stereo3d: initialize AVStereo3D to zero

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavutil/stereo3d.c

@@ -19,6 +19,7 @@
  */
 
 #include <stdint.h>
+#include <string.h>
 
 #include "mem.h"
 #include "stereo3d.h"
@@ -36,5 +37,7 @@ AVStereo3D *av_stereo3d_create_side_data(AVFrame *frame)
     if (!side_data)
         return NULL;
 
+    memset(side_data->data, 0, sizeof(AVStereo3D));
+
     return (AVStereo3D *)side_data->data;
 }