bitstream.cpp

gaca源码

            for(i = 1; i < 256; i++){
               tmp[i] = (bs->ShowBits(16) & 0xFF);

               if(tmp[i] == 0)
                  break;

               bs->Skip(8);
            }

            //DPRINTF(XVID_DEBUG_STARTCODE, "<user_data>: %s\n", tmp);

            /* read xvid bitstream version */
#ifdef WIN32
            {
               char packed;
               int version, build;
               if(MemCmp(tmp, "XviD", 4) == 0) {
                  sscanf(tmp, "XviD%d", &bs_version);
                  DPRINTF(XVID_DEBUG_HEADER, "xvid bitstream version=%i", bs_version);
               }

             /* divx detection */
               i = sscanf(tmp, "DivX%dBuild%d%c", &version, &build, &packed);
               if (i < 2)
                  i = sscanf(tmp, "DivX%db%d%c", &version, &build, &packed);
               if (i >= 2){
                  packed_mode = (i == 3 && packed == 'p');
                  //DPRINTF(XVID_DEBUG_HEADER, "divx version=%i, build=%i packed=%i\n", version, build, packed_mode);
               }
            }
#endif
         }
         break;
      default:
         switch(start_code & ~VIDOBJ_START_CODE_MASK){
         case VIDOBJ_START_CODE:
            {

               DPRINTF(XVID_DEBUG_STARTCODE, "<video_object>\n");
               DPRINTF(XVID_DEBUG_HEADER, "vo id %i\n", start_code & VIDOBJ_START_CODE_MASK);
                              //video_object_start_code
               bs->Skip(32);
            }
            break;
         case VIDOBJLAY_START_CODE:
            {

               DPRINTF(XVID_DEBUG_STARTCODE, "<video_object_layer>\n");
               DPRINTF(XVID_DEBUG_HEADER, "vol id %i\n", start_code & VIDOBJLAY_START_CODE_MASK);
               
               bs->Skip(32);  //video_object_layer_start_code
               bs->Skip(1);   //random_accessible_vol
               
               bs->Skip(8);   //video_object_type_indication
               
               if(bs->GetBit()){
                              //is_object_layer_identifier
                  DPRINTF(XVID_DEBUG_HEADER, "+ is_object_layer_identifier\n");
                  vol_ver_id = bs->GetBits(4);  /* video_object_layer_verid */
                  DPRINTF(XVID_DEBUG_HEADER,"ver_id %i\n", vol_ver_id);
                  bs->Skip(3);   /* video_object_layer_priority */
               }else{
                  vol_ver_id = 1;
               }
               
               aspect_ratio = bs->GetBits(4);
               
               if(aspect_ratio == VIDOBJLAY_AR_EXTPAR){
                              //aspect_ratio_info
                  DPRINTF(XVID_DEBUG_HEADER, "+ aspect_ratio_info\n");
                  par_width = bs->GetBits(8);   /* par_width */
                  par_height = bs->GetBits(8);  /* par_height */
               }
               
               if(bs->GetBit()){
                              //vol_control_parameters
                  DPRINTF(XVID_DEBUG_HEADER, "+ vol_control_parameters\n");
                  bs->Skip(2);   /* chroma_format */
                  low_delay = (bs->GetBit()!=0);
                  DPRINTF(XVID_DEBUG_HEADER, "low_delay %i\n", (int)low_delay);
                  if (bs->GetBit()) /* vbv_parameters */
                  {
                     unsigned int bitrate;
                     unsigned int buffer_size;
                     unsigned int occupancy;
                     
                     DPRINTF(XVID_DEBUG_HEADER,"+ vbv_parameters\n");
                     
                     bitrate = bs->GetBits(15) << 15; /* first_half_bit_rate */
                     READ_MARKER();
                     bitrate |= bs->GetBits(15);      /* latter_half_bit_rate */
                     READ_MARKER();
                     
                     buffer_size = bs->GetBits(15) << 3; /* first_half_vbv_buffer_size */
                     READ_MARKER();
                     buffer_size |= bs->GetBits(3);      /* latter_half_vbv_buffer_size */
                     
                     occupancy = bs->GetBits(11) << 15;  /* first_half_vbv_occupancy */
                     READ_MARKER();
                     occupancy |= bs->GetBits(15); /* latter_half_vbv_occupancy */
                     READ_MARKER();
                     
                     DPRINTF(XVID_DEBUG_HEADER,"bitrate %d (unit=400 bps)\n", bitrate);
                     DPRINTF(XVID_DEBUG_HEADER,"buffer_size %d (unit=16384 bits)\n", buffer_size);
                     DPRINTF(XVID_DEBUG_HEADER,"occupancy %d (unit=64 bits)\n", occupancy);
                  }
               }else{
                  low_delay = low_delay_default;
               }
               
                              //video_object_layer_shape
               shape = bs->GetBits(2);
               
