/* gethdr.c, 頭信息解碼                                             */#include <stdio.h>#include "config.h"#include "global.h"/* private prototypes */static void sequence_header _ANSI_ARGS_((void));static void group_of_pictures_header _ANSI_ARGS_((void));static void picture_header _ANSI_ARGS_((void));static void extension_and_user_data _ANSI_ARGS_((void));static void sequence_extension _ANSI_ARGS_((void));static void sequence_display_extension _ANSI_ARGS_((void));static void quant_matrix_extension _ANSI_ARGS_((void));static void sequence_scalable_extension _ANSI_ARGS_((void));static void picture_display_extension _ANSI_ARGS_((void));static void picture_coding_extension _ANSI_ARGS_((void));static void picture_spatial_scalable_extension _ANSI_ARGS_((void));static void picture_temporal_scalable_extension _ANSI_ARGS_((void));static int  extra_bit_information _ANSI_ARGS_((void));static void copyright_extension _ANSI_ARGS_((void));static void user_data _ANSI_ARGS_((void));static void user_data _ANSI_ARGS_((void));/* introduced in September 1995 to assist spatial scalable decoding */static void Update_Temporal_Reference_Tacking_Data _ANSI_ARGS_((void));/* private variables */static int Temporal_Reference_Base = 0;static int True_Framenum_max  = -1;static int Temporal_Reference_GOP_Reset = 0;#define RESERVED    -1 static double frame_rate_Table[16] ={  0.0,  ((23.0*1000.0)/1001.0),  24.0,  25.0,  ((30.0*1000.0)/1001.0),  30.0,  50.0,  ((60.0*1000.0)/1001.0),  60.0,   RESERVED,  RESERVED,  RESERVED,  RESERVED,  RESERVED,  RESERVED,  RESERVED};/* * decode headers from one input stream * until an End of Sequence or picture start code * is found */int Get_Hdr(){  unsigned int code;  for (;;)  {    /* look for next_start_code */    next_start_code();    code = Get_Bits32();      switch (code)    {    case SEQUENCE_HEADER_CODE:      sequence_header();      break;    case GROUP_START_CODE:      group_of_pictures_header();      break;    case PICTURE_START_CODE:      picture_header();      return 1;      break;    case SEQUENCE_END_CODE:      return 0;      break;    default:      if (!Quiet_Flag)        fprintf(stderr,"Unexpected next_start_code %08x (ignored)\n",code);      break;    }  }}/* align to start of next next_start_code */void next_start_code(){  /* byte align */  Flush_Buffer(ld->Incnt&7);  while (Show_Bits(24)!=0x01L)    Flush_Buffer(8);}/* decode sequence header */static void sequence_header(){  int i;  int pos;  pos = ld->Bitcnt;  horizontal_size             = Get_Bits(12);  vertical_size               = Get_Bits(12);  aspect_ratio_information    = Get_Bits(4);  frame_rate_code             = Get_Bits(4);  bit_rate_value              = Get_Bits(18);  marker_bit("sequence_header()");  vbv_buffer_size             = Get_Bits(10);  constrained_parameters_flag = Get_Bits(1);  if((ld->load_intra_quantizer_matrix = Get_Bits(1)))  {    for (i=0; i<64; i++)      ld->intra_quantizer_matrix[scan[ZIG_ZAG][i]] = Get_Bits(8);  }  else  {    for (i=0; i<64; i++)      ld->intra_quantizer_matrix[i] = default_intra_quantizer_matrix[i];  }  if((ld->load_non_intra_quantizer_matrix = Get_Bits(1)))  {    for (i=0; i<64; i++)      ld->non_intra_quantizer_matrix[scan[ZIG_ZAG][i]] = Get_Bits(8);  }  else  {    for (i=0; i<64; i++)      ld->non_intra_quantizer_matrix[i] = 16;  }  /* copy luminance to chrominance