text: /*
   * AVS2-P2/IEEE1857.4 video parser.
   * Copyright (c) 2018  Huiwen Ren <hwrenx@gmail.com>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "parser.h"
  
  #define AVS2_SLICE_MAX_START_CODE 0x000001AF
  
  #define AVS2_ISPIC(x)  ((x) == 0xB3 || (x) == 0xB6)
  #define AVS2_ISUNIT(x) ((x) == 0xB0 || (x) == 0xB1 || (x) == 0xB2 || AVS2_ISPIC(x))
  
  static int avs2_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
  {
      int pic_found  = pc->frame_start_found;
      uint32_t state = pc->state;
      int cur = 0;
  
      if (!pic_found) {
          for (; cur < buf_size; ++cur) {
              state = (state << 8) | buf[cur];
              if (AVS2_ISUNIT(buf[cur])){
                  cur++;
                  pic_found = 1;
                  break;
              }
          }
      }
  
      if (pic_found) {
          if (!buf_size)
              return END_NOT_FOUND;
          for (; cur < buf_size; cur++) {
              state = (state << 8) | buf[cur];
              if ((state & 0xFFFFFF00) == 0x100 && state > AVS2_SLICE_MAX_START_CODE) {
                  pc->frame_start_found = 0;
                  pc->state = -1;
                  return cur - 3;
              }
          }
      }
  
      pc->frame_start_found = pic_found;
      pc->state = state;
  
      return END_NOT_FOUND;
  }
  
  static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                        const uint8_t **poutbuf, int *poutbuf_size,
                        const uint8_t *buf, int buf_size)
  {
      ParseContext *pc = s->priv_data;
      int next;
  
      if (s->flags & PARSER_FLAG_COMPLETE_FRAMES)  {
          next = buf_size;
      } else {
          next = avs2_find_frame_end(pc, buf, buf_size);
          if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
              *poutbuf = NULL;
              *poutbuf_size = 0;
              return buf_size;
          }
      }
  
      *poutbuf = buf;
      *poutbuf_size = buf_size;
  
      return next;
  }
  
  const AVCodecParser ff_avs2_parser = {
      .codec_ids      = { AV_CODEC_ID_AVS2 },
      .priv_data_size = sizeof(ParseContext),
      .parser_parse   = avs2_parse,
      .parser_close   = ff_parse_close,
  };
  