My commit at r14340 was not the right solution. For a monocromatic

frame, there will be only one centroid and it will be impossible to 
find three distinct ones. It is better to just avoid shifting if 
there are not three different centroids.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@14343 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/elbg.c

@@ -306,11 +306,10 @@ static void do_shiftings(elbg_data *elbg)
             if (elbg->utility_inc[elbg->numCB-1] == 0)
                 return;
 
-            idx[2] = get_closest_codebook(elbg, idx[0]);
-            do {
             idx[1] = get_high_utility_cell(elbg);
-            } while (idx[1] == idx[0] || idx[1] == idx[2]);
+            idx[2] = get_closest_codebook(elbg, idx[0]);
 
+            if (idx[1] != idx[0] && idx[1] != idx[2])
                 try_shift_candidate(elbg, idx);
         }
 }