rtp.c

包含了从MPEG4的视频解码到H.264的视频编码部分的源代码

    }
  }
  else
  {
    if (img->structure == FRAME)
    {     
      if(img->tr <last_imgtr_frm_b) 
        modulo_ctr_frm_b++;
      
      last_imgtr_frm_b = img->tr;
      img->tr_frm = img->tr + (256*modulo_ctr_frm_b);
    }
    else
    {
      if(img->tr <last_imgtr_fld_b) 
        modulo_ctr_fld_b++;
      
      last_imgtr_fld_b = img->tr;
      img->tr_fld = img->tr + (256*modulo_ctr_fld_b);
    }
  }
  if(img->type == img->type==B_IMG) 
  {
    img->direct_type=sh->Direct_type;
  }
  if(img->type != B_IMG) {
    img->pstruct_next_P = img->structure;
    if(img->structure == TOP_FIELD)
    {
      img->imgtr_last_P = img->imgtr_next_P;
      img->imgtr_next_P = img->tr_fld;
    }
    else if(img->structure == FRAME)
    {
      img->imgtr_last_P = img->imgtr_next_P;
      img->imgtr_next_P = 2*img->tr_frm;
    }
  }
  
  if(img->type==B_IMG)
  {
    if(img->disposable_flag==0) {
        if(img->structure == TOP_FIELD)
        {
          img->imgtr_last_P = img->imgtr_next_P;
          img->imgtr_next_P = img->tr_fld;
        }
        else if(img->structure == FRAME)
        {
          img->imgtr_last_P = img->imgtr_next_P;
          img->imgtr_next_P = 2*img->tr_frm;
        }
      }
  }

  img->slice_group_change_cycle = sh->slice_group_change_cycle; //JVT-D097
}


/*!
 *****************************************************************************
 *
 * \brief 
 *    Function returns the next header type (SOS SOP, EOS)
 *    p-> and sh-> are filled.  p-> does not need memory for payload and packet
 *
 * \return
 *
 * Side effects:
 *
 * \date
 *    27 October, 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/



int RTPGetFollowingSliceHeader (struct img_par *img, RTPpacket_t *p, RTPSliceHeader_t *sh)
{
  long int Filepos;
  int TotalPackLen;
  int done=0;
  int intime=0;
  Slice *currSlice = img->currentSlice;
//  static unsigned int old_seq=0; // avoid warnings. mwi
//  static int first=0; // avoid warnings. mwi
//  static int i=2; // avoid warnings. mwi
  
  RTPpacket_t *newp, *nextp;
  RTPSliceHeader_t *nextsh;
  
  assert (p != NULL);
  assert (sh != NULL);

  newp = alloca (sizeof (RTPpacket_t));
  newp->packet = alloca (MAXRTPPACKETSIZE);
  newp->payload = alloca(MAXRTPPAYLOADLEN);
  nextp=alloca (sizeof (RTPpacket_t));
  nextsh=alloca(sizeof (RTPSliceHeader_t));

  Filepos = ftell (bits);

  while (!done)
  {
    if (4 != fread (&TotalPackLen,1, 4, bits))
    {
      fseek (bits, Filepos, SEEK_SET);
      return EOS;    // EOF inidication
    }
    
    if (4 != fread (&intime, 1, 4, bits))
    {
      fseek (bits, Filepos, SEEK_SET);
      printf ("RTPGetFollowingSliceHeader: File corruption, could not read Timestamp\n");
      return EOS;
    }

    newp->packlen = TotalPackLen;
    assert (newp->packlen < MAXRTPPACKETSIZE);
    if (newp->packlen != fread (newp->packet, 1, newp->packlen, bits))
    {
      fseek (bits, Filepos, SEEK_SET);
      return EOS;    // EOF inidication
    }
    DecomposeRTPpacket (newp);
    if (newp->payload [0] == 0 || newp->payload[0] == 1)   // Full Slice or Partition A
      done = 1;
  }
  fseek (bits, Filepos, SEEK_SET);
  p->cc = newp->cc;
  p->m = newp->m;
  p->p = newp->p;
  p->pt = newp->pt;
  p->seq = newp->seq;
  p->ssrc = newp->ssrc;
  p->timestamp = newp->timestamp;
  p->v = newp->v;
  p->x = newp->x;

  //! This code fragment made the assumtion of a fixed frame rate with no fixed frames
  //! It is commented out, because I believe that such an assumption is unrealistic in
  //! real world environments, and the resulting gains in error concealment quality
  //! should not be part of the reference code.  I don't believe it does do much harm
  //! to keep it from a functional point-of-view.  StW, 06.07.02

