func: static inline int parse_nal_units(AVCodecParserContext *s,
  
                                    AVCodecContext *avctx,
  
                                    const uint8_t *buf, int buf_size)
  
  {
  
      H264ParseContext *p = s->priv_data;
  
      const uint8_t *buf_end = buf + buf_size;
  
  
  
      H2645NAL nal = { NULL };
  
  
  
      unsigned int pps_id;
  
      unsigned int slice_type;
  
      int state = -1, got_reset = 0;
  
      int field_poc[2];
  
      int ret;
  
  
  
      /* set some sane default values */
  
      s->pict_type         = AV_PICTURE_TYPE_I;
  
      s->key_frame         = 0;
  
      s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
  
  
  
      ff_h264_sei_uninit(&p->sei);
  
  
  
      if (!buf_size)
  
          return 0;
  
  
  
      for (;;) {
  
          const SPS *sps;
  
          int src_length, consumed;
  
          buf = avpriv_find_start_code(buf, buf_end, &state);
  
          if (buf >= buf_end)
  
              break;
  
          --buf;
  
          src_length = buf_end - buf;
  
          switch (state & 0x1f) {
  
          case H264_NAL_SLICE:
  
          case H264_NAL_IDR_SLICE:
  
              // Do not walk the whole buffer just to decode slice header
  
              if ((state & 0x1f) == H264_NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
  
                  /* IDR or disposable slice
  
                   * No need to decode many bytes because MMCOs shall not be present. */
  
                  if (src_length > 60)
  
                      src_length = 60;
  
              } else {
  
                  /* To decode up to MMCOs */
  
                  if (src_length > 1000)
  
                      src_length = 1000;
  
              }
  
              break;
  
          }
  
  
  
          consumed = ff_h2645_extract_rbsp(buf, src_length, &nal);
  
          if (consumed < 0)
  
              break;
  
  
  
          ret = init_get_bits(&nal.gb, nal.data, nal.size * 8);
  
          if (ret < 0)
  
              goto fail;
  
          get_bits1(&nal.gb);
  
          nal.ref_idc = get_bits(&nal.gb, 2);
  
          nal.type    = get_bits(&nal.gb, 5);
  
  
  
          switch (nal.type) {
  
          case H264_NAL_SPS:
  
              ff_h264_decode_seq_parameter_set(&nal.gb, avctx, &p->ps);
  
              break;
  
          case H264_NAL_PPS:
  
              ff_h264_decode_picture_parameter_set(&nal.gb, avctx, &p->ps,
  
                                                   nal.size_bits);
  
              break;
  
          case H264_NAL_SEI:
  
              ff_h264_sei_decode(&p->sei, &nal.gb, &p->ps, avctx);
  
              break;
  
          case H264_NAL_IDR_SLICE:
  
              s->key_frame = 1;
  
  
  
              p->poc.prev_frame_num        = 0;
  
              p->poc.prev_frame_num_offset = 0;
  
              p->poc.prev_poc_msb          =
  
              p->poc.prev_poc_lsb          = 0;
  
          /* fall through */
  
          case H264_NAL_SLICE:
  
              get_ue_golomb(&nal.gb);  // skip first_mb_in_slice
  
              slice_type   = get_ue_golomb_31(&nal.gb);
  
              s->pict_type = ff_h264_golomb_to_pict_type[slice_type % 5];
  
              if (p->sei.recovery_point.recovery_frame_cnt >= 0) {
  
                  /* key frame, since recovery_frame_cnt is set */
  
                  s->key_frame = 1;
  
              }
  
              pps_id = get_ue_golomb(&nal.gb);
  
              if (pps_id >= MAX_PPS_COUNT) {
  
                  av_log(avctx, AV_LOG_ERROR,
  
                         "pps_id %u out of range\n", pps_id);
  
                  goto fail;
  
              }
  
              if (!p->ps.pps_list[pps_id]) {
  
                  av_log(avctx, AV_LOG_ERROR,
  
                         "non-existing PPS %u referenced\n", pps_id);
  
                  goto fail;
  
