Add 8 pixels of padding around each rectangle under VP9.

remoting/codec/video_encoder_vpx.cc

 // Copyright 2013 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 "remoting/codec/video_encoder_vpx.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/sys_info.h"
@@ skipping 355 matching lines @@
 }
 
 void VideoEncoderVpx::PrepareImage(const webrtc::DesktopFrame& frame,
                                    webrtc::DesktopRegion* updated_region) {
   if (frame.updated_region().is_empty()) {
     updated_region->Clear();
     return;
   }
 
   // Align the region to macroblocks, to avoid encoding artefacts.
+  // If VP9 is in use then we also pad the rectangles before aligning them, to
+  // avoid edge artefacts.
   // This also ensures that all rectangles have even-aligned top-left, which
   // is required for ConvertRGBToYUVWithRect() to work.
-  std::vector<webrtc::DesktopRect> aligned_rects;
+  updated_region->Clear();
+  int padding = use_vp9_ ? 8 : 0;
   for (webrtc::DesktopRegion::Iterator r(frame.updated_region());
        !r.IsAtEnd(); r.Advance()) {
     const webrtc::DesktopRect& rect = r.rect();
-    aligned_rects.push_back(AlignRect(webrtc::DesktopRect::MakeLTRB(
-        rect.left(), rect.top(), rect.right(), rect.bottom())));
+    updated_region->AddRect(AlignRect(webrtc::DesktopRect::MakeLTRB(
+        rect.left() - padding, rect.top() - padding, rect.right() + padding,
+        rect.bottom() + padding)));
   }
-  DCHECK(!aligned_rects.empty());
-  updated_region->Clear();
-  updated_region->AddRects(&aligned_rects[0], aligned_rects.size());
+  DCHECK(!updated_region->is_empty());
 
   // Clip back to the screen dimensions, in case they're not macroblock aligned.
   // The conversion routines don't require even width & height, so this is safe
   // even if the source dimensions are not even.
   updated_region->IntersectWith(
       webrtc::DesktopRect::MakeWH(image_->w, image_->h));
 
   // Convert the updated region to YUV ready for encoding.
   const uint8* rgb_data = frame.data();
   const int rgb_stride = frame.stride();
@@ skipping 59 matching lines @@
     uint8* map = active_map_.get() + top * active_map_width_;
     for (int y = top; y <= bottom; ++y) {
       for (int x = left; x <= right; ++x)
         map[x] = 1;
       map += active_map_width_;
     }
   }
 }
 
 }  // namespace remoting