vdr-plugin-streamdev/remux/tsremux.c

#include "remux/tsremux.h"

#define SC_PICTURE  0x00  // "picture header"
#define PID_MASK_HI 0x1F
#define VIDEO_STREAM_S   0xE0

using namespace Streamdev;

void cTSRemux::SetBrokenLink(uchar *Data, int Length)
{
  int PesPayloadOffset = 0;
  if (AnalyzePesHeader(Data, Length, PesPayloadOffset) >= phMPEG1 && (Data[3] & 0xF0) == VIDEO_STREAM_S) {
     for (int i = PesPayloadOffset; i < Length - 7; i++) {
         if (Data[i] == 0 && Data[i + 1] == 0 && Data[i + 2] == 1 && Data[i + 3] == 0xB8) {
            if (!(Data[i + 7] & 0x40)) // set flag only if GOP is not closed
               Data[i + 7] |= 0x20;
            return;
            }
         }
     dsyslog("SetBrokenLink: no GOP header found in video packet");
     }
  else
     dsyslog("SetBrokenLink: no video packet in frame");
}

int cTSRemux::GetPid(const uchar *Data)
{
  return (((uint16_t)Data[0] & PID_MASK_HI) << 8) | (Data[1] & 0xFF);
}

int cTSRemux::GetPacketLength(const uchar *Data, int Count, int Offset)
{
  // Returns the length of the packet starting at Offset, or -1 if Count is
  // too small to contain the entire packet.
  int Length = (Offset + 5 < Count) ? (Data[Offset + 4] << 8) + Data[Offset + 5] + 6 : -1;
  if (Length > 0 && Offset + Length <= Count)
     return Length;
  return -1;
}

int cTSRemux::ScanVideoPacket(const uchar *Data, int Count, int Offset, uchar &PictureType)
{
  // Scans the video packet starting at Offset and returns its length.
  // If the return value is -1 the packet was not completely in the buffer.
  int Length = GetPacketLength(Data, Count, Offset);
  if (Length > 0) {
     int PesPayloadOffset = 0;
     if (AnalyzePesHeader(Data + Offset, Length, PesPayloadOffset) >= phMPEG1) {
        const uchar *p = Data + Offset + PesPayloadOffset + 2;
        const uchar *pLimit = Data + Offset + Length - 3;
#ifdef TEST_cVideoRepacker
        // cVideoRepacker ensures that a new PES packet is started for a new sequence,
        // group or picture which allows us to easily skip scanning through a huge
        // amount of video data.
        if (p < pLimit) {
           if (p[-2] || p[-1] || p[0] != 0x01)
              pLimit = 0; // skip scanning: packet doesn't start with 0x000001
           else {
              switch (p[1]) {
                case SC_SEQUENCE:
                case SC_GROUP:
                case SC_PICTURE:
                     break;
                default: // skip scanning: packet doesn't start a new sequence, group or picture
                     pLimit = 0;
                }
              }
           }
#endif
        while (p < pLimit && (p = (const uchar *)memchr(p, 0x01, pLimit - p))) {
              if (!p[-2] && !p[-1]) { // found 0x000001
                 switch (p[1]) {
                   case SC_PICTURE: PictureType = (p[3] >> 3) & 0x07;
                                    return Length;
                   }
                 p += 4; // continue scanning after 0x01ssxxyy
                 }
              else
                 p += 3; // continue scanning after 0x01xxyy
              }
        }
     PictureType = NO_PICTURE;
     return Length;
     }
  return -1;
}