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ffmpeg-4.2.2/libavformat/mlpdec.c 2.92 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * MLP and TrueHD demuxer
   * Copyright (c) 2001 Fabrice Bellard
   * Copyright (c) 2005 Alex Beregszaszi
   * Copyright (c) 2015 Carl Eugen Hoyos
   *
   * 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 "avformat.h"
  #include "rawdec.h"
  #include "libavutil/intreadwrite.h"
  
  static int av_always_inline mlp_thd_probe(const AVProbeData *p, uint32_t sync)
  {
      const uint8_t *buf, *last_buf = p->buf, *end = p->buf + p->buf_size;
      int frames = 0, valid = 0, size = 0;
      int nsubframes = 0;
  
      for (buf = p->buf; buf + 8 <= end; buf++) {
          if (AV_RB32(buf + 4) == sync) {
              frames++;
              if (last_buf + size == buf) {
                  valid += 1 + nsubframes / 8;
              }
              nsubframes = 0;
              last_buf = buf;
              size = (AV_RB16(buf) & 0xfff) * 2;
          } else if (buf - last_buf == size) {
              nsubframes++;
              size += (AV_RB16(buf) & 0xfff) * 2;
          }
      }
      if (valid >= 100)
          return AVPROBE_SCORE_MAX;
      return 0;
  }
  
  #if CONFIG_MLP_DEMUXER
  static int mlp_probe(const AVProbeData *p)
  {
      return mlp_thd_probe(p, 0xf8726fbb);
  }
  
  FF_RAW_DEMUXER_CLASS(mlp)
  AVInputFormat ff_mlp_demuxer = {
      .name           = "mlp",
      .long_name      = NULL_IF_CONFIG_SMALL("raw MLP"),
      .read_probe     = mlp_probe,
      .read_header    = ff_raw_audio_read_header,
      .read_packet    = ff_raw_read_partial_packet,
      .flags          = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
      .extensions     = "mlp",
      .raw_codec_id   = AV_CODEC_ID_MLP,
      .priv_data_size = sizeof(FFRawDemuxerContext),
      .priv_class     = &mlp_demuxer_class,
  };
  #endif
  
  #if CONFIG_TRUEHD_DEMUXER
  static int thd_probe(const AVProbeData *p)
  {
      return mlp_thd_probe(p, 0xf8726fba);
  }
  
  FF_RAW_DEMUXER_CLASS(truehd)
  AVInputFormat ff_truehd_demuxer = {
      .name           = "truehd",
      .long_name      = NULL_IF_CONFIG_SMALL("raw TrueHD"),
      .read_probe     = thd_probe,
      .read_header    = ff_raw_audio_read_header,
      .read_packet    = ff_raw_read_partial_packet,
      .flags          = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
      .extensions     = "thd",
      .raw_codec_id   = AV_CODEC_ID_TRUEHD,
      .priv_data_size = sizeof(FFRawDemuxerContext),
      .priv_class     = &truehd_demuxer_class,
  };
  #endif