video.cpp

This code is based on mpeg_play, available from: http://bmrc.berkeley.edu/frame/research/mpeg/

  vid_stream->mb_width = (vid_stream->h_size + 15) / 16;
  vid_stream->mb_height = (vid_stream->v_size + 15) / 16;

#ifndef DISABLE_DITHER
  /* If dither type is MBORDERED allocate ditherFlags. */
  if (ditherType == MBORDERED_DITHER) {
    vid_stream->ditherFlags =
         (char *) malloc(vid_stream->mb_width*vid_stream->mb_height);
  }
#endif

  /* Parse of aspect ratio code. */

  get_bits4(data);
  vid_stream->aspect_ratio = (unsigned char) data;

  /* Parse off picture rate code. */

  get_bits4(data);
  vid_stream->picture_rate = (unsigned char) data;

  /* Parse off bit rate. */

  get_bits18(data);
  vid_stream->bit_rate = data;

  /* Flush marker bit. */

  flush_bits(1);

  /* Parse off vbv buffer size. */

  get_bits10(data);
  vid_stream->vbv_buffer_size = data;

#ifdef not_def
  /* Lets not bother with this.  Only increases memory image */
  if (data*1024>vid_stream->max_buf_length) {
    unsigned int *newbuf;
    int sz=1024*data+1;
    /* If they actually want a bigger buffer than we default to,
       let them have it! (if we can) */
    newbuf = (unsigned int *) realloc(vid_stream->buf_start, (unsigned int) 4*sz);
    if (newbuf!=(unsigned int *)NULL) {
      vid_stream->max_buf_length=sz;
      vid_stream->buffer=
          (vid_stream->buffer-vid_stream->buf_start)+newbuf;
      vid_stream->buf_start=newbuf;
    }}
#endif

  /* Parse off contrained parameter flag. */

  get_bits1(data);
  if (data) {
    vid_stream->const_param_flag = TRUE;
  } else
    vid_stream->const_param_flag = FALSE;

  /*
   * If intra_quant_matrix_flag set, parse off intra quant matrix values.
   */

  get_bits1(data);
  if (data) {
    for (i = 0; i < 64; i++) {
      get_bits8(data);

      vid_stream->intra_quant_matrix[zigzag[i][1]][zigzag[i][0]] =
        (unsigned char) data;
    }
  }
  /*
   * If non intra quant matrix flag set, parse off non intra quant matrix
   * values.
   */

  get_bits1(data);
  if (data) {
    for (i = 0; i < 64; i++) {
      get_bits8(data);

      vid_stream->non_intra_quant_matrix[zigzag[i][1]][zigzag[i][0]] =
        (unsigned char) data;
    }
  }

  /* Adjust noise base matrix according to non_intra matrix */
  for( i = 0; i < 8; i++ )
    for( j = 0; j < 8; j++ )
      vid_stream->noise_base_matrix[i][j] = (short) vid_stream->non_intra_quant_matrix[i][j];
  
  j_rev_dct((short *) vid_stream->noise_base_matrix);
  
  for( i = 0; i < 8; i++ )
    for( j = 0; j < 8; j++ )
      vid_stream->noise_base_matrix[i][j] *= vid_stream->noise_base_matrix[i][j];

  /* Go to next start code. */

  next_start_code(vid_stream);

  /*
   * If next start code is extension start code, parse off extension data.
   */

  if (next_bits(32, EXT_START_CODE, vid_stream)) {
    flush_bits32;
    if (vid_stream->ext_data != NULL) {
      free(vid_stream->ext_data);
      vid_stream->ext_data = NULL;
    }
    vid_stream->ext_data = get_ext_data(vid_stream);
  }
  /* If next start code is user start code, parse off user data. */

  if (next_bits(32, USER_START_CODE, vid_stream)) {
    flush_bits32;
    if (vid_stream->user_data != NULL) {
      free(vid_stream->user_data);
      vid_stream->user_data = NULL;
    }
    vid_stream->user_data = get_ext_data(vid_stream);
  }
  return PARSE_OK;
}


/*
 *--------------------------------------------------------------
 *
 * ParseGOP --
 *
 *      Parses of group of pictures header from bit stream
 *      associated with vid_stream.
 *
 * Results:
 *      Values in gop header placed into video stream structure.
 *
 * Side effects:
 *      Bit stream irreversibly parsed.
 *
 *--------------------------------------------------------------
 */

static int ParseGOP( VidStream* vid_stream )
{
  unsigned int data;

