ost->st = avformat_new_stream(oc, audio.getCodec());
    if (!ost->st) throw std::runtime_error("Could not allocate stream");

    ost->st->id = oc->nb_streams - 1;

    ost->st->time_base = (AVRational){ 1, audio.getSampleRate() };
    ost->st->codec->sample_rate = audio.getSampleRate();
    ost->st->codec->time_base = ost->st->time_base;

    // Some formats want stream headers to be separate.
    if (oc->oformat->flags & AVFMT_GLOBALHEADER) {
        ost->st->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    }

    AVCodecParameters *in_codecpar = audio.getCodecParameters();
    int ret = avcodec_parameters_copy(ost->st->codecpar, in_codecpar);
    if (ret < 0) {
        throw std::runtime_error("Could not copy the stream parameters");
    }

    ost->st->codecpar->codec_tag = 0;

    AVCodecContext *in_ctx = audio.getCodecContext();
    ret = avcodec_copy_context(ost->st->codec, in_ctx);
    if (ret < 0) {
        throw std::runtime_error("Could not copy the codec context");
    }