matrices */  for (i=0; i<64; i++)  {    ld->chroma_intra_quantizer_matrix[i] =      ld->intra_quantizer_matrix[i];    ld->chroma_non_intra_quantizer_matrix[i] =      ld->non_intra_quantizer_matrix[i];  }#ifdef VERBOSE  if (Verbose_Flag > NO_LAYER)  {    printf("sequence header (byte %d)\n",(pos>>3)-4);    if (Verbose_Flag > SEQUENCE_LAYER)    {      printf("  horizontal_size=%d\n",horizontal_size);      printf("  vertical_size=%d\n",vertical_size);      printf("  aspect_ratio_information=%d\n",aspect_ratio_information);      printf("  frame_rate_code=%d",frame_rate_code);      printf("  bit_rate_value=%d\n",bit_rate_value);      printf("  vbv_buffer_size=%d\n",vbv_buffer_size);      printf("  constrained_parameters_flag=%d\n",constrained_parameters_flag);      printf("  load_intra_quantizer_matrix=%d\n",ld->load_intra_quantizer_matrix);      printf("  load_non_intra_quantizer_matrix=%d\n",ld->load_non_intra_quantizer_matrix);    }  }#endif /* VERBOSE */#ifdef VERIFY  verify_sequence_header++;#endif /* VERIFY */  extension_and_user_data();}/* decode group of pictures header *//* ISO/IEC 13818-2 section 6.2.2.6 */static void group_of_pictures_header(){  int pos;  if (ld == &base)  {    Temporal_Reference_Base = True_Framenum_max + 1; 	/* *CH* */    Temporal_Reference_GOP_Reset = 1;  }  pos = ld->Bitcnt;  drop_flag   = Get_Bits(1);  hour        = Get_Bits(5);  minute      = Get_Bits(6);  marker_bit("group_of_pictures_header()");  sec         = Get_Bits(6);  frame       = Get_Bits(6);  closed_gop  = Get_Bits(1);  broken_link = Get_Bits(1);#ifdef VERBOSE  if (Verbose_Flag > NO_LAYER)  {    printf("group of pictures (byte %d)\n",(pos>>3)-4);    if (Verbose_Flag > SEQUENCE_LAYER)    {      printf("  drop_flag=%d\n",drop_flag);      printf("  timecode %d:%02d:%02d:%02d\n",hour,minute,sec,frame);      printf("  closed_gop=%d\n",closed_gop);      printf("  broken_link=%d\n",broken_link);    }  }#endif /* VERBOSE */#ifdef VERIFY  verify_group_of_pictures_header++;#endif /* VERIFY */  extension_and_user_data();}/* decode picture header *//* ISO/IEC 13818-2 section 6.2.3 */static void picture_header(){  int pos;  int Extra_Information_Byte_Count;  /* unless later overwritten by picture_spatial_scalable_extension() */  ld->pict_scal = 0;     pos = ld->Bitcnt;  temporal_reference  = Get_Bits(10);  picture_coding_type = Get_Bits(3);  vbv_delay           = Get_Bits(16);  if (picture_coding_type==P_TYPE || picture_coding_type==B_TYPE)  {    full_pel_forward_vector = Get_Bits(1);    forward_f_code = Get_Bits(3);  }  if (picture_coding_type==B_TYPE)  {    full_pel_backward_vector = Get_Bits(1);    backward_f_code = Get_Bits(3);  }#ifdef VERBOSE  if (Verbose_Flag>NO_LAYER)  {    printf("picture header (byte %d)\n",(pos>>3)-4);    if (Verbose_Flag>SEQUENCE_LAYER)    {      printf("  temporal_reference=%d\n",temporal_reference);      printf("  picture_coding_type=%d\n",picture_coding_type);      printf("  vbv_delay=%d\n",vbv_delay);      if (picture_coding_type==P_TYPE || picture_coding_type==B_TYPE)      {        printf("  full_pel_forward_vector=%d\n",full_pel_forward_vector);        printf("  forward_f_code =%d\n",forward_f_code);      }      if (picture_coding_type==B_TYPE)      {        printf("  full_pel_backward_vector=%d\n",full_pel_backward_vector);        printf("  backward_f_code =%d\n",backward_f_code);      }    }  }#endif /* VERBOSE */#ifdef VERIFY  verify_picture_header++;#endif /* VERIFY */  Extra_Information_Byte_Count =     extra_bit_information();    extension_and_user_data();  /* update tracking information used to assist spatial scalability */  Update_Temporal_Reference_Tacking_Data();}/* decode slice header *//* ISO/IEC 13818-2 section 6.2.4 */int slice_header(){  int slice_vertical_position_extension;  int quantizer_scale_code;  int pos;  int slice_picture_id_enable = 0;  int slice_picture_id = 0;  int extra_information_slice = 0;  pos = ld->Bitcnt;  slice_vertical_position_extension =    (ld->MPEG2_Flag && vertical_size>2800) ? Get_Bits(3) : 0;  if (ld->scalable_mode==SC_DP)    ld->priority_breakpoint = Get_Bits(7);  quantizer_scale_code = Get_Bits(5);  ld->quantizer_scale =    ld->MPEG2_Flag ? (ld->q_scale_type ? Non_Linear_quantizer_scale[quantizer_scale_code] : quantizer_scale_code<<1) : quantizer_scale_code;  /* slice_id introduced in March 1995 as part of the video corridendum     (after the IS was drafted in November 1994) */  if (Get_Bits(1))  {    ld->intra_slice = Get_Bits(1);    slice_picture_id_enable = Get_Bits(1);	slice_picture_id = Get_Bits(6);    extra_information_slice = extra_bit_information();  }  else    ld->intra_slice = 0;#ifdef VERBOSE  if (Verbose_Flag>PICTURE_LAYER)  {    printf("slice header (byte %d)\n",(pos>>3)-4);    if (Verbose_Flag>SLICE_LAYER)    {      if (ld->MPEG2_Flag && vertical_size>2800)        printf("  slice_vertical_position_extension=%d\n",slice_vertical_position_extension);        if (ld->scalable_mode==SC_DP)        printf("  priority_breakpoint=%d\n",ld->priority_breakpoint);      printf("  quantizer_scale_code=%d\n",quantizer_scale_code);      printf("  slice_picture_id_enable = %d\n", slice_picture_id_enable);      if(slice_picture_id_enable)        printf("  slice_picture_id = %d\n", slice_picture_id);    }  }#endif /* VERBOSE */#ifdef VERIFY  verify_slice_header++;#endif /* VERIFY */  return slice_vertical_position_extension;}/* decode extension and user data *//* ISO/IEC 13818-2 section 6.2.2.2 */static void extension_and_user_data(){  int code,ext_ID;  next_start_code();  while ((code = Show_Bits(32))==EXTENSION_START_CODE || code==USER_DATA_START_CODE)  {    if (code==EXTENSION_START_CODE)    {      Flush_Buffer32();      ext_ID = Get_Bits(4);      switch (ext_ID)      {      case SEQUENCE_EXTENSION_ID:        sequence_extension();        break;      case SEQUENCE_DISPLAY_EXTENSION_ID:        sequence_display_extension();        break;      case QUANT_MATRIX_EXTENSION_ID:        quant_matrix_extension();        break;      case SEQUENCE_SCALABLE_EXTENSION_ID:        sequence_scalable_extension();        break;      case PICTURE_DISPLAY_EXTENSION_ID:        picture_display_extension();        break;      case PICTURE_CODING_EXTENSION_ID:        picture_coding_extension();        break;      case PICTURE_SPATIAL_SCALABLE_EXTENSION_ID:        picture_spatial_scalable_extension();        break;      case PICTURE_TEMPORAL_SCALABLE_EXTENSION_ID:        picture_temporal_scalable_extension();        break;      case COPYRIGHT_EXTENSION_ID:        copyright_extension();        break;     default:        fprintf(stderr,"reserved extension start code ID %d\n",ext_ID);        break;      }      