static PayloadContext *
rdt_new_context (void)
{
    PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));

    int ret = avformat_open_input(&rdt->rmctx, "", &ff_rdt_demuxer, NULL);
    if (ret < 0) {
        av_free(rdt);
        return NULL;
    }

    return rdt;
}