              }
  
              p->ps.pps = (const PPS*)p->ps.pps_list[pps_id]->data;
  
              if (!p->ps.sps_list[p->ps.pps->sps_id]) {
  
                  av_log(avctx, AV_LOG_ERROR,
  
                         "non-existing SPS %u referenced\n", p->ps.pps->sps_id);
  
                  goto fail;
  
              }
  
              p->ps.sps = (SPS*)p->ps.sps_list[p->ps.pps->sps_id]->data;
  
  
  
              sps = p->ps.sps;
  
  
  
              p->poc.frame_num = get_bits(&nal.gb, sps->log2_max_frame_num);
  
  
  
              s->coded_width  = 16 * sps->mb_width;
  
              s->coded_height = 16 * sps->mb_height;
  
              s->width        = s->coded_width  - (sps->crop_right + sps->crop_left);
  
              s->height       = s->coded_height - (sps->crop_top   + sps->crop_bottom);
  
              if (s->width <= 0 || s->height <= 0) {
  
                  s->width  = s->coded_width;
  
                  s->height = s->coded_height;
  
              }
  
  
  
              switch (sps->bit_depth_luma) {
  
              case 9:
  
                  if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P9;
  
                  else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P9;
  
                  else                                  s->format = AV_PIX_FMT_YUV420P9;
  
                  break;
  
              case 10:
  
                  if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P10;
  
                  else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P10;
  
                  else                                  s->format = AV_PIX_FMT_YUV420P10;
  
                  break;
  
              case 8:
  
                  if (sps->chroma_format_idc == 3)      s->format = AV_PIX_FMT_YUV444P;
  
                  else if (sps->chroma_format_idc == 2) s->format = AV_PIX_FMT_YUV422P;
  
                  else                                  s->format = AV_PIX_FMT_YUV420P;
  
                  break;
  
              default:
  
                  s->format = AV_PIX_FMT_NONE;
  
              }
  
  
  
              avctx->profile = ff_h264_get_profile(sps);
  
              avctx->level   = sps->level_idc;
  
  
  
              if (sps->frame_mbs_only_flag) {
  
                  p->picture_structure = PICT_FRAME;
  
              } else {
  
                  if (get_bits1(&nal.gb)) { // field_pic_flag
  
                      p->picture_structure = PICT_TOP_FIELD + get_bits1(&nal.gb); // bottom_field_flag
  
                  } else {
  
                      p->picture_structure = PICT_FRAME;
  
                  }
  
              }
  
  
  
              if (nal.type == H264_NAL_IDR_SLICE)
  
                  get_ue_golomb(&nal.gb); /* idr_pic_id */
  
              if (sps->poc_type == 0) {
  
                  p->poc.poc_lsb = get_bits(&nal.gb, sps->log2_max_poc_lsb);
  
  
  
                  if (p->ps.pps->pic_order_present == 1 &&
  
                      p->picture_structure == PICT_FRAME)
  
                      p->poc.delta_poc_bottom = get_se_golomb(&nal.gb);
  
              }
  
  
  
              if (sps->poc_type == 1 &&
  
                  !sps->delta_pic_order_always_zero_flag) {
  
                  p->poc.delta_poc[0] = get_se_golomb(&nal.gb);
  
  
  
                  if (p->ps.pps->pic_order_present == 1 &&
  
                      p->picture_structure == PICT_FRAME)
  
                      p->poc.delta_poc[1] = get_se_golomb(&nal.gb);
  
              }
  
  
  
              /* Decode POC of this picture.
  
               * The prev_ values needed for decoding POC of the next picture are not set here. */
  
              field_poc[0] = field_poc[1] = INT_MAX;
  
              ff_h264_init_poc(field_poc, &s->output_picture_number, sps,
  
                               &p->poc, p->picture_structure, nal.ref_idc);
  
  
  
              /* Continue parsing to check if MMCO_RESET is present.
  
               * FIXME: MMCO_RESET could appear in non-first slice.
  
