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ffmpeg-4.2.2/libavformat/g726.c 3.35 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * G.726 raw demuxer
   * Copyright 2017 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 "internal.h"
  #include "libavutil/opt.h"
  
  typedef struct G726Context {
      AVClass *class;
      int code_size;
      int sample_rate;
  } G726Context;
  
  static int g726_read_header(AVFormatContext *s)
  {
      G726Context *c = s->priv_data;
      AVStream *st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
  
      st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
      st->codecpar->codec_id   = s->iformat->raw_codec_id;
  
      st->codecpar->sample_rate           = c->sample_rate;
      st->codecpar->bits_per_coded_sample = c->code_size;
      st->codecpar->bit_rate              = ((int[]){ 16000, 24000, 32000, 40000 })[c->code_size - 2];
      st->codecpar->channels              = 1;
  
      return 0;
  }
  
  static int g726_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      int res;
      res = av_get_packet(s->pb, pkt, 1020); // a size similar to RAW_PACKET_SIZE divisible by all code_size values
      if (res < 0)
          return res;
      return 0;
  }
  
  #define OFFSET(x) offsetof(G726Context, x)
  static const AVOption options[] = {
      { "code_size", "Bits per G.726 code",
          OFFSET(code_size),   AV_OPT_TYPE_INT, {.i64 =    4}, 2,       5, AV_OPT_FLAG_DECODING_PARAM },
      { "sample_rate", "",
          OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64 = 8000}, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
      { NULL },
  };
  
  #if CONFIG_G726_DEMUXER
  static const AVClass g726le_demuxer_class = {
      .class_name     = "G.726 big-endian demuxer",
      .item_name      = av_default_item_name,
      .option         = options,
      .version        = LIBAVUTIL_VERSION_INT,
  };
  
  AVInputFormat ff_g726_demuxer = {
      .name           = "g726",
      .long_name      = NULL_IF_CONFIG_SMALL("raw big-endian G.726 (\"left aligned\")"),
      .read_header    = g726_read_header,
      .read_packet    = g726_read_packet,
      .priv_data_size = sizeof(G726Context),
      .priv_class     = &g726le_demuxer_class,
      .raw_codec_id   = AV_CODEC_ID_ADPCM_G726,
  };
  #endif
  
  #if CONFIG_G726LE_DEMUXER
  static const AVClass g726_demuxer_class = {
      .class_name     = "G.726 little-endian demuxer",
      .item_name      = av_default_item_name,
      .option         = options,
      .version        = LIBAVUTIL_VERSION_INT,
  };
  
  AVInputFormat ff_g726le_demuxer = {
      .name           = "g726le",
      .long_name      = NULL_IF_CONFIG_SMALL("raw little-endian G.726 (\"right aligned\")"),
      .read_header    = g726_read_header,
      .read_packet    = g726_read_packet,
      .priv_data_size = sizeof(G726Context),
      .priv_class     = &g726_demuxer_class,
      .raw_codec_id   = AV_CODEC_ID_ADPCM_G726LE,
  };
  #endif