MP4/MOVと大きなtimebase(tbn)

// static int mov_init(AVFormatContext *s)
 f (mov->video_track_timescale) {
    track->timescale = mov->video_track_timescale;
    if (mov->mode == MODE_ISM && mov->video_track_timescale != 10000000)
        av_log(s, AV_LOG_WARNING, "Warning: some tools, like mp4split, assume a timescale of 10000000 for ISMV.\n");
} else {
    track->timescale = st->time_base.den;
    while(track->timescale < 10000)
        track->timescale *= 2;
}