               *        Maybe, we should parse all undisposable non-IDR slice of this
  
               *        picture until encountering MMCO_RESET in a slice of it. */
  
              if (nal.ref_idc && nal.type != H264_NAL_IDR_SLICE) {
  
                  got_reset = scan_mmco_reset(s, &nal.gb, avctx);
  
                  if (got_reset < 0)
  
                      goto fail;
  
              }
  
  
  
              /* Set up the prev_ values for decoding POC of the next picture. */
  
              p->poc.prev_frame_num        = got_reset ? 0 : p->poc.frame_num;
  
              p->poc.prev_frame_num_offset = got_reset ? 0 : p->poc.frame_num_offset;
  
              if (nal.ref_idc != 0) {
  
                  if (!got_reset) {
  
                      p->poc.prev_poc_msb = p->poc.poc_msb;
  
                      p->poc.prev_poc_lsb = p->poc.poc_lsb;
  
                  } else {
  
                      p->poc.prev_poc_msb = 0;
  
                      p->poc.prev_poc_lsb =
  
                          p->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
  
                  }
  
              }
  
  
  
              if (sps->pic_struct_present_flag) {
  
                  switch (p->sei.picture_timing.pic_struct) {
  
                  case SEI_PIC_STRUCT_TOP_FIELD:
  
                  case SEI_PIC_STRUCT_BOTTOM_FIELD:
  
                      s->repeat_pict = 0;
  
                      break;
  
                  case SEI_PIC_STRUCT_FRAME:
  
                  case SEI_PIC_STRUCT_TOP_BOTTOM:
  
                  case SEI_PIC_STRUCT_BOTTOM_TOP:
  
                      s->repeat_pict = 1;
  
                      break;
  
                  case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
  
                  case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
  
                      s->repeat_pict = 2;
  
                      break;
  
                  case SEI_PIC_STRUCT_FRAME_DOUBLING:
  
                      s->repeat_pict = 3;
  
                      break;
  
                  case SEI_PIC_STRUCT_FRAME_TRIPLING:
  
                      s->repeat_pict = 5;
  
                      break;
  
                  default:
  
                      s->repeat_pict = p->picture_structure == PICT_FRAME ? 1 : 0;
  
                      break;
  
                  }
  
              } else {
  
                  s->repeat_pict = p->picture_structure == PICT_FRAME ? 1 : 0;
  
              }
  
  
  
              if (p->picture_structure == PICT_FRAME) {
  
                  s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
  
                  if (sps->pic_struct_present_flag) {
  
                      switch (p->sei.picture_timing.pic_struct) {
  
                      case SEI_PIC_STRUCT_TOP_BOTTOM:
  
                      case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
  
                          s->field_order = AV_FIELD_TT;
  
                          break;
  
                      case SEI_PIC_STRUCT_BOTTOM_TOP:
  
                      case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
  
                          s->field_order = AV_FIELD_BB;
  
                          break;
  
                      default:
  
                          s->field_order = AV_FIELD_PROGRESSIVE;
  
                          break;
  
                      }
  
                  } else {
  
                      if (field_poc[0] < field_poc[1])
  
                          s->field_order = AV_FIELD_TT;
  
                      else if (field_poc[0] > field_poc[1])
  
                          s->field_order = AV_FIELD_BB;
  
                      else
  
                          s->field_order = AV_FIELD_PROGRESSIVE;
  
                  }
  
              } else {
  
                  if (p->picture_structure == PICT_TOP_FIELD)
  
                      s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
  
                  else
  
                      s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
  
                  s->field_order = AV_FIELD_UNKNOWN;
  
              }
  
  
  
              av_freep(&nal.rbsp_buffer);
  
              return 0; /* no need to evaluate the rest */
  
          }
  
          buf += consumed;
  
      }
  
      /* didn't find a picture! */
  
      av_log(avctx, AV_LOG_ERROR, "missing picture in access unit\n");
  
  fail:
  
      av_freep(&nal.rbsp_buffer);
  
      return -1;
  
  }
  