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3rdparty/ffmpeg-4.4.4/libavcodec/cri_parser.c 2.86 KB
09c2d08c   Hu Chunming   arm交付版
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  /*
   * CRI parser
   * Copyright (c) 2021 Paul B Mahol
   *
   * 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
   */
  
  /**
   * @file
   * CRI parser
   */
  
  #include "libavutil/bswap.h"
  #include "libavutil/common.h"
  
  #include "parser.h"
  
  typedef struct CRIParser {
      ParseContext pc;
      int count;
      int chunk;
      int read_bytes;
      int skip_bytes;
  } CRIParser;
  
  #define KEY (((uint64_t)'\1' << 56) | ((uint64_t)'\0' << 48) | \
               ((uint64_t)'\0' << 40) | ((uint64_t)'\0' << 32) | \
               ((uint64_t)'\4' << 24) | ((uint64_t)'\0' << 16) | \
               ((uint64_t)'\0' <<  8) | ((uint64_t)'\0' <<  0))
  
  static int cri_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
  {
      CRIParser *bpc = s->priv_data;
      uint64_t state = bpc->pc.state64;
      int next = END_NOT_FOUND, i = 0;
  
      s->pict_type = AV_PICTURE_TYPE_I;
      s->key_frame = 1;
      s->duration  = 1;
  
      *poutbuf_size = 0;
      *poutbuf = NULL;
  
      for (; i < buf_size; i++) {
          state = (state << 8) | buf[i];
          bpc->read_bytes++;
  
          if (bpc->skip_bytes > 0) {
              bpc->skip_bytes--;
              if (bpc->skip_bytes == 0)
                  bpc->read_bytes = 0;
          } else {
              if (state != KEY)
                  continue;
          }
  
          if (bpc->skip_bytes == 0 && bpc->read_bytes >= 8) {
              bpc->skip_bytes = av_bswap32(state & 0xFFFFFFFF);
              bpc->chunk = state >> 32;
              bpc->read_bytes = 0;
              bpc->count++;
          }
  
          if (bpc->chunk == 0x01000000 && bpc->skip_bytes == 4 &&
              bpc->read_bytes == 0 && bpc->count > 1) {
              next = i - 7;
              break;
          }
      }
  
      bpc->pc.state64 = state;
      if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0) {
          *poutbuf = NULL;
          *poutbuf_size = 0;
          return buf_size;
      }
  
      *poutbuf      = buf;
      *poutbuf_size = buf_size;
  
      return next;
  }
  
  AVCodecParser ff_cri_parser = {
      .codec_ids      = { AV_CODEC_ID_CRI },
      .priv_data_size = sizeof(CRIParser),
      .parser_parse   = cri_parse,
      .parser_close   = ff_parse_close,
  };