slice.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

//!      dummy encoding processes (for the R-D based selection), but that they are never
//!      reset, once the selection is made.  I believe that this breaks the MB-adaptive
//!      frame/field coding.  The necessary code for the state saves is readily available
//!      in macroblock.c, start_macroblock() and terminate_macroblock() (this code needs
//!      to be double checked that it works with CA-VLC as well
//!   2. would it be an option to allocate Bitstreams with zero data in them (or copy the
//!      already generated bitstream) for the "test coding"?  


          // code MB pair as frame MB 
          recode_macroblock = FALSE;
          img->field_mode = 0;  // MB coded as frame
          img->top_field = 0;   // Set top field to 0

          set_MB_parameters (CurrentMbInScanOrder);
          start_macroblock ();
//          img->update_stats = 0;        // don't update any stats yet                 //! This variable seems never be used
          
          SetStateVariablesForFrameMode();
          rdopt = &rddata_top_frame_mb; // store data in top frame MB 
          TopFrameIsSkipped = 0;
          WriteFrameFieldMBInHeader = 1;
          encode_one_macroblock ();     // code the MB as frame
          field_mb[img->mb_y][img->mb_x] = 0;   // set the MB as field (for use in FindSkipMotionVector)
          FrameRDCost = rdopt->min_rdcost;
          //***   Top MB coded as frame MB ***//

          // go to the bottom MB in the MB pair
          CurrentMbInScanOrder = img->current_mb_nr + MBRowSize;
          img->field_mode = 0;  // MB coded as frame  //GB
          set_MB_parameters (CurrentMbInScanOrder);
          start_macroblock ();
//          img->update_stats = 0;        // don't update any stats yet                 //! This variable seems never be used
          rdopt = &rddata_bot_frame_mb; // store data in top frame MB
          WriteFrameFieldMBInHeader = TopFrameIsSkipped ? 1 : 0;
          field_mb[img->mb_y][img->mb_x] = 0;
          encode_one_macroblock ();     // code the MB as frame
          field_mb[img->mb_y][img->mb_x] = 0;   // set the MB as field (for use in FindSkipMotionVector)
          FrameRDCost += rdopt->min_rdcost;

          //***   Bottom MB coded as frame MB ***//


          // start coding the MB pair as a field MB pair
          CurrentMbInScanOrder -= MBRowSize;                //! FMO problem and generally dirty, just to go back like this
          img->field_mode = 1;  // MB coded as frame
          img->top_field = 1;   // Set top field to 1
          set_MB_parameters (CurrentMbInScanOrder);
          img->buf_cycle <<= 1;
          input->no_multpred <<= 1;
          img->num_ref_pic_active_fwd_minus1 <<= 1;
          img->num_ref_pic_active_fwd_minus1 += 1;
          start_macroblock ();



          img->height = input->img_height >> 1; 
          rdopt = &rddata_top_field_mb; // store data in top frame MB 
          SetStateVariablesForFieldMode();
          TopFieldIsSkipped = 0;        // set the top field MB skipped flag to 0
          WriteFrameFieldMBInHeader = 1;
          encode_one_macroblock ();     // code the MB as frame
          field_mb[img->mb_y][img->mb_x] = 1;   // set the MB as field (for use in FindSkipMotionVector)
          FieldRDCost = rdopt->min_rdcost;
          //***   Top MB coded as field MB ***//

          CurrentMbInScanOrder += MBRowSize;
          img->top_field = 0;   // Set top field to 0
          set_MB_parameters (CurrentMbInScanOrder);
          start_macroblock ();
          rdopt = &rddata_bot_field_mb; // store data in top frame MB 
          SetStateVariablesForFieldMode();
          WriteFrameFieldMBInHeader = TopFieldIsSkipped ? 1 : 0;
          encode_one_macroblock ();     // code the MB as frame
          field_mb[img->mb_y][img->mb_x] = 1;   // set the MB as field (for use in FindSkipMotionVector)
          FieldRDCost += rdopt->min_rdcost;
          //***   Bottom MB coded as field MB ***//

          // decide between frame/field MB pair
          if (FrameRDCost < FieldRDCost)
          {
            img->field_mode = 0;
            img->buf_cycle >>= 1;
            input->no_multpred >>= 1;
            MBPairIsField = 0;
            SetStateVariablesForFrameMode();
            img->num_ref_pic_active_fwd_minus1 -= 1;
            img->num_ref_pic_active_fwd_minus1 >>= 1;
            
