VTVDA: Fix computation of |reorder_window|.

media/video/h264_poc.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 49 matching lines @@
   if (slice_hdr.field_pic_flag) {
     DLOG(ERROR) << "Interlaced frames are not supported";
     return false;
   }
 
   bool mmco5 = HasMMCO5(slice_hdr);
   int32_t max_frame_num = 1 << (sps->log2_max_frame_num_minus4 + 4);
   int32_t max_pic_order_cnt_lsb =
       1 << (sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
 
-  // Check for invalid (including duplicate) |frame_num| values. All cases are
-  // treated as gaps, which is to say that nothing is done. (Gaps don't affect
-  // POC computation.)
-  if (!slice_hdr.idr_pic_flag &&
-      slice_hdr.frame_num != (prev_frame_num_ + 1) % max_frame_num) {
-    if (!sps->gaps_in_frame_num_value_allowed_flag)
-      DLOG(WARNING) << "Invalid gap in frame_num";
-  }
+  // Note: Duplicate frame numbers are ignored. They occur in many videos
+  // despite appearing to be invalid according to the spec.
+  // TODO(sandersd): Check if these videos are using slices or have redundant
+  // streams.
+
+  // Note: Gaps in frame numbers are also ignored. They do not affect POC
+  // computation.
 
   // Based on T-REC-H.264 8.2.1, "Decoding process for picture order
   // count", available from http://www.itu.int/rec/T-REC-H.264.
   //
   // Reorganized slightly from spec pseudocode to handle MMCO5 when storing
   // state instead of when loading it.
   switch (sps->pic_order_cnt_type) {
     case 0: {
       int32_t prev_pic_order_cnt_msb = ref_pic_order_cnt_msb_;
       int32_t prev_pic_order_cnt_lsb = ref_pic_order_cnt_lsb_;
@@ skipping 134 matching lines @@
 
     default:
       DLOG(ERROR) << "Invalid pic_order_cnt_type: " << sps->pic_order_cnt_type;
       return false;
   }
 
   return true;
 }
 
 }  // namespace media