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3rdparty/ffmpeg-4.4.4/libavcodec/xbm_parser.c 2.71 KB
09c2d08c   Hu Chunming   arm交付版
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  /*
   * XBM 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
   * XBM parser
   */
  
  #include "libavutil/common.h"
  
  #include "parser.h"
  
  typedef struct XBMParseContext {
      ParseContext pc;
      uint16_t state16;
      int count;
  } XBMParseContext;
  
  #define KEY (((uint64_t)'\n' << 56) | ((uint64_t)'#' << 48) | \
               ((uint64_t)'d' << 40)  | ((uint64_t)'e' << 32) | \
               ((uint64_t)'f' << 24) | ('i' << 16) | ('n' << 8) | \
               ('e' << 0))
  
  #define END ((';' << 8) | ('\n' << 0))
  
  static int xbm_init(AVCodecParserContext *s)
  {
      XBMParseContext *bpc = s->priv_data;
  
      bpc->count = 1;
  
      return 0;
  }
  
  static int xbm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
  {
      XBMParseContext *bpc = s->priv_data;
      uint64_t state = bpc->pc.state64;
      uint16_t state16 = bpc->state16;
      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];
          state16 = (state16 << 8) | buf[i];
  
          if (state == KEY)
              bpc->count++;
  
          if ((state == KEY && bpc->count == 1)) {
              next = i - 6;
              break;
          } else if (state16 == END) {
              next = i + 1;
              bpc->count = 0;
              break;
          }
      }
  
      bpc->pc.state64 = state;
      bpc->state16 = state16;
      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_xbm_parser = {
      .codec_ids      = { AV_CODEC_ID_XBM },
      .priv_data_size = sizeof(XBMParseContext),
      .parser_init    = xbm_init,
      .parser_parse   = xbm_parse,
      .parser_close   = ff_parse_close,
  };