          }
          else
          {
            img->field_mode = 1;
            MBPairIsField = 1;
            SetStateVariablesForFieldMode();
            img->height = input->img_height / 2;      // set image height as frame height
          }


          if (MBPairIsField)
            img->top_field = 1;
          else
            img->top_field = 0;

          // go back to the Top MB in the MB pair
          CurrentMbInScanOrder -= MBRowSize;
          set_MB_parameters (CurrentMbInScanOrder);
          start_macroblock ();
          for (i=0;i<4;i++)
            for (j=0;j<4;j++)
            {
              img->field_anchor[img->block_y+j][img->block_x+i] = img->field_mode;
            }
//          img->update_stats = 1;        // Now update the stats                 //! This variable seems never be used
          rdopt =  img->field_mode ? &rddata_top_field_mb : &rddata_top_frame_mb;
          copy_rdopt_data (0);  // copy the MB data for Top MB from the temp buffers
          WriteFrameFieldMBInHeader = 1;
          write_one_macroblock (1);     // write the Top MB data to the bitstream
          NumberOfCodedMBs++;   // only here we are sure that the coded MB is actually included in the slice
          terminate_macroblock (&end_of_slice, &recode_macroblock);     // done coding the Top MB 
          proceed2nextMacroblock (CurrentMbInScanOrder);        // Go to next macroblock

          // go to the Bottom MB in the MB pair
          CurrentMbInScanOrder += MBRowSize;
          img->top_field = 0;
          set_MB_parameters (CurrentMbInScanOrder);
          start_macroblock ();
          for (i=0;i<4;i++)
            for (j=0;j<4;j++)
            {
              img->field_anchor[img->block_y+j][img->block_x+i] = img->field_mode;
            }
//          img->update_stats = 1;        // Now update the stats                 //! This variable seems never be used
          rdopt = img->field_mode ? &rddata_bot_field_mb : &rddata_bot_frame_mb;
          copy_rdopt_data (1);  // copy the MB data for Bottom MB from the temp buffers
          if (img->field_mode)
            WriteFrameFieldMBInHeader = TopFieldIsSkipped ? 1 : 0;
          else
            WriteFrameFieldMBInHeader = TopFrameIsSkipped ? 1 : 0;

          write_one_macroblock (0);     // write the Bottom MB data to the bitstream
          NumberOfCodedMBs++;   // only here we are sure that the coded MB is actually included in the slice
          terminate_macroblock (&end_of_slice, &recode_macroblock);     // done coding the Top MB 
          proceed2nextMacroblock (CurrentMbInScanOrder);        // Go to next macroblock

          CurrentMbInScanOrder -= MBRowSize;

          if (MBPairIsField)    // if MB Pair was coded as field the buffer size variables back to frame mode
          {
            img->buf_cycle >>= 1;
            input->no_multpred >>= 1;
            img->num_ref_pic_active_fwd_minus1 -= 1;
            img->num_ref_pic_active_fwd_minus1 >>= 1;
          }
          img->field_mode = img->top_field = 0; // reset to frame mode
          img->height = input->img_height;      // reset the img->height  

          CurrentMbInScanOrder++;     //! Breaks FMO
          if (CurrentMbInScanOrder == img->total_number_mb - MBRowSize)
            end_of_slice = TRUE;        // just in case it does n't get set in terminate_macroblock

          if (CurrentMbInScanOrder % MBRowSize == 0)    //! Breaks FMO
            CurrentMbInScanOrder += MBRowSize;
        }

    }
/*
  // Tian Dong: June 7, 2002 JVT-B042
  // Restore the short_used
  if (input->NumFramesInELSubSeq)
    {
      fb->short_used = short_used;
      img->nb_references = img_ref;
    }
*/
  terminate_slice ();
  return NumberOfCodedMBs;
}



/*!
 ************************************************************************
 * \brief
 *    Initializes the parameters for a new slice and
 *     allocates the memory for the coded slice in the Picture structure
 *  \par Side effects:
 *      Adds slice/partition header symbols to the symbol buffer
 *      increments Picture->no_slices, allocates memory for the
 *      slice, sets img->currSlice
 ************************************************************************
 */
static void init_slice ()
{
  int i;
  Picture *currPic = img->currentPicture;
  Slice *curr_slice;
  DataPartition *dataPart;
  Bitstream *currStream;

