static void encoder_state_write_bitstream_vid_parameter_set(encoder_state * const encoder_state)
{
  bitstream * const stream = &encoder_state->stream;
  int i;
#ifdef _DEBUG
  printf("=========== Video Parameter Set ID: 0 ===========\n");
#endif

  WRITE_U(stream, 0, 4, "vps_video_parameter_set_id");
  WRITE_U(stream, 3, 2, "vps_reserved_three_2bits" );
  WRITE_U(stream, 0, 6, "vps_reserved_zero_6bits" );
  WRITE_U(stream, 1, 3, "vps_max_sub_layers_minus1");
  WRITE_U(stream, 0, 1, "vps_temporal_id_nesting_flag");
  WRITE_U(stream, 0xffff, 16, "vps_reserved_ffff_16bits");

  encoder_state_write_bitstream_PTL(encoder_state);

  WRITE_U(stream, 0, 1, "vps_sub_layer_ordering_info_present_flag");

  //for each layer
  for (i = 0; i < 1; i++) {
  WRITE_UE(stream, 1, "vps_max_dec_pic_buffering");
  WRITE_UE(stream, 0, "vps_num_reorder_pics");
  WRITE_UE(stream, 0, "vps_max_latency_increase");
  }

  WRITE_U(stream, 0, 6, "vps_max_nuh_reserved_zero_layer_id");
  WRITE_UE(stream, 0, "vps_max_op_sets_minus1");
  WRITE_U(stream, 0, 1, "vps_timing_info_present_flag");

  //IF timing info
  //END IF

  WRITE_U(stream, 0, 1, "vps_extension_flag");
}
static void encoder_state_write_bitstream_access_unit_delimiter(encoder_state * const encoder_state)
{
  bitstream * const stream = &encoder_state->stream;
  uint8_t pic_type = encoder_state->global->slicetype == SLICE_I ? 0
                   : encoder_state->global->slicetype == SLICE_P ? 1
                   :                                             2;
  WRITE_U(stream, pic_type, 3, "pic_type");
}
static void encoder_state_write_bitstream_scaling_list(encoder_state_t * const state)
{
  const encoder_control_t * const encoder = state->encoder_control;
  bitstream_t * const stream = &state->stream;
  uint32_t size_id;
  for (size_id = 0; size_id < SCALING_LIST_SIZE_NUM; size_id++) {
    int32_t list_id;
    for (list_id = 0; list_id < kvz_g_scaling_list_num[size_id]; list_id++) {
      uint8_t scaling_list_pred_mode_flag = 1;
      int32_t pred_list_idx;
      int32_t i;
      uint32_t ref_matrix_id = UINT32_MAX;

      for (pred_list_idx = list_id; pred_list_idx >= 0; pred_list_idx--) {
        const int32_t * const pred_list  = (list_id == pred_list_idx) ?
                                     kvz_scalinglist_get_default(size_id, pred_list_idx) :
                                     encoder->scaling_list.scaling_list_coeff[size_id][pred_list_idx];

        if (!memcmp(encoder->scaling_list.scaling_list_coeff[size_id][list_id], pred_list, sizeof(int32_t) * MIN(8, kvz_g_scaling_list_size[size_id])) &&
            ((size_id < SCALING_LIST_16x16) ||
             (encoder->scaling_list.scaling_list_dc[size_id][list_id] == encoder->scaling_list.scaling_list_dc[size_id][pred_list_idx]))) {
          ref_matrix_id = pred_list_idx;
          scaling_list_pred_mode_flag = 0;
          break;
        }
      }
      WRITE_U(stream, scaling_list_pred_mode_flag, 1, "scaling_list_pred_mode_flag" );

