Remove memset of every external frame buffer.

Libvpx was memseting every external frame buffer before decode. This
was to work around a valgrind issue in our C loop filter. Most of
the time this was not needed and we have noticed some significant
performance loss on some platforms. Now we require the application to
zero out the buffers if it is using external frame buffers.

Change-Id: I7330d00a315e65137ed30edd5f813e8929b76242

test/external_frame_buffer_test.cc

@@ -71,6 +71,7 @@ class ExternalFrameBufferList {
     if (ext_fb_list_[idx].size < min_size) {
       delete [] ext_fb_list_[idx].data;
       ext_fb_list_[idx].data = new uint8_t[min_size];
+      memset(ext_fb_list_[idx].data, 0, min_size);
       ext_fb_list_[idx].size = min_size;
     }
 

vp9/common/vp9_frame_buffers.c

@@ -61,6 +61,10 @@ int vp9_get_frame_buffer(void *cb_priv, size_t min_size,
     if (!int_fb_list->int_fb[i].data)
       return -1;
 
+    // This memset is needed for fixing valgrind error from C loop filter
+    // due to access uninitialized memory in frame border. It could be
+    // removed if border is totally removed.
+    vpx_memset(int_fb_list->int_fb[i].data, 0, min_size);
     int_fb_list->int_fb[i].size = min_size;
   }
 

vpx/vpx_frame_buffer.h

@@ -43,15 +43,15 @@ typedef struct vpx_codec_frame_buffer {
  *
  * This callback is invoked by the decoder to retrieve data for the frame
  * buffer in order for the decode call to complete. The callback must
- * allocate at least min_size in bytes and assign it to fb->data. Then the
- * callback must set fb->size to the allocated size. The application does not
- * need to align the allocated data. The callback is triggered when the
- * decoder needs a frame buffer to decode a compressed image into. This
- * function may be called more than once for every call to vpx_codec_decode.
- * The application may set fb->priv to some data which will be passed
- * back in the ximage and the release function call. |fb| is guaranteed to
- * not be NULL. On success the callback must return 0. Any failure the
- * callback must return a value less than 0.
+ * allocate at least min_size in bytes and assign it to fb->data. The callback
+ * must zero out all the data allocated. Then the callback must set fb->size
+ * to the allocated size. The application does not need to align the allocated
+ * data. The callback is triggered when the decoder needs a frame buffer to
+ * decode a compressed image into. This function may be called more than once
+ * for every call to vpx_codec_decode. The application may set fb->priv to
+ * some data which will be passed back in the ximage and the release function
+ * call. |fb| is guaranteed to not be NULL. On success the callback must
+ * return 0. Any failure the callback must return a value less than 0.
  *
  * \param[in] priv         Callback's private data
  * \param[in] new_size     Size in bytes needed by the buffer

vpx_scale/generic/yv12config.c

@@ -199,11 +199,6 @@ int vp9_realloc_frame_buffer(YV12_BUFFER_CONFIG *ybf,
       if (fb->data == NULL || fb->size < external_frame_size)
         return -1;
 
-      // This memset is needed for fixing valgrind error from C loop filter
-      // due to access uninitialized memory in frame border. It could be
-      // removed if border is totally removed.
-      vpx_memset(fb->data, 0, fb->size);
-
       ybf->buffer_alloc = (uint8_t *)yv12_align_addr(fb->data, 32);
     } else if (frame_size > (size_t)ybf->buffer_alloc_sz) {
       // Allocation to hold larger frame, or first allocation.

vpxdec.c

@@ -384,7 +384,7 @@ int get_vp9_frame_buffer(void *cb_priv, size_t min_size,
 
   if (ext_fb_list->ext_fb[i].size < min_size) {
     free(ext_fb_list->ext_fb[i].data);
-    ext_fb_list->ext_fb[i].data = (uint8_t *)malloc(min_size);
+    ext_fb_list->ext_fb[i].data = (uint8_t *)calloc(min_size, sizeof(uint8_t));
     if (!ext_fb_list->ext_fb[i].data)
       return -1;