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ffmpeg-4.2.2/libavformat/boadec.c 2.59 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Black ops audio demuxer
   * Copyright (c) 2013 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 "libavutil/intreadwrite.h"
  #include "libavcodec/internal.h"
  #include "avformat.h"
  #include "internal.h"
  
  static int probe(const AVProbeData *p)
  {
      if (p->buf_size < 2096)
          return 0;
      if (   AV_RL32(p->buf     ) != 1
          || AV_RL32(p->buf +  8) > 100000
          || AV_RL32(p->buf + 12) > 8
          || AV_RL32(p->buf + 16) != 2096
          ||!AV_RL32(p->buf + 21)
          || AV_RL16(p->buf + 25) != 2096
          || AV_RL32(p->buf + 48) % AV_RL32(p->buf + 21)
          )
          return 0;
      return AVPROBE_SCORE_EXTENSION;
  }
  
  
  static int read_header(AVFormatContext *s)
  {
      AVStream *st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
  
      st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
      st->codecpar->codec_id = AV_CODEC_ID_ADPCM_MS;
  
      avio_rl32(s->pb);
      avio_rl32(s->pb);
      st->codecpar->sample_rate = avio_rl32(s->pb);
      st->codecpar->channels    = avio_rl32(s->pb);
      if (st->codecpar->channels > FF_SANE_NB_CHANNELS)
          return AVERROR(ENOSYS);
      s->internal->data_offset = avio_rl32(s->pb);
      avio_r8(s->pb);
      st->codecpar->block_align = avio_rl32(s->pb);
      if (st->codecpar->block_align > INT_MAX / FF_SANE_NB_CHANNELS)
          return AVERROR_INVALIDDATA;
      st->codecpar->block_align *= st->codecpar->channels;
  
      avio_seek(s->pb, s->internal->data_offset, SEEK_SET);
  
      return 0;
  }
  
  static int read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVStream *st = s->streams[0];
  
      return av_get_packet(s->pb, pkt, st->codecpar->block_align);
  }
  
  AVInputFormat ff_boa_demuxer = {
      .name           = "boa",
      .long_name      = NULL_IF_CONFIG_SMALL("Black Ops Audio"),
      .read_probe     = probe,
      .read_header    = read_header,
      .read_packet    = read_packet,
      .flags          = AVFMT_GENERIC_INDEX,
  };