               DPRINTF(XVID_DEBUG_HEADER, "shape %i\n", shape);
               if(shape != VIDOBJLAY_SHAPE_RECTANGULAR){
                  DPRINTF(XVID_DEBUG_ERROR,"non-rectangular shapes are not supported\n");
               }
               
               if(shape == VIDOBJLAY_SHAPE_GRAYSCALE && vol_ver_id != 1){
                              //video_object_layer_shape_extension
                  bs->Skip(4);
               }
               
               READ_MARKER();
               
               /********************** for decode B-frame time ***********************/
               time_inc_resolution = bs->GetBits(16); /* vop_time_increment_resolution */
               DPRINTF(XVID_DEBUG_HEADER,"vop_time_increment_resolution %i\n", time_inc_resolution);
               
#if 0
               time_inc_resolution--;
#endif
               
               if(time_inc_resolution > 0){
                  time_inc_bits = log2bin(time_inc_resolution-1);
               }else{
#if 0
                  time_inc_bits = 0;
#endif
                  /* for "old" xvid compatibility, set time_inc_bits = 1 */
                  time_inc_bits = 1;
               }
               
               READ_MARKER();
               
               if(bs->GetBit()){
                              //fixed_vop_rate
                  DPRINTF(XVID_DEBUG_HEADER, "+ fixed_vop_rate\n");
                  bs->Skip(time_inc_bits);   //fixed_vop_time_increment
               }
               
               if(shape != VIDOBJLAY_SHAPE_BINARY_ONLY){
                  
                  if(shape == VIDOBJLAY_SHAPE_RECTANGULAR){
                     dword _width, _height;
                     
                     READ_MARKER();
                     _width = bs->GetBits(13);  //video_object_layer_width
                     READ_MARKER();
                     _height = bs->GetBits(13); //video_object_layer_height
                     READ_MARKER();
                     
                     DPRINTF(XVID_DEBUG_HEADER, "width %i\n", _width);
                     DPRINTF(XVID_DEBUG_HEADER, "height %i\n", _height);
                     
                     if(width != _width || height != _height){
                        if(fixed_dimensions){
                           DPRINTF(XVID_DEBUG_ERROR, "decoder width/height does not match bitstream\n");
                           return -1;
                        }
                        resize = 1;
                        width = _width;
                        height = _height;
                     }
                  }
                  
                  interlacing = !!bs->GetBit();
                  DPRINTF(XVID_DEBUG_HEADER, "interlacing %i\n", interlacing);
                  
                  if(!bs->GetBit()){
                              //obmc_disable
                     DPRINTF(XVID_DEBUG_ERROR, "obmc_disabled==false not supported\n");
                     /* TODO */
                     /* fucking divx4.02 has this enabled */
                  }
                  
                  sprite_enable = bs->GetBits((vol_ver_id == 1 ? 1 : 2));
                  
                  if(sprite_enable == SPRITE_STATIC || sprite_enable == SPRITE_GMC){
                     int low_latency_sprite_enable;
                     
                     if(sprite_enable != SPRITE_GMC){
                        int sprite_width;
                        int sprite_height;
                        int sprite_left_coord;
                        int sprite_top_coord;
                        sprite_width = bs->GetBits(13);     /* sprite_width */
                        READ_MARKER();
                        sprite_height = bs->GetBits(13); /* sprite_height */
                        READ_MARKER();
                        sprite_left_coord = bs->GetBits(13);   /* sprite_left_coordinate */
                        READ_MARKER();
                        sprite_top_coord = bs->GetBits(13); /* sprite_top_coordinate */
                        READ_MARKER();
                     }
                     sprite_warping_points = bs->GetBits(6);      /* no_of_sprite_warping_points */
                     sprite_warping_accuracy = bs->GetBits(2);    /* sprite_warping_accuracy */
                     sprite_brightness_change = bs->GetBits(1);      /* brightness_change */
                     if (sprite_enable != SPRITE_GMC)
                     {
                        low_latency_sprite_enable = bs->GetBits(1);     /* low_latency_sprite_enable */
                     }
                  }
                  
                  if(vol_ver_id != 1 && shape != VIDOBJLAY_SHAPE_RECTANGULAR){
                              //sadct_disable
                     bs->Skip(1);
                  }
                  
                  if(bs->GetBit()){
                              //not_8_bit
                     DPRINTF(XVID_DEBUG_HEADER, "not_8_bit==true (ignored)\n");
                     quant_bits = bs->GetBits(4);  /* quant_precision */
                     bs->Skip(4);   /* bits_per_pixel */
                  }else{
                     quant_bits = 5;
                  }
                  
                  if(shape == VIDOBJLAY_SHAPE_GRAYSCALE){
                     bs->Skip(1);   /* no_gray_quant_update */
                     bs->Skip(1);   /* composition_method */
                     bs->Skip(1);   /* linear_composition */
                  }
                  
                  quant_type = bs->GetBit();
                  DPRINTF(XVID_DEBUG_HEADER, "quant_type %i\n", quant_type);
                  
                  if(quant_type){
                     if (bs->GetBit()) //load_intra_quant_mat
                     {
                        byte matrix[64];
                        