      if (!scaling_list_pred_mode_flag) {
        WRITE_UE(stream, list_id - ref_matrix_id, "scaling_list_pred_matrix_id_delta");
      } else {
        int32_t delta;
        const int32_t coef_num = MIN(MAX_MATRIX_COEF_NUM, kvz_g_scaling_list_size[size_id]);
        const uint32_t * const scan_cg = (size_id == 0) ? g_sig_last_scan_16x16 : g_sig_last_scan_32x32;
        int32_t next_coef = 8;
        const int32_t * const coef_list = encoder->scaling_list.scaling_list_coeff[size_id][list_id];

        if (size_id >= SCALING_LIST_16x16) {
          WRITE_SE(stream, encoder->scaling_list.scaling_list_dc[size_id][list_id] - 8, "scaling_list_dc_coef_minus8");
          next_coef = encoder->scaling_list.scaling_list_dc[size_id][list_id];
        }

        for (i = 0; i < coef_num; i++) {
          delta     = coef_list[scan_cg[i]] - next_coef;
          next_coef = coef_list[scan_cg[i]];
          if (delta > 127)
            delta -= 256;
          if (delta < -128)
            delta += 256;

          WRITE_SE(stream, delta, "scaling_list_delta_coef");
        }
      }
    }
  }
}
static void encoder_state_write_bitstream_seq_parameter_set(encoder_state_t * const state)
{
  bitstream_t * const stream = &state->stream;
  const encoder_control_t * encoder = state->encoder_control;

#ifdef KVZ_DEBUG
  printf("=========== Sequence Parameter Set ID: 0 ===========\n");
#endif

  // TODO: profile IDC and level IDC should be defined later on
  WRITE_U(stream, 0, 4, "sps_video_parameter_set_id");
  WRITE_U(stream, 1, 3, "sps_max_sub_layers_minus1");
  WRITE_U(stream, 0, 1, "sps_temporal_id_nesting_flag");

  encoder_state_write_bitstream_PTL(state);

  WRITE_UE(stream, 0, "sps_seq_parameter_set_id");
  WRITE_UE(stream, state->encoder_control->in.video_format,
           "chroma_format_idc");

  if (state->encoder_control->in.video_format == 3) {
    WRITE_U(stream, 0, 1, "separate_colour_plane_flag");
  }

  WRITE_UE(stream, encoder->in.width, "pic_width_in_luma_samples");
  WRITE_UE(stream, encoder->in.height, "pic_height_in_luma_samples");

  if (encoder->in.width != encoder->in.real_width || encoder->in.height != encoder->in.real_height) {
    // The standard does not seem to allow setting conf_win values such that
    // the number of luma samples is not a multiple of 2. Options are to either
    // hide one line or show an extra line of non-video. Neither seems like a
    // very good option, so let's not even try.
    assert(!(encoder->in.width % 2));
    WRITE_U(stream, 1, 1, "conformance_window_flag");
    WRITE_UE(stream, 0, "conf_win_left_offset");
    WRITE_UE(stream, (encoder->in.width - encoder->in.real_width) >> 1,
             "conf_win_right_offset");
    WRITE_UE(stream, 0, "conf_win_top_offset");
    WRITE_UE(stream, (encoder->in.height - encoder->in.real_height) >> 1,
             "conf_win_bottom_offset");
  } else {
static void encoder_state_write_bitstream_aud(encoder_state_t * const state)
{
  bitstream_t * const stream = &state->stream;
  kvz_nal_write(stream, KVZ_NAL_AUD_NUT, 0, 1);

  uint8_t pic_type = state->global->slicetype == KVZ_SLICE_I ? 0
                   : state->global->slicetype == KVZ_SLICE_P ? 1
                   :                                       2;
  WRITE_U(stream, pic_type, 3, "pic_type");

  kvz_bitstream_add_rbsp_trailing_bits(stream);
}
static void encoder_state_write_bitstream_PTL(encoder_state_t * const state)
{
  bitstream_t * const stream = &state->stream;
  int i;
  // PTL
  // Profile Tier
  WRITE_U(stream, 0, 2, "general_profile_space");
  WRITE_U(stream, 0, 1, "general_tier_flag");
  // Main Profile == 1,  Main 10 profile == 2
  WRITE_U(stream, (state->encoder_control->bitdepth == 8)?1:2, 5, "general_profile_idc");
  /* Compatibility flags should be set at general_profile_idc
   *  (so with general_profile_idc = 1, compatibility_flag[1] should be 1)
   * According to specification, when compatibility_flag[1] is set,
   *  compatibility_flag[2] should be set too.
   */
  WRITE_U(stream, 3<<29, 32, "general_profile_compatibility_flag[]");

