Function adjust_frame_rate

libhb/vfr.c:201–352

This section of the code implements video frame rate control. Since filters are allowed to duplicate and drop frames (which changes the timing), this has to be the last thing done in render. There are three options, selected by the value of cfr: 0 - Variable Frame Rate (VFR) or 'same as source': frame times are left alone 1 - Constant Frame Rate (CFR): Frame timings are adjusted so that all frame

//       times are left alone.
//
static hb_buffer_t * adjust_frame_rate( hb_filter_private_t * pv,
                                        hb_buffer_t * in )
{

    if (pv->cfr == 0)
    {
        if (in)
        {
            ++pv->count_frames;
            pv->out_last_stop = in->s.stop;
        }
        return in;
    }

    int count;

    // in == NULL signals we are flushing the frame_rate_list
    if (in != NULL)
    {
        if (pv->out_last_stop == (int64_t)AV_NOPTS_VALUE)
        {
            pv->out_last_stop = in->s.start;
        }

#if defined(HB_DEBUG_CFR_DROPS)
        in->s.pcr = pv->sequence++;
#endif
        hb_list_add(pv->frame_rate_list, in);
        count = hb_list_count(pv->frame_rate_list);
        if (count < 2)
        {
            return NULL;
        }

        hb_buffer_t * penultimate, * ultimate;
        penultimate = hb_list_item(pv->frame_rate_list, count - 2);
        ultimate    = hb_list_item(pv->frame_rate_list, count - 1);

        pv->frame_metric[count - 1] = pv->metric->work(pv->metric, penultimate, ultimate);

        if (count < pv->frame_analysis_depth)
        {
            return NULL;
        }
    }
    else
    {
        count = hb_list_count(pv->frame_rate_list);
    }

    hb_buffer_list_t   list;
    hb_buffer_t      * out;
    double             cfr_stop;
    int                drop_frame;

    hb_buffer_list_clear(&list);

    drop_frame = find_drop_frame(pv, count);