avfilter: check that filter_frame and slice variants are not both used

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/avfilter.c

@@ -409,6 +409,8 @@ AVFilter *avfilter_get_by_name(const char *name)
 
 int avfilter_register(AVFilter *filter)
 {
+    int i;
+
     if (next_registered_avfilter_idx == MAX_REGISTERED_AVFILTERS_NB) {
         av_log(NULL, AV_LOG_ERROR,
                "Maximum number of registered filters %d reached, "
@@ -417,6 +419,12 @@ int avfilter_register(AVFilter *filter)
         return AVERROR(ENOMEM);
     }
 
+    for(i=0; filter->inputs && filter->inputs[i].name; i++) {
+        const AVFilterPad *input = &filter->inputs[i];
+        av_assert0(     !input->filter_frame
+                    || (!input->start_frame && !input->end_frame && !input->draw_slice));
+    }
+
     registered_avfilters[next_registered_avfilter_idx++] = filter;
     return 0;
 }