  /* Flush group of pictures start code. */

  flush_bits32;

  /* Parse off drop frame flag. */

  get_bits1(data);
  if (data) {
    vid_stream->group.drop_flag = TRUE;
  } else
    vid_stream->group.drop_flag = FALSE;

  /* Parse off hour component of time code. */

  get_bits5(data);
  vid_stream->group.tc_hours = data;

  /* Parse off minute component of time code. */

  get_bits6(data);
  vid_stream->group.tc_minutes = data;

  /* Flush marker bit. */

  flush_bits(1);

  /* Parse off second component of time code. */

  get_bits6(data);
  vid_stream->group.tc_seconds = data;

  /* Parse off picture count component of time code. */

  get_bits6(data);
  vid_stream->group.tc_pictures = data;

  /* Parse off closed gop and broken link flags. */

  get_bits2(data);
  if (data > 1) {
    vid_stream->group.closed_gop = TRUE;
    if (data > 2) {
      vid_stream->group.broken_link = TRUE;
    } else
      vid_stream->group.broken_link = FALSE;
  } else {
    vid_stream->group.closed_gop = FALSE;
    if (data) {
      vid_stream->group.broken_link = TRUE;
    } else
      vid_stream->group.broken_link = FALSE;
  }

  /* Goto next start code. */

  next_start_code(vid_stream);

  /* If next start code is extension data, parse off extension data. */

  if (next_bits(32, EXT_START_CODE, vid_stream)) {
    flush_bits32;
    if (vid_stream->group.ext_data != NULL) {
      free(vid_stream->group.ext_data);
      vid_stream->group.ext_data = NULL;
    }
    vid_stream->group.ext_data = get_ext_data(vid_stream);
  }
  /* If next start code is user data, parse off user data. */

  if (next_bits(32, USER_START_CODE,vid_stream)) {
    flush_bits32;
    if (vid_stream->group.user_data != NULL) {
      free(vid_stream->group.user_data);
      vid_stream->group.user_data = NULL;
    }
    vid_stream->group.user_data = get_ext_data(vid_stream);
  }
  return PARSE_OK;
}


/*
 *--------------------------------------------------------------
 *
 * ParsePicture --
 *
 *      Parses picture header. Marks picture to be presented
 *      at particular time given a time stamp.
 *
 * Results:
 *      Values from picture header put into video stream structure.
 *
 * Side effects:
 *      Bit stream irreversibly parsed.
 *
 *--------------------------------------------------------------
 */

static int ParsePicture( VidStream* vid_stream, TimeStamp time_stamp )
{
  unsigned int data;
  int i;

  /* Flush header start code. */
  flush_bits32;

  /* This happens if there is a picture code before a sequence start */
  if (vid_stream->ring[0] == NULL) {
    printf("Warning: picture block before sequence header block\n");
    return SKIP_PICTURE;
  }

  /* Parse off temporal reference. */
  get_bits10(data);
  vid_stream->picture.temp_ref = data;

  /* Parse of picture type. */
  get_bits3(data);
  vid_stream->picture.code_type = data;

  if ((vid_stream->picture.code_type == B_TYPE) &&
      ((vid_stream->future == NULL) ||
       ((vid_stream->past == NULL) && !(vid_stream->group.closed_gop))))
    /* According to 2-D.5.1 (p D-18) this is ok, if the refereneces are OK */
    return SKIP_PICTURE;

  if ((vid_stream->picture.code_type == P_TYPE) && (vid_stream->future == NULL))
    return SKIP_PICTURE;

#ifdef ANALYSIS
  StartTime();
  stat_a[0].frametype = vid_stream->picture.code_type;
  stat_a[0].number = 1;
  stat_a[0].totsize = 45;
  pictureSizeCount = bitCountRead();
#endif

  /* Parse off vbv buffer delay value. */
  get_bits16(data);
  vid_stream->picture.vbv_delay = data;

  /* If P or B type frame... */

  if ((vid_stream->picture.code_type == P_TYPE) || 
      (vid_stream->picture.code_type == B_TYPE)) {

    /* Parse off forward vector full pixel flag. */
    get_bits1(data);
    if (data) {
      vid_stream->picture.full_pel_forw_vector = TRUE;
    } else {
      vid_stream->picture.full_pel_forw_vector = FALSE;
    }