  // Allocate new Slice in the current Picture, and set img->currentSlice
  assert (currPic != NULL);
  currPic->no_slices++;
  if (currPic->no_slices >= MAXSLICEPERPICTURE)
    error ("Too many slices per picture, incease MAXLSICESPERPICTURE in global.h, exitus", -1);
  currPic->slices[currPic->no_slices-1] = malloc_slice();
  curr_slice = currPic->slices[currPic->no_slices-1];
  img->currentSlice = curr_slice;

  curr_slice->picture_id = img->tr % 256;
  curr_slice->qp = img->qp;
  curr_slice->start_mb_nr = img->current_mb_nr;
  curr_slice->slice_too_big = dummy_slice_too_big;

  for (i = 0; i < curr_slice->max_part_nr; i++)
  {
    dataPart = &(curr_slice->partArr[i]);
    if (input->symbol_mode == UVLC)
      dataPart->writeSyntaxElement = writeSyntaxElement_UVLC;
    else
      dataPart->writeSyntaxElement = writeSyntaxElement_CABAC;
    
    currStream = dataPart->bitstream;
    currStream->bits_to_go = 8;
    currStream->byte_pos = 0;
    currStream->byte_buf = 0;
  }
}


/*!
 ************************************************************************
 * \brief
 *    Allocates a slice structure along with its dependentdata structures
 * \return
 *    Pointer to a Slice
 ************************************************************************
 */
static Slice *malloc_slice()
{
  int i;
  DataPartition *dataPart;
  Slice *slice;
  const int buffer_size = (img->width * img->height * 4); // AH 190202: There can be data expansion with 
                                                          // low QP values. So, we make sure that buffer 
                                                          // does not everflow. 4 is probably safe multiplier.

  if ((slice = (Slice *) calloc(1, sizeof(Slice))) == NULL) no_mem_exit ("malloc_slie: slice structure");

  if (input->symbol_mode == CABAC)
    {
      // create all context models
      slice->mot_ctx = create_contexts_MotionInfo();
      slice->tex_ctx = create_contexts_TextureInfo();
    }

  slice->max_part_nr = input->partition_mode==0?1:3;

  slice->num_mb = 0;          // no coded MBs so far

  if ((slice->partArr = (DataPartition *) calloc(slice->max_part_nr, sizeof(DataPartition))) == NULL) no_mem_exit ("malloc_slice: partArr");
  for (i=0; i<slice->max_part_nr; i++) // loop over all data partitions
  {
    dataPart = &(slice->partArr[i]);
    if ((dataPart->bitstream = (Bitstream *) calloc(1, sizeof(Bitstream))) == NULL) no_mem_exit ("malloc_slice: Bitstream");
    if ((dataPart->bitstream->streamBuffer = (byte *) calloc(buffer_size, sizeof(byte))) == NULL) no_mem_exit ("malloc_slice: StreamBuffer");
    // Initialize storage of bitstream parameters
  }
  return slice;
}


/*!
 ************************************************************************
 * \brief
 *    Memory frees of all Slice structures and of its dependent
 *    data structures
 * \par Input:
 *    Image Parameters struct struct img_par *img
 ************************************************************************
 */
void free_slice_list(Picture *currPic)
{
  int i;

  for (i=0; i<currPic->no_slices; i++)
  {
    free_slice (currPic->slices[i]);
    currPic->slices[i]=NULL;
  }
}


/*!
 ************************************************************************
 * \brief
 *    Memory frees of the Slice structure and of its dependent
 *    data structures
 * \para slice:
 *    Slice to be freed
 ************************************************************************
 */
static void free_slice(Slice *slice)
{
  int i;
  DataPartition *dataPart;

  if (slice != NULL)
  {
    for (i=0; i<slice->max_part_nr; i++) // loop over all data partitions
    {
      dataPart = &(slice->partArr[i]);
      if (dataPart != NULL)
      {
        if (dataPart->bitstream->streamBuffer != NULL)
          free(dataPart->bitstream->streamBuffer);
        if (dataPart->bitstream != NULL)
          free(dataPart->bitstream);
      }
    }
    if (slice->partArr != NULL)
      free(slice->partArr);
    if (input->symbol_mode == CABAC)
    {
      delete_contexts_MotionInfo(slice->mot_ctx);
      delete_contexts_TextureInfo(slice->tex_ctx);
    }
    //free(img->currentSlice);
    free(slice);
  }
}


/*!
 ************************************************************************
 * \brief
 *    This function set the value of a bit in a bitstream to 1
 ************************************************************************
 */
void modify_redundant_pic_cnt(unsigned char *buffer)
{
  unsigned char tmp = 1 << (rpc_bits_to_go-1);
  buffer[rpc_bytes_to_go] |= tmp;
}