[FFmpeg-devel] [PATCH]lavfi/decimate: Do not drop first frame

[Carl Eugen Hoyos]

Hi!

Video filter decimate currently (always) drops the first frame 
because its diff values are all 0. Attached patch tries to fix 
ticket #4990.
Better suggestions on how to detect "first frame" welcome.

Please comment, Carl Eugen
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diff --git a/libavfilter/vf_decimate.c b/libavfilter/vf_decimate.c
index cd374c3..55100fc 100644
--- a/libavfilter/vf_decimate.c
+++ b/libavfilter/vf_decimate.c
@@ -177,6 +177,10 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         dm->fid = 0;
 
         /* we have a complete cycle, select the frame to drop */
+        if (!outlink->frame_count) {
+            dm->queue[0].totdiff = dm->scthresh;
+            dm->queue[0].maxbdiff = INT64_MAX;
+        }
         lowest = 0;
         for (i = 0; i < dm->cycle; i++) {
             if (dm->queue[i].totdiff > dm->scthresh)