private void ValidateTable(BitSplitter bs)
{
int pointer = (int)bs.GetInteger(8);
if (pointer != 0)
{
throw new DemuxException("Non-zero pointers are not currently supported");
}
int table_id = (int)bs.GetInteger(8);
if (table_id != 0x02)
{
throw new DemuxException("Wrong table ID for PMT");
}
SectionSyntax = bs.GetFlag();
if (!SectionSyntax)
{
throw new DemuxException("Invalid PMT: incorrect section syntax");
}
bool zero = bs.GetFlag();
if (zero)
{
throw new DemuxException("Invalid PMT: zero bit wasn't zero");
}
}
private void ReadTransportHeader(BitSplitter bs)
{
bs.SkipToNextByte(); // Sync byte
Error = bs.GetFlag();
StartIndicator = bs.GetFlag();
HighPriority = bs.GetFlag();
PID = (int)bs.GetInteger(13);
ScrambleCode = (int)bs.GetInteger(2);
HasAdaptionField = bs.GetFlag();
HasPayload = bs.GetFlag();
Counter = (int)bs.GetInteger(4);
}
private void CheckAdaptionField(BitSplitter bs)
{
if (HasAdaptionField)
{
int adaption_end = (int)bs.GetInteger(8);
adaption_end += bs.ByteOffset;
Discont = bs.GetFlag();
KeyFrame = bs.GetFlag();
ES_Prio = bs.GetFlag();
HasPCR = bs.GetFlag();
HasOPCR = bs.GetFlag();
HasSplice = bs.GetFlag();
PrivateFlag = bs.GetFlag();
AdapExtFlag = bs.GetFlag();
if (bs.BitOffset != 0)
{
throw new Exception("bit align problem");
}
if (HasPCR)
{
PCR = (long)bs.GetInteger(33);
bs.SkipBits(15); // throw away useless sync stuff.
}
if (HasOPCR)
{
bs.SkipBits(48); // throw away useless "old" timecode
}
if (HasSplice)
{
bs.SkipBits(8); // throw away splice counter
}
if (PrivateFlag)
{
int priv_len = (int)bs.GetInteger(8);
bs.SkipBytes(priv_len); // skip private data
}
// ignore the rest of the adaption field (it's mostly to support stuff we ignore)
int skip_len = adaption_end - bs.ByteOffset;
bs.SkipBytes(skip_len);
}
}
private int SectionNumber, LastSection; // should always be zero
/// <summary>
/// Digest a packet payload into structured table. Payload should be from the pointer field onward.
/// Does not yet handle multi-packet tables
/// </summary>
public PAT(byte[] RawPayload)
{
Map = new Dictionary <int, int>();
BitSplitter bs = new BitSplitter(RawPayload);
ValidateTable(bs);
bs.SkipBits(2); // reserved;
SectionLength = (int)bs.GetInteger(12);
TransportID = (int)bs.GetInteger(16);
bs.SkipBits(2); // reserved
Version = (int)bs.GetInteger(5);
IsCurrent = bs.GetFlag();
SectionNumber = (int)bs.GetInteger(8);
LastSection = (int)bs.GetInteger(8);
int bits_left = (SectionLength - 5) - 4; // remaining length in bytes, excluding CRC
int items = bits_left / 4;
for (int i = 0; i < items; i++)
{
int prog = (int)bs.GetInteger(16);
bs.SkipBits(3);
int pid = (int)bs.GetInteger(13);
if (!Map.ContainsKey(prog))
{
Map.Add(prog, pid);
}
else
{
throw new DemuxException("Invalid PAT: program number specified more than once (" + prog + ")");
}
}
// Ignoring CRC.
}
/// <summary>
/// Reads the long list of flags in the default PES header.
/// </summary>
private void ReadFlags(BitSplitter bs)
{
ScrambleControl = (int)bs.GetInteger(2);
HighPriority = bs.GetFlag();
HasAlignment = bs.GetFlag();
IsCopyright = bs.GetFlag();
IsOriginal = bs.GetFlag();
HasPTS = bs.GetFlag();
HasDTS = bs.GetFlag();
if (HasDTS && !HasPTS)
{
throw new DemuxException("Invalid PES: DTS without PTS is not allowed");
}
HasESCR = bs.GetFlag();
HasEsRate = bs.GetFlag();
UsesTrickMode = bs.GetFlag();
MoreCopyright = bs.GetFlag();
HasPesCRC = bs.GetFlag();
HasPesExtension = bs.GetFlag();
}
/// <summary>
/// Digest a packet payload into structured table. Payload should be from the pointer field onward.
/// Does not yet handle multi-packet tables
/// </summary>
public PMT(byte[] RawPayload)
{
BitSplitter bs = new BitSplitter(RawPayload);
Map = new Dictionary <int, int>();
ReverseMap = new Dictionary <StreamType, int>();
ValidateTable(bs);
bs.SkipBits(2);
SectionLength = (int)bs.GetInteger(12); // total length after this, in bytes; includes 4 byte CRC.
ProgramNumber = (int)bs.GetInteger(16);
bs.SkipBits(2);
Version = (int)bs.GetInteger(5);
IsCurrent = bs.GetFlag();
SectionNumber = (int)bs.GetInteger(8);
LastSection = (int)bs.GetInteger(8);
bs.SkipBits(3);
PCR_PID = (int)bs.GetInteger(13); // Either the PID of a channel timecode stream, or 0x1FFF for none.
bs.SkipBits(4);
ProgInfoLength = (int)bs.GetInteger(12); // number of bytes of descriptors.
if (bs.BitOffset != 0)
{
throw new DemuxException("Byte alignment error (internal)");
}
bs.SkipBytes(ProgInfoLength); // ignore descriptors.
int info_bytes = (SectionLength - ProgInfoLength) - 13; // bytes of descriptor.
while (info_bytes > 0) // descriptions can be variable length
{
int stream_type = (int)bs.GetInteger(8);
bs.SkipBits(3);
int pid = (int)bs.GetInteger(13);
bs.SkipBits(4);
if (!Map.ContainsKey(pid))
{
Map.Add(pid, stream_type); // more complete map of pid types
}
else
{
throw new DemuxException("Invalid PMT: PID specified more than once");
}
StreamType st = DecodeStreamType(stream_type);
if (!ReverseMap.ContainsKey(st))
{
ReverseMap.Add(st, pid); // store first pid of each type
}
int es_info_length = (int)bs.GetInteger(12);
bs.SkipBytes(es_info_length);
info_bytes -= 5 + es_info_length;
}
if (bs.BitOffset != 0)
{
throw new DemuxException("Invalid PMT: program info length didn't match data");
}
// ignoring CRC.
}