                        DPRINTF(XVID_DEBUG_HEADER, "load_intra_quant_mat\n");
                        
                        bs->get_matrix(matrix);
                        set_intra_matrix(mpeg_quant_matrices, matrix);
                     }else
                        set_intra_matrix(mpeg_quant_matrices, get_default_intra_matrix());
                     
                     if (bs->GetBit()) /* load_inter_quant_mat */
                     {
                        byte matrix[64];
                        
                        DPRINTF(XVID_DEBUG_HEADER, "load_inter_quant_mat\n");
                        
                        bs->get_matrix(matrix);
                        set_inter_matrix(mpeg_quant_matrices, matrix);
                     }else
                        set_inter_matrix(mpeg_quant_matrices, get_default_inter_matrix());
                     
                     if (shape == VIDOBJLAY_SHAPE_GRAYSCALE) {
                        DPRINTF(XVID_DEBUG_ERROR, "greyscale matrix not supported\n");
                        return -1;
                     }
                     
                  }
                  
                  if(vol_ver_id != 1){
                     quarterpel = bs->GetBit();
                     DPRINTF(XVID_DEBUG_HEADER,"quarterpel %i\n", quarterpel);
                  }else
                     quarterpel = 0;
                  
                  
                  complexity_estimation_disable = bs->GetBit();
                  if(!complexity_estimation_disable){
                     read_vol_complexity_estimation_header(bs);
                  }
                  
                  bs->Skip(1);   //resync_marker_disable
                  
                  if(bs->GetBit()){
                              //data_partitioned
                     DPRINTF(XVID_DEBUG_ERROR, "data_partitioned not supported\n");
                     bs->Skip(1);   /* reversible_vlc */
                  }
                  
                  if(vol_ver_id != 1){
                     newpred_enable = !!bs->GetBit();
                     if (newpred_enable)  /* newpred_enable */
                     {
                        DPRINTF(XVID_DEBUG_HEADER, "+ newpred_enable\n");
                        bs->Skip(2);   /* requested_upstream_message_type */
                        bs->Skip(1);   /* newpred_segment_type */
                     }
                     reduced_resolution_enable = !!bs->GetBit(); //reduced_resolution_vop_enable
                     DPRINTF(XVID_DEBUG_HEADER, "reduced_resolution_enable %i\n", reduced_resolution_enable);
                  }else{
                     newpred_enable = false;
                     reduced_resolution_enable = false;
                  }
                  
                  scalability = (bs->GetBit()!=0);
                  if(scalability){
                     DPRINTF(XVID_DEBUG_ERROR, "scalability not supported\n");
                     bs->Skip(1);   /* hierarchy_type */
                     bs->Skip(4);   /* ref_layer_id */
                     bs->Skip(1);   /* ref_layer_sampling_direc */
                     bs->Skip(5);   /* hor_sampling_factor_n */
                     bs->Skip(5);   /* hor_sampling_factor_m */
                     bs->Skip(5);   /* vert_sampling_factor_n */
                     bs->Skip(5);   /* vert_sampling_factor_m */
                     bs->Skip(1);   /* enhancement_type */
                     if(shape == VIDOBJLAY_SHAPE_BINARY /* && hierarchy_type==0 */) {
                        bs->Skip(1);   /* use_ref_shape */
                        bs->Skip(1);   /* use_ref_texture */
                        bs->Skip(5);   /* shape_hor_sampling_factor_n */
                        bs->Skip(5);   /* shape_hor_sampling_factor_m */
                        bs->Skip(5);   /* shape_vert_sampling_factor_n */
                        bs->Skip(5);   /* shape_vert_sampling_factor_m */
                     }
                     return -1;
                  }
               }else{
                              //shape == BINARY_ONLY
                  if(vol_ver_id != 1){
                     scalability = (bs->GetBit()!=0);
                     if(scalability){
                        DPRINTF(XVID_DEBUG_ERROR, "scalability not supported\n");
                        bs->Skip(4);   /* ref_layer_id */
                        bs->Skip(5);   /* hor_sampling_factor_n */
                        bs->Skip(5);   /* hor_sampling_factor_m */
                        bs->Skip(5);   /* vert_sampling_factor_n */
                        bs->Skip(5);   /* vert_sampling_factor_m */
                        return -1;
                     }
                  }
                  bs->Skip(1);   /* resync_marker_disable */
                  
               }
               
               return (resize ? -3 : -2);   //VOL
               
            }
            break;
         default:
            {
                              //start_code == ?
               //if(bs->ShowBits(24) == 0x000001)
               if((start_code&0x00ffffff) == 0x000001){
                  DPRINTF(XVID_DEBUG_STARTCODE, "<unknown: %x>\n", bs->ShowBits(32));
               }
               bs->Skip(8);
            }
         }
      }
   }

#if 0
   DPRINTF("*** WARNING: no vop_start_code found");
#endif
   return -1;                 //ignore it
}

//----------------------------