/*
  if (p->seq != old_seq+i)
    currSlice->next_eiflag =1;
  else
  {
    currSlice->next_eiflag =0;
    old_seq=p->seq;
  }

  if(!first)
  {
    first=1;
    i=1;
  }
*/  
  RTPInterpretSliceHeader (&newp->payload[1], newp->packlen, newp->payload[0]==0?0:1, sh, img);
  if(currSlice->picture_id != sh->PictureID) 
    return (SOP);
  else
    return (SOS);
}
  
/*!
 ************************************************************************
 * \brief
 *    Input file containing Partition structures
 * \return
 *    TRUE if a startcode follows (meaning that all symbols are used).  \n
 *    FALSE otherwise.
 ************************************************************************/
int RTP_startcode_follows(struct img_par *img, struct inp_par *inp)
{
  Slice *currSlice = img->currentSlice;
  int dp_Nr = assignSE2partition[currSlice->dp_mode][SE_MBTYPE];
  DataPartition *dP = &(currSlice->partArr[dp_Nr]);
  Bitstream   *currStream = dP->bitstream;
  byte *buf = currStream->streamBuffer;
  int frame_bitoffset = currStream->frame_bitoffset;
  int info;

  assert (0==1);
//  if (currStream->ei_flag)
//  {
    //printf ("ei_flag set, img->current_mb_nr %d, currSlice->last_mb_nr %d\n", img->current_mb_nr, currSlice->last_mb_nr);
//    return (img->current_mb_nr == currSlice->last_mb_nr);
//  }
//  else
  {
    if (-1 == GetVLCSymbol (buf, frame_bitoffset, &info, currStream->bitstream_length))
      return TRUE;
    else
      return FALSE;
  }
}


/*!
 ************************************************************************
 * \brief
 *    read next UVLC codeword from SLICE-partition and
 *    map the corresponding syntax element
 *     Add Errorconceilment if necessary
 ************************************************************************
 */
int readSyntaxElement_RTP(SyntaxElement *sym, struct img_par *img, struct inp_par *inp, struct datapartition *dP)
{
  Bitstream   *currStream = dP->bitstream;

  if (RTP_symbols_available(currStream))    // check on existing elements in partition
  {
    RTP_get_symbol(img, inp, dP, sym, currStream);
  }
  else
  {
    set_ec_flag(sym->type);           // otherwise set error concealment flag
  }
  get_concealed_element(sym);

  sym->mapping(sym->len,sym->inf,&(sym->value1),&(sym->value2));

#if TRACE
  tracebits(sym->tracestring, sym->len, sym->inf, sym->value1, sym->value2);
#endif

  return 1;
}

/*!
 ************************************************************************
 * \brief
 *    checks if thererare symbols to read in the
 *    appropriate partition
 ************************************************************************
 */
int RTP_symbols_available (Bitstream *currStream)
{
  byte *buf = currStream->streamBuffer;
  int frame_bitoffset = currStream->frame_bitoffset;
  int info;

  if (currStream->ei_flag) {
    //printf ("RTP_symbols_available returns FALSE: ei_flag set\n");
    return FALSE;
  }
  if (-1 == GetVLCSymbol (buf, frame_bitoffset, &info, currStream->bitstream_length))
  {
    //printf ("RTP_symbols_available returns FALSE, no more symbols\nframe_bitoffset %d, bitstream_length %d read_len %d\n", currStream->frame_bitoffset, currStream->bitstream_length, currStream->read_len);
    return FALSE;
  }
  else
    return TRUE;
};

/*!
 ************************************************************************
 * \brief
 *    gets info and len of symbol
 ************************************************************************
 */
void RTP_get_symbol(struct img_par *img, struct inp_par *inp, struct datapartition *dP, SyntaxElement *sym, Bitstream *currStream)
{
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  sym->len =  GetVLCSymbol (buf, frame_bitoffset, &(sym->inf), BitstreamLengthInBytes);
  currStream->frame_bitoffset += sym->len;
}



/*!
 ************************************************************************
 * \brief
 *    Interprets a parameter set packet
 ************************************************************************
 */

#define EXPECT_ATTR 0
#define EXPECT_PARSET_LIST 1
#define EXPECT_PARSET_NO 2
#define EXPECT_STRUCTNAME 3
#define EXPECT_STRUCTVAL_INT 4
#define EXPECT_STRUCTVAL_STRING 5
#define EXPECT_STRUCTVAL_INT_LIST 6

