avfilter/vf_interlace: more accurate pts calculation

Signed-off-by: Aleksey Vasenev <margtu-fivt@ya.ru>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/vf_interlace.c

@@ -111,7 +111,6 @@ static int config_out_props(AVFilterLink *outlink)
     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;
 
@@ -204,7 +203,6 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
     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->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER, s->lowpass);