Function opus_decode_init

libavcodec/opus/dec.c:681–756

}

static av_cold int opus_decode_init(AVCodecContext *avctx)
{
    OpusContext *c = avctx->priv_data;
    int ret;

    avctx->sample_fmt  = AV_SAMPLE_FMT_FLTP;
    avctx->sample_rate = 48000;

    c->fdsp = avpriv_float_dsp_alloc(0);
    if (!c->fdsp)
        return AVERROR(ENOMEM);

    /* find out the channel configuration */
    ret = ff_opus_parse_extradata(avctx, &c->p);
    if (ret < 0)
        return ret;
    if (c->p.gain_i)
        c->gain = ff_exp10(c->p.gain_i / (20.0 * 256));

    /* allocate and init each independent decoder */
    c->streams = av_calloc(c->p.nb_streams, sizeof(*c->streams));
    if (!c->streams) {
        c->p.nb_streams = 0;
        return AVERROR(ENOMEM);
    }

    for (int i = 0; i < c->p.nb_streams; i++) {
        OpusStreamContext *s = &c->streams[i];
        AVChannelLayout layout;

        s->output_channels = (i < c->p.nb_stereo_streams) ? 2 : 1;

        s->avctx = avctx;

        for (int j = 0; j < s->output_channels; j++) {
            s->silk_output[j]       = s->silk_buf[j];
            s->celt_output[j]       = s->celt_buf[j];
            s->redundancy_output[j] = s->redundancy_buf[j];
        }

        s->fdsp = c->fdsp;

        s->swr =swr_alloc();
        if (!s->swr)
            return AVERROR(ENOMEM);

        layout = (s->output_channels == 1) ? (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO :
                                             (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
        av_opt_set_int(s->swr, "in_sample_fmt",      avctx->sample_fmt,  0);
        av_opt_set_int(s->swr, "out_sample_fmt",     avctx->sample_fmt,  0);
        av_opt_set_chlayout(s->swr, "in_chlayout",   &layout,            0);
        av_opt_set_chlayout(s->swr, "out_chlayout",  &layout,            0);
        av_opt_set_int(s->swr, "out_sample_rate",    avctx->sample_rate, 0);
        av_opt_set_int(s->swr, "filter_size",        16,                 0);

        ret = ff_silk_init(avctx, &s->silk, s->output_channels);
        if (ret < 0)
            return ret;