  WRITE_U(stream, 1, 1, "general_progressive_source_flag");
  WRITE_U(stream, state->encoder_control->in.source_scan_type!= 0, 1, "general_interlaced_source_flag");
  WRITE_U(stream, 0, 1, "general_non_packed_constraint_flag");
  WRITE_U(stream, 0, 1, "general_frame_only_constraint_flag");

  WRITE_U(stream, 0, 32, "XXX_reserved_zero_44bits[0..31]");
  WRITE_U(stream, 0, 12, "XXX_reserved_zero_44bits[32..43]");

  // end Profile Tier

  // Level 6.2 (general_level_idc is 30 * 6.2)
  WRITE_U(stream, 186, 8, "general_level_idc");

  WRITE_U(stream, 0, 1, "sub_layer_profile_present_flag");
  WRITE_U(stream, 0, 1, "sub_layer_level_present_flag");

  for (i = 1; i < 8; i++) {
    WRITE_U(stream, 0, 2, "reserved_zero_2bits");
  }

  // end PTL
}
static void encoder_state_write_bitstream_VUI(encoder_state_t * const state)
{
  bitstream_t * const stream = &state->stream;
  const encoder_control_t * const encoder = state->encoder_control;
#ifdef KVZ_DEBUG
  printf("=========== VUI Set ID: 0 ===========\n");
#endif
  if (encoder->vui.sar_width > 0 && encoder->vui.sar_height > 0) {
    int i;
    static const struct
    {
      uint8_t width;
      uint8_t height;
      uint8_t idc;
    } sar[] = {
      // aspect_ratio_idc = 0 -> unspecified
      {  1,  1, 1 }, { 12, 11, 2 }, { 10, 11, 3 }, { 16, 11, 4 },
      { 40, 33, 5 }, { 24, 11, 6 }, { 20, 11, 7 }, { 32, 11, 8 },
      { 80, 33, 9 }, { 18, 11, 10}, { 15, 11, 11}, { 64, 33, 12},
      {160, 99, 13}, {  4,  3, 14}, {  3,  2, 15}, {  2,  1, 16},
      // aspect_ratio_idc = [17..254] -> reserved
      { 0, 0, 255 }
    };

    for (i = 0; sar[i].idc != 255; i++)
      if (sar[i].width  == encoder->vui.sar_width &&
          sar[i].height == encoder->vui.sar_height)
        break;

    WRITE_U(stream, 1, 1, "aspect_ratio_info_present_flag");
    WRITE_U(stream, sar[i].idc, 8, "aspect_ratio_idc");
    if (sar[i].idc == 255) {
      // EXTENDED_SAR
      WRITE_U(stream, encoder->vui.sar_width, 16, "sar_width");
      WRITE_U(stream, encoder->vui.sar_height, 16, "sar_height");
    }
  } else
    WRITE_U(stream, 0, 1, "aspect_ratio_info_present_flag");

  //IF aspect ratio info
  //ENDIF

  if (encoder->vui.overscan > 0) {
    WRITE_U(stream, 1, 1, "overscan_info_present_flag");
    WRITE_U(stream, encoder->vui.overscan - 1, 1, "overscan_appropriate_flag");
  } else
    WRITE_U(stream, 0, 1, "overscan_info_present_flag");

