From 75c09f8d03a1b916df0c4f3b175a0ee7a63f7dd4 Mon Sep 17 00:00:00 2001
From: Vincent Penquerc'h <vincent.penquerch@collabora.co.uk>
Date: Wed, 9 Apr 2014 15:18:22 +0100
Subject: [PATCH] compare: special case empty regions with 1 SSIM to avoid
 dividing by 0

Coverity 1139689, 1139688
---
 gst/debugutils/gstcompare.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gst/debugutils/gstcompare.c b/gst/debugutils/gstcompare.c
index 8fb44a9c2b..5de2f9da36 100644
--- a/gst/debugutils/gstcompare.c
+++ b/gst/debugutils/gstcompare.c
@@ -363,6 +363,10 @@ gst_compare_ssim_window (GstCompare * comp, guint8 * data1, guint8 * data2,
   const gdouble c1 = (k1 * L) * (k1 * L);
   const gdouble c2 = (k2 * L) * (k2 * L);
 
+  /* For empty images, return maximum similarity */
+  if (height <= 0 || width <= 0)
+    return 1.0;
+
   /* plain and simple; no fancy optimizations */
   for (i = 0; i < height; i++) {
     for (j = 0; j < width; j++) {
@@ -414,6 +418,10 @@ gst_compare_ssim_component (GstCompare * comp, guint8 * data1, guint8 * data2,
     }
   }
 
+  /* For empty images, return maximum similarity */
+  if (count == 0)
+    return 1.0;
+
   return (ssim_sum / count);
 }