outlink->time_base = inlink->time_base;
outlink->frame_rate = inlink->frame_rate;
// half framerate
+ outlink->time_base.num *= 2;
outlink->frame_rate.den *= 2;
outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
av_frame_copy_props(out, s->cur);
out->interlaced_frame = 1;
out->top_field_first = tff;
+ out->pts /= 2; // adjust pts to new framerate
/* copy upper/lower field from cur */
copy_picture_field(s, s->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER, s->lowpass);