static void fix_timescale(MOVContext *c, MOVStreamContext *sc)
{
    if (sc->time_scale <= 0) {
        av_log(c->fc, AV_LOG_WARNING, "stream %d, timescale not set\n", sc->ffindex);
        sc->time_scale = c->time_scale;
        if (sc->time_scale <= 0)
            sc->time_scale = 1;
    }
}