commit e8cedfa7ca99824fcf0932bfcef7802af85866e1
author David Barker <david.barker@argondesign.com> Mon Apr 09 14:54:13 2018 +0100
committer Yaowu Xu <yaowu@google.com> Tue Apr 10 15:43:50 2018 +0000
tree 896a9961859c5f37ba693866372c01672664050d
parent 795ba876072ba38318132a8d6bc9cb2bff0c6326

[NORMATIVE] Clear film grain params if !showable

Reset the film grain parameters to all zeros if film grain is
enabled but show_frame and showable_frame are both 0
("unshowable" frames).

This avoids an accidental dependence on the decoding order -
unshowable frames would accidentally keep the film grain parameters
from the previous decoded frame. Note that, even though these
frames don't apply film grain themselves, they can potentially be
used as a source of film grain parameters by future frames.
Thus we still need to reset the parameters to default values.

BUG=aomedia:1730

Change-Id: I445d35e31eb9d264de394a7cc2af151127a5884b

av1/decoder/decodeframe.c

diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index 0ba4410..d8b54e2 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -2168,7 +2168,7 @@
 }
 
 static void read_film_grain(AV1_COMMON *cm, struct aom_read_bit_buffer *rb) {
-  if (cm->film_grain_params_present) {
+  if (cm->film_grain_params_present && (cm->show_frame || cm->showable_frame)) {
     av1_read_film_grain_params(cm, rb);
   } else {
     memset(&cm->film_grain_params, 0, sizeof(cm->film_grain_params));
@@ -3177,9 +3177,7 @@
   if (!frame_is_intra_only(cm)) read_global_motion(cm, rb);
 
   cm->cur_frame->film_grain_params_present = cm->film_grain_params_present;
-  if (cm->show_frame || cm->showable_frame) {
-    read_film_grain(cm, rb);
-  }
+  read_film_grain(cm, rb);
 
   set_single_tile_decoding_mode(&pbi->common);
   return 0;