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ffmpeg-4.2.2/libavdevice/sndio_dec.c 3.37 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * sndio play and grab interface
   * Copyright (c) 2010 Jacob Meuser
   *
   * 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 <stdint.h>
  #include <sndio.h>
  
  #include "libavutil/internal.h"
  #include "libavutil/opt.h"
  #include "libavutil/time.h"
  
  #include "libavformat/avformat.h"
  #include "libavformat/internal.h"
  
  #include "libavdevice/sndio.h"
  
  static av_cold int audio_read_header(AVFormatContext *s1)
  {
      SndioData *s = s1->priv_data;
      AVStream *st;
      int ret;
  
      st = avformat_new_stream(s1, NULL);
      if (!st)
          return AVERROR(ENOMEM);
  
      ret = ff_sndio_open(s1, 0, s1->url);
      if (ret < 0)
          return ret;
  
      /* take real parameters */
      st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
      st->codecpar->codec_id    = s->codec_id;
      st->codecpar->sample_rate = s->sample_rate;
      st->codecpar->channels    = s->channels;
  
      avpriv_set_pts_info(st, 64, 1, 1000000);  /* 64 bits pts in us */
  
      return 0;
  }
  
  static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
  {
      SndioData *s = s1->priv_data;
      int64_t bdelay, cur_time;
      int ret;
  
      if ((ret = av_new_packet(pkt, s->buffer_size)) < 0)
          return ret;
  
      ret = sio_read(s->hdl, pkt->data, pkt->size);
      if (ret == 0 || sio_eof(s->hdl)) {
          av_packet_unref(pkt);
          return AVERROR_EOF;
      }
  
      pkt->size   = ret;
      s->softpos += ret;
  
      /* compute pts of the start of the packet */
      cur_time = av_gettime();
  
      bdelay = ret + s->hwpos - s->softpos;
  
      /* convert to pts */
      pkt->pts = cur_time - ((bdelay * 1000000) /
          (s->bps * s->channels * s->sample_rate));
  
      return 0;
  }
  
  static av_cold int audio_read_close(AVFormatContext *s1)
  {
      SndioData *s = s1->priv_data;
  
      ff_sndio_close(s);
  
      return 0;
  }
  
  static const AVOption options[] = {
      { "sample_rate", "", offsetof(SndioData, sample_rate), AV_OPT_TYPE_INT, {.i64 = 48000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
      { "channels",    "", offsetof(SndioData, channels),    AV_OPT_TYPE_INT, {.i64 = 2},     1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
      { NULL },
  };
  
  static const AVClass sndio_demuxer_class = {
      .class_name     = "sndio indev",
      .item_name      = av_default_item_name,
      .option         = options,
      .version        = LIBAVUTIL_VERSION_INT,
      .category       = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
  };
  
  AVInputFormat ff_sndio_demuxer = {
      .name           = "sndio",
      .long_name      = NULL_IF_CONFIG_SMALL("sndio audio capture"),
      .priv_data_size = sizeof(SndioData),
      .read_header    = audio_read_header,
      .read_packet    = audio_read_packet,
      .read_close     = audio_read_close,
      .flags          = AVFMT_NOFILE,
      .priv_class     = &sndio_demuxer_class,
  };