Fix detelecine filter for patterns like 3444 or 33333334.

Signed-off-by: Benjamin Steffes <benjaminst123@gmail.com>
Signed-off-by: Carl Eugen Hoyos <cehoyos@ag.or.at>

libavfilter/vf_detelecine.c

@@ -195,11 +195,6 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
         s->nskip_fields -= 2;
         return 0;
     } else if (s->nskip_fields >= 1) {
-        if (s->occupied) {
-            s->occupied = 0;
-            s->nskip_fields--;
-        }
-        else {
         for (i = 0; i < s->nb_planes; i++) {
             av_image_copy_plane(s->temp->data[i], s->temp->linesize[i],
                                 inpicref->data[i], inpicref->linesize[i],
@@ -210,7 +205,6 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
         s->nskip_fields--;
         return 0;
     }
-    }
 
     if (s->nskip_fields == 0) {
         while(!len && s->pattern[s->pattern_pos]) {
@@ -243,7 +237,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
                                     s->stride[i],
                                     (s->planeheight[i] - !s->first_field + 1) / 2);
             }
-            len -= 2;
+
+            s->occupied = 0;
+            if (len <= 2) {
                 for (i = 0; i < s->nb_planes; i++) {
                     av_image_copy_plane(s->temp->data[i], s->temp->linesize[i],
                                         inpicref->data[i], inpicref->linesize[i],
@@ -251,7 +247,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
                                         s->planeheight[i]);
                 }
                 s->occupied = 1;
+            }
             out = 1;
+            len = (len >= 3) ? len - 3 : 0;
         } else {
             if (len >= 2) {
                 // output THIS image as-is