#define INTERPRET_COPY 100
#define INTERPRET_ENTROPY_CODING 101
#define INTERPRET_MOTION_RESOLUTION 102
#define INTERPRET_INTRA_PREDICTION 103
#define INTERPRET_PARTITIONING_TYPE 104
#define INTERPRET_FMOMAP 105

int RTPInterpretParameterSetPacket (char *buf, int buflen)

{
  // The dumbest possible parser that updates the parameter set variables 
  // static to this module

  int bufp = 0;
  int state = EXPECT_ATTR;
  int interpreter;
  int minus, number;
  int ps;
  char s[MAX_PARAMETER_STRINGLEN];
  void *destin;

  while (bufp < buflen)
  {
// printf ("%d\t%d\t %c%c%c%c%c%c%c%c  ", bufp, state, buf[bufp], buf[bufp+1], buf[bufp+2], buf[bufp+3], buf[bufp+4], buf[bufp+5], buf[bufp+6], buf[bufp+7], buf[bufp+8], buf[bufp+9]);

    switch (state)
    {
    case EXPECT_ATTR:
      if (buf[bufp] == '\004')      // Found UNIX EOF, this is the end marker
      {
        ParSet[ps].Valid = 1;
        return 0;
      }
      if (strncmp ("a=H26L ", &buf[bufp], 7))
      {
        printf ("Parsing error EXPECT_ATTR in Header Packet: position %d, packet %s\n",
                 bufp, &buf[bufp]);
        return -1;
      }
      bufp += 7;
      state = EXPECT_PARSET_LIST;
      break;

    case EXPECT_PARSET_LIST:
      if (buf[bufp] != '(')
      {
        printf ("Parsing error EXPECT_PARSET in Header Packet: position %d, packet %s\n",
                bufp, &buf[bufp]);
        return -2;
      }
      bufp++;
      state = EXPECT_PARSET_NO;
      break;

    case EXPECT_PARSET_NO:
      number = 0;
      minus = 1;
      if (buf[bufp] == '-')
      {
        minus = -1;
        bufp++;
      }
      while (isdigit (buf[bufp]))
        number = number * 10 + ( (int)buf[bufp++] - (int) '0');
      if (buf[bufp] == ',')
      {
        printf ("Update of more than one prameter set not yet supported\n");
        return -1;
      }
      if (buf[bufp] != ')')
      {
        printf ("Parsing error NO PARSET LISTEND in Header Packet: position %d, packet %s\n",
          bufp, &buf[bufp]);
        return -1;
      }
      if (minus > 0)      // not negative
        ps = number;

      bufp+= 2;     // skip ) and blank
      state = EXPECT_STRUCTNAME;
      break;

    case EXPECT_STRUCTNAME:
      if (1 != sscanf (&buf[bufp], "%100s", s))   // Note the 100, which si MAX_PARAMETER_STRLEN
      {
        printf ("Parsing error EXPECT STRUCTNAME STRING in Header packet: position %d, packet %s\n",
               bufp, &buf[bufp]);
        return -1;
      }
      bufp += strlen (s);
      bufp++;       // Skip the blank


      if (!strncmp (s, "MaxPicID", MAX_PARAMETER_STRINGLEN))
      {
        state = EXPECT_STRUCTVAL_INT;
        interpreter = INTERPRET_COPY;
        destin = &ParSet[ps].MaxPicID;
        break;
      }
      if (!strncmp (s, "BufCycle", MAX_PARAMETER_STRINGLEN))
      {
        state = EXPECT_STRUCTVAL_INT;
        interpreter = INTERPRET_COPY;
        destin = &ParSet[ps].BufCycle;
        break;
      }
      if (!strncmp (s, "MaxPn", MAX_PARAMETER_STRINGLEN))
      {
        state = EXPECT_STRUCTVAL_INT;
        interpreter = INTERPRET_COPY;
        destin = &ParSet[ps].BufCycle;
        break;
      }

      if (!strncmp (s, "UseMultpred", MAX_PARAMETER_STRINGLEN))
      {
        state = EXPECT_STRUCTVAL_INT;
        interpreter = INTERPRET_COPY;
        destin = &ParSet[ps].UseMultpred;
        break;
      }

      if (!strncmp (s, "PixAspectRatioX", MAX_PARAMETER_STRINGLEN))
      {
        state = EXPECT_STRUCTVAL_INT;
        interpreter = INTERPRET_COPY;