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ffmpeg-4.2.2/libavcodec/eac3_core_bsf.c 2.42 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2018 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
   */
  
  #include "avcodec.h"
  #include "bsf.h"
  #include "get_bits.h"
  #include "ac3_parser_internal.h"
  
  static int eac3_core_filter(AVBSFContext *ctx, AVPacket *pkt)
  {
      AC3HeaderInfo hdr;
      GetBitContext gbc;
      int ret;
  
      ret = ff_bsf_get_packet_ref(ctx, pkt);
      if (ret < 0)
          return ret;
      ret = init_get_bits8(&gbc, pkt->data, pkt->size);
      if (ret < 0)
          goto fail;
  
      ret = ff_ac3_parse_header(&gbc, &hdr);
      if (ret < 0) {
          ret = AVERROR_INVALIDDATA;
          goto fail;
      }
  
      if (hdr.frame_type == EAC3_FRAME_TYPE_INDEPENDENT ||
          hdr.frame_type == EAC3_FRAME_TYPE_AC3_CONVERT) {
          pkt->size = FFMIN(hdr.frame_size, pkt->size);
      } else if (hdr.frame_type == EAC3_FRAME_TYPE_DEPENDENT && pkt->size > hdr.frame_size) {
          AC3HeaderInfo hdr2;
  
          ret = init_get_bits8(&gbc, pkt->data + hdr.frame_size, pkt->size - hdr.frame_size);
          if (ret < 0)
              goto fail;
  
          ret = ff_ac3_parse_header(&gbc, &hdr2);
          if (ret < 0) {
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
  
          if (hdr2.frame_type == EAC3_FRAME_TYPE_INDEPENDENT ||
              hdr2.frame_type == EAC3_FRAME_TYPE_AC3_CONVERT) {
              pkt->size -= hdr.frame_size;
              pkt->data += hdr.frame_size;
          } else {
              pkt->size = 0;
          }
      } else {
          pkt->size = 0;
      }
  
      return 0;
  fail:
      av_packet_unref(pkt);
      return ret;
  }
  
  static const enum AVCodecID codec_ids[] = {
      AV_CODEC_ID_EAC3, AV_CODEC_ID_NONE,
  };
  
  const AVBitStreamFilter ff_eac3_core_bsf = {
      .name      = "eac3_core",
      .filter    = eac3_core_filter,
      .codec_ids = codec_ids,
  };