next_start_code();    }    else    {#ifdef VERBOSE      if (Verbose_Flag>NO_LAYER)        printf("user data\n");#endif /* VERBOSE */      Flush_Buffer32();      user_data();    }  }}/* decode sequence extension *//* ISO/IEC 13818-2 section 6.2.2.3 */static void sequence_extension(){  int horizontal_size_extension;  int vertical_size_extension;  int bit_rate_extension;  int vbv_buffer_size_extension;  int pos;  /* derive bit position for trace */#ifdef VERBOSE  pos = ld->Bitcnt;#endif  ld->MPEG2_Flag = 1;  ld->scalable_mode = SC_NONE; /* unless overwritten by sequence_scalable_extension() */  layer_id = 0;                /* unless overwritten by sequence_scalable_extension() */    profile_and_level_indication = Get_Bits(8);  progressive_sequence         = Get_Bits(1);  chroma_format                = Get_Bits(2);  horizontal_size_extension    = Get_Bits(2);  vertical_size_extension      = Get_Bits(2);  bit_rate_extension           = Get_Bits(12);  marker_bit("sequence_extension");  vbv_buffer_size_extension    = Get_Bits(8);  low_delay                    = Get_Bits(1);  frame_rate_extension_n       = Get_Bits(2);  frame_rate_extension_d       = Get_Bits(5);  frame_rate = frame_rate_Table[frame_rate_code] *    ((frame_rate_extension_n+1)/(frame_rate_extension_d+1));  /* special case for 422 profile & level must be made */  if((profile_and_level_indication>>7) & 1)  {  /* escape bit of profile_and_level_indication set */      /* 4:2:2 Profile @ Main Level */    if((profile_and_level_indication&15)==5)    {      profile = PROFILE_422;      level   = MAIN_LEVEL;      }  }  else  {    profile = profile_and_level_indication >> 4;  /* Profile is upper nibble */    level   = profile_and_level_indication & 0xF;  /* Level is lower nibble */  }     horizontal_size = (horizontal_size_extension<<12) | (horizontal_size&0x0fff);  vertical_size = (vertical_size_extension<<12) | (vertical_size&0x0fff);  /* ISO/IEC 13818-2 does not define bit_rate_value to be composed of   * both the original bit_rate_value parsed in sequence_header() and   * the optional bit_rate_extension in sequence_extension_header().    * However, we use it for bitstream verification purposes.    */  bit_rate_value += (bit_rate_extension << 18);  bit_rate = ((double) bit_rate_value) * 400.0;  vbv_buffer_size += (vbv_buffer_size_extension << 10);#ifdef VERBOSE  if (Verbose_Flag>NO_LAYER)  {    printf("sequence extension (byte %d)\n",(pos>>3)-4);    if (Verbose_Flag>SEQUENCE_LAYER)    {      printf("  profile_and_level_indication=%d\n",profile_and_level_indication);      if (profile_and_level_indication<128)      {        printf("    profile=%d, level=%d\n",profile,level);      }      printf("  progressive_sequence=%d\n",progressive_sequence);      printf("  chroma_format=%d\n",chroma_format);      printf("  horizontal_size_extension=%d\n",horizontal_size_extension);      printf("  vertical_size_extension=%d\n",vertical_size_extension);      printf("  bit_rate_extension=%d\n",bit_rate_extension);      printf("  vbv_buffer_size_extension=%d\n",vbv_buffer_size_extension);      printf("  low_delay=%d\n",low_delay);      printf("  frame_rate_extension_n=%d\n",frame_rate_extension_n);      printf("  frame_rate_extension_d=%d\n",frame_rate_extension_d);    }  }#endif /* VERBOSE */#ifdef VERIFY  verify_sequence_extension++;#endif /* VERIFY */}