func: static OutputStream *new_audio_stream(OptionsContext *o, AVFormatContext *oc)
  
  {
  
      AVStream *st;
  
      OutputStream *ost;
  
      AVCodecContext *audio_enc;
  
  
  
      ost = new_output_stream(o, oc, AVMEDIA_TYPE_AUDIO);
  
      st  = ost->st;
  
  
  
      audio_enc = st->codec;
  
      audio_enc->codec_type = AVMEDIA_TYPE_AUDIO;
  
  
  
      if (!ost->stream_copy) {
  
          char *sample_fmt = NULL;
  
  
  
          MATCH_PER_STREAM_OPT(audio_channels, i, audio_enc->channels, oc, st);
  
  
  
          MATCH_PER_STREAM_OPT(sample_fmts, str, sample_fmt, oc, st);
  
          if (sample_fmt &&
  
              (audio_enc->sample_fmt = av_get_sample_fmt(sample_fmt)) == AV_SAMPLE_FMT_NONE) {
  
              av_log(NULL, AV_LOG_FATAL, "Invalid sample format '%s'\n", sample_fmt);
  
              exit_program(1);
  
          }
  
  
  
          MATCH_PER_STREAM_OPT(audio_sample_rate, i, audio_enc->sample_rate, oc, st);
  
      }
  
  
  
      return ost;
  
  }
  