Fix bug 837: realloc mode info buffers on resize

The test to determine if the mode info buffers need
to be resized when the frame size changes was
incorrect, as per bug 837.

By storing the size of the allocated data structure,
a simple test determines whether to allocate more
memory when the frame size changes.

Change-Id: I1544698f2882cf958fc672485614f2f46e9719bd

1 files changed, 6 insertions, 8 deletions

diff --git a/vp9/decoder/vp9_decodeframe.c b/vp9/decoder/vp9_decodeframe.c
index 07971687c..a0fff458c 100644
--- a/vp9/decoder/vp9_decodeframe.c
+++ b/vp9/decoder/vp9_decodeframe.c
@@ -627,16 +627,14 @@ static void resize_context_buffers(VP9_COMMON *cm, int width, int height) {
                        "Width and height beyond allowed size.");
 #endif
   if (cm->width != width || cm->height != height) {
-    const int aligned_width = ALIGN_POWER_OF_TWO(width, MI_SIZE_LOG2);
-    const int aligned_height = ALIGN_POWER_OF_TWO(height, MI_SIZE_LOG2);
-
-    // Change in frame size (assumption: color format does not change).
-    if (cm->width == 0 || cm->height == 0 ||
-        aligned_width > cm->width ||
-        aligned_width * aligned_height > cm->width * cm->height) {
+    const int new_rows = ALIGN_POWER_OF_TWO(height,
+                                            MI_SIZE_LOG2) >> MI_SIZE_LOG2;
+    const int new_cols = ALIGN_POWER_OF_TWO(width,
+                                            MI_SIZE_LOG2) >> MI_SIZE_LOG2;
+    if (calc_mi_size(new_rows) * calc_mi_size(new_cols) > cm->mi_alloc_size) {
       if (vp9_alloc_context_buffers(cm, width, height))
         vpx_internal_error(&cm->error, VPX_CODEC_MEM_ERROR,
-                           "Failed to allocate frame buffers");
+                           "Failed to allocate context buffers");
     } else {
       vp9_set_mb_mi(cm, width, height);
     }