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/* gethdr.c, header decoding                                                */

/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */

/*

 * Disclaimer of Warranty

 *

 * These software programs are available to the user without any license fee or

 * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims

 * any and all warranties, whether express, implied, or statuary, including any

 * implied warranties or merchantability or of fitness for a particular

 * purpose.  In no event shall the copyright-holder be liable for any

 * incidental, punitive, or consequential damages of any kind whatsoever

 * arising from the use of these programs.

 *

 * This disclaimer of warranty extends to the user of these programs and user's

 * customers, employees, agents, transferees, successors, and assigns.

 *

 * The MPEG Software Simulation Group does not represent or warrant that the

 * programs furnished hereunder are free of infringement of any third-party

 * patents.

 *

 * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,

 * are subject to royalty fees to patent holders.  Many of these patents are

 * general enough such that they are unavoidable regardless of implementation

 * design.

 *

 */

#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 */

}

/* decode sequence display extension */

static void sequence_display_extension()

{

  int pos;

  pos = ld->Bitcnt;

  video_format      = Get_Bits(3);

  color_description = Get_Bits(1);

  if (color_description)

  {

    color_primaries          = Get_Bits(8);

    transfer_characteristics = Get_Bits(8);

    matrix_coefficients      = Get_Bits(8);

  }

  display_horizontal_size = Get_Bits(14);

  marker_bit("sequence_display_extension");

  display_vertical_size   = Get_Bits(14);

#ifdef VERBOSE

  if (Verbose_Flag>NO_LAYER)

  {

    printf("sequence display extension (byte %d)\n",(pos>>3)-4);

    if (Verbose_Flag>SEQUENCE_LAYER)

    {

      printf("  video_format=%d\n",video_format);

      printf("  color_description=%d\n",color_description);

      if (color_description)

      {

        printf("    color_primaries=%d\n",color_primaries);

        printf("    transfer_characteristics=%d\n",transfer_characteristics);

        printf("    matrix_coefficients=%d\n",matrix_coefficients);

      }

      printf("  display_horizontal_size=%d\n",display_horizontal_size);

      printf("  display_vertical_size=%d\n",display_vertical_size);

    }

  }

#endif /* VERBOSE */

#ifdef VERIFY

  verify_sequence_display_extension++;

#endif /* VERIFY */

}

/* decode quant matrix entension */

/* ISO/IEC 13818-2 section 6.2.3.2 */

static void quant_matrix_extension()

{

  int i;

  int pos;

  pos = ld->Bitcnt;

  if((ld->load_intra_quantizer_matrix = Get_Bits(1)))

  {

    for (i=0; i<64; i++)

    {

      ld->chroma_intra_quantizer_matrix[scan[ZIG_ZAG][i]]

      = ld->intra_quantizer_matrix[scan[ZIG_ZAG][i]]

      = Get_Bits(8);

    }

  }

  if((ld->load_non_intra_quantizer_matrix = Get_Bits(1)))

  {

    for (i=0; i<64; i++)

    {

      ld->chroma_non_intra_quantizer_matrix[scan[ZIG_ZAG][i]]

      = ld->non_intra_quantizer_matrix[scan[ZIG_ZAG][i]]

      = Get_Bits(8);

    }

  }

  if((ld->load_chroma_intra_quantizer_matrix = Get_Bits(1)))

  {

    for (i=0; i<64; i++)

      ld->chroma_intra_quantizer_matrix[scan[ZIG_ZAG][i]] = Get_Bits(8);

  }

  if((ld->load_chroma_non_intra_quantizer_matrix = Get_Bits(1)))

  {

    for (i=0; i<64; i++)

      ld->chroma_non_intra_quantizer_matrix[scan[ZIG_ZAG][i]] = Get_Bits(8);

  }

#ifdef VERBOSE

  if (Verbose_Flag>NO_LAYER)

  {

    printf("quant matrix extension (byte %d)\n",(pos>>3)-4);

    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);

    printf("  load_chroma_intra_quantizer_matrix=%d\n",

      ld->load_chroma_intra_quantizer_matrix);

    printf("  load_chroma_non_intra_quantizer_matrix=%d\n",

      ld->load_chroma_non_intra_quantizer_matrix);

  }

#endif /* VERBOSE */

#ifdef VERIFY

  verify_quant_matrix_extension++;