    /* Parse of forw_r_code. */
    get_bits3(data);

    /* Decode forw_r_code into forw_r_size and forw_f. */

    vid_stream->picture.forw_r_size = data - 1;
    vid_stream->picture.forw_f = (1 << vid_stream->picture.forw_r_size);
  }
  /* If B type frame... */

  if (vid_stream->picture.code_type == B_TYPE) {

    /* Parse off back vector full pixel flag. */
    get_bits1(data);
    if (data)
      vid_stream->picture.full_pel_back_vector = TRUE;
    else
      vid_stream->picture.full_pel_back_vector = FALSE;

    /* Parse off back_r_code. */
    get_bits3(data);

    /* Decode back_r_code into back_r_size and back_f. */

    vid_stream->picture.back_r_size = data - 1;
    vid_stream->picture.back_f = (1 << vid_stream->picture.back_r_size);
  }
  /* Get extra bit picture info. */

  if (vid_stream->picture.extra_info != NULL) {
    free(vid_stream->picture.extra_info);
    vid_stream->picture.extra_info = NULL;
  }
  vid_stream->picture.extra_info = get_extra_bit_info(vid_stream);

  /* Goto next start code. */
  next_start_code(vid_stream);

  /* If start code is extension start code, parse off extension data. */

  if (next_bits(32, EXT_START_CODE, vid_stream)) {
    flush_bits32;

    if (vid_stream->picture.ext_data != NULL) {
      free(vid_stream->picture.ext_data);
      vid_stream->picture.ext_data = NULL;
    }
    vid_stream->picture.ext_data = get_ext_data(vid_stream);
  }
  /* If start code is user start code, parse off user data. */

  if (next_bits(32, USER_START_CODE, vid_stream)) {
    flush_bits32;

    if (vid_stream->picture.user_data != NULL) {
      free(vid_stream->picture.user_data);
      vid_stream->picture.user_data = NULL;
    }
    vid_stream->picture.user_data = get_ext_data(vid_stream);
  }

  /* Find a pict image structure in ring buffer not currently locked. */

  i = 0;

  while (vid_stream->ring[i]->locked != 0) {
    if (++i >= RING_BUF_SIZE) {
      perror("Fatal error. Ring buffer full.");
      exit(1);
    }
  }

  /* Set current pict image structure to the one just found in ring. */

  vid_stream->current = vid_stream->ring[i];

  /* Set time stamp. */

  vid_stream->current->show_time = time_stamp;

  /* Reset past macroblock address field. */

  vid_stream->mblock.past_mb_addr = -1;

#ifdef USE_ATI
  int back, forw, current;

  back = forw = -1;
  current = i;

  /* Look for indexes of future and past frames */
  for(i = 0; i < RING_BUF_SIZE; i++)
  {
    if(vid_stream->future == vid_stream->ring[i]) forw = i;
    if(vid_stream->past == vid_stream->ring[i]) back = i;
  }

  /* Start decoding a new frame */
  switch(vid_stream->picture.code_type)
  {
    case B_TYPE:
      vhar128_newdecode(vid_stream->ati_handle, forw, back, current);
    break;
    case P_TYPE:
      vhar128_newdecode(vid_stream->ati_handle, -1, forw, current);
    break;
    case I_TYPE:
      vhar128_newdecode(vid_stream->ati_handle, -1, -1, current);
    break;
  }
#endif

  return PARSE_OK;
}


/*
 *--------------------------------------------------------------
 *
 * ParseSlice --
 *
 *      Parses off slice header.
 *
 * Results:
 *      Values found in slice header put into video stream structure.
 *
 * Side effects:
 *      Bit stream irreversibly parsed.
 *
 *--------------------------------------------------------------
 */

static int ParseSlice( VidStream* vid_stream )
{
  unsigned int data;

  /* Flush slice start code. */

  flush_bits(24);

  /* Parse off slice vertical position. */

  get_bits8(data);
  vid_stream->slice.vert_pos = data;

  /* Parse off quantization scale. */

  get_bits5(data);
  vid_stream->slice.quant_scale = data;

  /* Parse off extra bit slice info. */

  if (vid_stream->slice.extra_info != NULL) {
    free(vid_stream->slice.extra_info);
    vid_stream->slice.extra_info = NULL;
  }