSetup.MapParam[i] = param;
}
// mode settings
CodecSetup.Modes = input.ReadBits(6) + 1;
if (CodecSetup.Modes <= 0)
{
throw InvalidHeader();
}
for (int i = 0; i < CodecSetup.Modes; ++i)
{
CodecSetup.ModeParam[i].BlockFlag = input.ReadBits(1);
CodecSetup.ModeParam[i].WindowType = input.ReadBits(16);
CodecSetup.ModeParam[i].TransformType = input.ReadBits(16);
CodecSetup.ModeParam[i].Mapping = input.ReadBits(8);
if (CodecSetup.ModeParam[i].WindowType >= WindowB ||
CodecSetup.ModeParam[i].TransformType >= WindowB ||
CodecSetup.ModeParam[i].Mapping >= CodecSetup.Maps ||
CodecSetup.ModeParam[i].Mapping < 0)
{
throw InvalidHeader();
}
}
if (input.ReadBits(1) != 1)
{
throw InvalidHeader();
}
}