  //IF overscan info
  //ENDIF

  if (encoder->vui.videoformat != 5 || encoder->vui.fullrange ||
      encoder->vui.colorprim != 2 || encoder->vui.transfer != 2 ||
      encoder->vui.colormatrix != 2) {
    WRITE_U(stream, 1, 1, "video_signal_type_present_flag");
    WRITE_U(stream, encoder->vui.videoformat, 3, "video_format");
    WRITE_U(stream, encoder->vui.fullrange, 1, "video_full_range_flag");

    if (encoder->vui.colorprim != 2 || encoder->vui.transfer != 2 ||
        encoder->vui.colormatrix != 2) {
      WRITE_U(stream, 1, 1, "colour_description_present_flag");
      WRITE_U(stream, encoder->vui.colorprim, 8, "colour_primaries");
      WRITE_U(stream, encoder->vui.transfer, 8, "transfer_characteristics");
      WRITE_U(stream, encoder->vui.colormatrix, 8, "matrix_coeffs");
    } else
      WRITE_U(stream, 0, 1, "colour_description_present_flag");
  } else
    WRITE_U(stream, 0, 1, "video_signal_type_present_flag");

  //IF video type
  //ENDIF

  if (encoder->vui.chroma_loc > 0) {
    WRITE_U(stream, 1, 1, "chroma_loc_info_present_flag");
    WRITE_UE(stream, encoder->vui.chroma_loc, "chroma_sample_loc_type_top_field");
    WRITE_UE(stream, encoder->vui.chroma_loc, "chroma_sample_loc_type_bottom_field");
  } else
    WRITE_U(stream, 0, 1, "chroma_loc_info_present_flag");

  //IF chroma loc info
  //ENDIF

  WRITE_U(stream, 0, 1, "neutral_chroma_indication_flag");
  WRITE_U(stream, state->encoder_control->vui.field_seq_flag, 1, "field_seq_flag"); // 0: frames, 1: fields
  WRITE_U(stream, state->encoder_control->vui.frame_field_info_present_flag, 1, "frame_field_info_present_flag");
  WRITE_U(stream, 0, 1, "default_display_window_flag");

  //IF default display window
  //ENDIF

  WRITE_U(stream, 0, 1, "vui_timing_info_present_flag");

  //IF timing info
  //ENDIF

  WRITE_U(stream, 0, 1, "bitstream_restriction_flag");

  //IF bitstream restriction
  //ENDIF
}
static void encoder_state_write_bitstream_SPS_extension(bitstream_t *stream,
                                                        encoder_state_t * const state)
{
  const kvz_config *cfg = &state->encoder_control->cfg;
  if (cfg->implicit_rdpcm && cfg->lossless) {
    WRITE_U(stream, 1, 1, "sps_extension_present_flag");

    WRITE_U(stream, 1, 1, "sps_range_extension_flag");
    WRITE_U(stream, 0, 1, "sps_multilayer_extension_flag");
    WRITE_U(stream, 0, 1, "sps_3d_extension_flag");
    WRITE_U(stream, 0, 5, "sps_extension_5bits");

    WRITE_U(stream, 0, 1, "transform_skip_rotation_enabled_flag");
    WRITE_U(stream, 0, 1, "transform_skip_context_enabled_flag");
    WRITE_U(stream, 1, 1, "implicit_rdpcm_enabled_flag");
    WRITE_U(stream, 0, 1, "explicit_rdpcm_enabled_flag");
    WRITE_U(stream, 0, 1, "extended_precision_processing_flag");
    WRITE_U(stream, 0, 1, "intra_smoothing_disabled_flag");
    WRITE_U(stream, 0, 1, "high_precision_offsets_enabled_flag");
    WRITE_U(stream, 0, 1, "persistent_rice_adaptation_enabled_flag");
    WRITE_U(stream, 0, 1, "cabac_bypass_alignment_enabled_flag");
  } else {
    WRITE_U(stream, 0, 1, "sps_extension_present_flag");
  }
}