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;
+  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(

[Sergey Ulanov, 2015/01/13 19:19:42]

nit: you can just call updated_region->AddRect() here. There is no need to store
list of aligned rects in aligned_rects.

[Wez, 2015/01/13 19:29:05]

The idea was to allow AddRects() to do whatever smart optimizations it's capable
of.

In particular how does the current DesktopRegion handle reallocations for
internal structures if you build the region rectangle-by-rectangle?

-        rect.left(), rect.top(), rect.right(), rect.bottom())));
+        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());
 
   // 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));
@@ skipping 63 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