#endif /* VERIFY */

}

/* decode sequence scalable extension */

/* ISO/IEC 13818-2   section 6.2.2.5 */

static void sequence_scalable_extension()

{

  int pos;

  pos = ld->Bitcnt;

  /* values (without the +1 offset) of scalable_mode are defined in

     Table 6-10 of ISO/IEC 13818-2 */

  ld->scalable_mode = Get_Bits(2) + 1; /* add 1 to make SC_DP != SC_NONE */

  layer_id = Get_Bits(4);

  if (ld->scalable_mode==SC_SPAT)

  {

    lower_layer_prediction_horizontal_size = Get_Bits(14);

    marker_bit("sequence_scalable_extension()");

    lower_layer_prediction_vertical_size   = Get_Bits(14);

    horizontal_subsampling_factor_m        = Get_Bits(5);

    horizontal_subsampling_factor_n        = Get_Bits(5);

    vertical_subsampling_factor_m          = Get_Bits(5);

    vertical_subsampling_factor_n          = Get_Bits(5);

  }

  if (ld->scalable_mode==SC_TEMP)

    Error("temporal scalability not implemented\n");

#ifdef VERBOSE

  if (Verbose_Flag>NO_LAYER)

  {

    printf("sequence scalable extension (byte %d)\n",(pos>>3)-4);

    if (Verbose_Flag>SEQUENCE_LAYER)

    {

      printf("  scalable_mode=%d\n",ld->scalable_mode-1);

      printf("  layer_id=%d\n",layer_id);

      if (ld->scalable_mode==SC_SPAT)

      {

        printf("    lower_layer_prediction_horiontal_size=%d\n",

          lower_layer_prediction_horizontal_size);

        printf("    lower_layer_prediction_vertical_size=%d\n",

          lower_layer_prediction_vertical_size);

        printf("    horizontal_subsampling_factor_m=%d\n",

          horizontal_subsampling_factor_m);

        printf("    horizontal_subsampling_factor_n=%d\n",

          horizontal_subsampling_factor_n);

        printf("    vertical_subsampling_factor_m=%d\n",

          vertical_subsampling_factor_m);

        printf("    vertical_subsampling_factor_n=%d\n",

          vertical_subsampling_factor_n);

      }

    }

  }

#endif /* VERBOSE */

#ifdef VERIFY

  verify_sequence_scalable_extension++;

#endif /* VERIFY */

}

/* decode picture display extension */

/* ISO/IEC 13818-2 section 6.2.3.3. */

static void picture_display_extension()

{

  int i;

  int number_of_frame_center_offsets;

  int pos;

  pos = ld->Bitcnt;

  /* based on ISO/IEC 13818-2 section 6.3.12

    (November 1994) Picture display extensions */

  /* derive number_of_frame_center_offsets */

  if(progressive_sequence)

  {

    if(repeat_first_field)

    {

      if(top_field_first)

        number_of_frame_center_offsets = 3;

      else

        number_of_frame_center_offsets = 2;

    }

    else

    {

      number_of_frame_center_offsets = 1;

    }

  }

  else

  {

    if(picture_structure!=FRAME_PICTURE)

    {

      number_of_frame_center_offsets = 1;

    }

    else

    {

      if(repeat_first_field)

        number_of_frame_center_offsets = 3;

      else

        number_of_frame_center_offsets = 2;

    }

  }

  /* now parse */

  for (i=0; i<number_of_frame_center_offsets; i++)

  {

    frame_center_horizontal_offset[i] = Get_Bits(16);

    marker_bit("picture_display_extension, first marker bit");

    frame_center_vertical_offset[i]   = Get_Bits(16);

    marker_bit("picture_display_extension, second marker bit");

  }

#ifdef VERBOSE

  if (Verbose_Flag>NO_LAYER)

  {

    printf("picture display extension (byte %d)\n",(pos>>3)-4);

    if (Verbose_Flag>SEQUENCE_LAYER)

    {

      for (i=0; i<number_of_frame_center_offsets; i++)

      {

        printf("  frame_center_horizontal_offset[%d]=%d\n",i,

          frame_center_horizontal_offset[i]);

        printf("  frame_center_vertical_offset[%d]=%d\n",i,

          frame_center_vertical_offset[i]);