Function dejitterVideo

libhb/sync.c:876–924

Look for a sequence of packets whose duration as measure by vrate closely matches the duration as measured by timestamp differences. When close matches are found, smooth the timestamps. Most often, video dejitter is applied when there is jitter due to soft telecine. I also have a couple sample files that have very bad video jitter that this corrects.

// soft telecine.  I also have a couple sample files that have very
// bad video jitter that this corrects.
static void dejitterVideo( sync_stream_t * stream )
{
    int           ii, count, jitter_stop;
    double        frame_duration, duration;
    hb_buffer_t * buf;

    count = hb_list_count(stream->in_queue);
    if (count < 2)
    {
        return;
    }

    frame_duration = 90000. * stream->common->job->title->vrate.den /
                              stream->common->job->title->vrate.num;

    // Look for start of jittered sequence
    buf      = hb_list_item(stream->in_queue, 1);
    duration = buf->s.start - stream->next_pts;
    if (ABS(duration - frame_duration) < 1.1)
    {
        // Ignore small jitter
        buf->s.start = stream->next_pts + frame_duration;
        buf = hb_list_item(stream->in_queue, 0);
        buf->s.start = stream->next_pts;
        buf->s.duration = frame_duration;
        buf->s.stop = stream->next_pts + frame_duration;
        return;
    }

    // Look for end of jittered sequence
    jitter_stop = 0;
    for (ii = 1; ii < count; ii++)
    {
        buf      = hb_list_item(stream->in_queue, ii);
        duration = buf->s.start - stream->next_pts;

        // Only dejitter video that aligns periodically
        // with the frame durations.
        if (ABS(duration - ii * frame_duration) < frame_duration / 3)
        {
            jitter_stop = ii;
        }
    }

    if (jitter_stop > 0)
    {
        removeVideoJitter(stream, jitter_stop);
    }
}

// Fix video overlaps that could not be corrected by dejitter
static void fixVideoOverlap( sync_stream_t * stream )