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ffmpeg-4.2.2/libavcodec/aac_parser.c 2.19 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Audio and Video frame extraction
   * Copyright (c) 2003 Fabrice Bellard
   * Copyright (c) 2003 Michael Niedermayer
   *
   * 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"
  #include "aac_ac3_parser.h"
  #include "adts_header.h"
  #include "adts_parser.h"
  #include "get_bits.h"
  #include "mpeg4audio.h"
  
  static int aac_sync(uint64_t state, AACAC3ParseContext *hdr_info,
          int *need_next_header, int *new_frame_start)
  {
      GetBitContext bits;
      AACADTSHeaderInfo hdr;
      int size;
      union {
          uint64_t u64;
          uint8_t  u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
      } tmp;
  
      tmp.u64 = av_be2ne64(state);
      init_get_bits(&bits, tmp.u8 + 8 - AV_AAC_ADTS_HEADER_SIZE,
                    AV_AAC_ADTS_HEADER_SIZE * 8);
  
      if ((size = ff_adts_header_parse(&bits, &hdr)) < 0)
          return 0;
      *need_next_header = 0;
      *new_frame_start  = 1;
      hdr_info->sample_rate = hdr.sample_rate;
      hdr_info->channels    = ff_mpeg4audio_channels[hdr.chan_config];
      hdr_info->samples     = hdr.samples;
      hdr_info->bit_rate    = hdr.bit_rate;
      return size;
  }
  
  static av_cold int aac_parse_init(AVCodecParserContext *s1)
  {
      AACAC3ParseContext *s = s1->priv_data;
      s->header_size = AV_AAC_ADTS_HEADER_SIZE;
      s->sync = aac_sync;
      return 0;
  }
  
  
  AVCodecParser ff_aac_parser = {
      .codec_ids      = { AV_CODEC_ID_AAC },
      .priv_data_size = sizeof(AACAC3ParseContext),
      .parser_init    = aac_parse_init,
      .parser_parse   = ff_aac_ac3_parse,
      .parser_close   = ff_parse_close,
  };