From dfbf52baac1a270dd18ae18c9f9bd729a780659b Mon Sep 17 00:00:00 2001
From: "mflodman@webrtc.org"
 <mflodman@webrtc.org@4adac7df-926f-26a2-2b94-8c16560cd09d>
Date: Mon, 2 Sep 2013 12:44:57 +0000
Subject: [PATCH] Fixing capture frame race in ViECapturer.

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4654 4adac7df-926f-26a2-2b94-8c16560cd09d
---
 webrtc/video_engine/vie_capturer.cc | 18 +++++++++++-------
 webrtc/video_engine/vie_capturer.h  |  2 ++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/webrtc/video_engine/vie_capturer.cc b/webrtc/video_engine/vie_capturer.cc
index cc08ffaae1..8629a1cd86 100644
--- a/webrtc/video_engine/vie_capturer.cc
+++ b/webrtc/video_engine/vie_capturer.cc
@@ -511,13 +511,7 @@ bool ViECapturer::ViECaptureThreadFunction(void* obj) {
 bool ViECapturer::ViECaptureProcess() {
   if (capture_event_.Wait(kThreadWaitTimeMs) == kEventSignaled) {
     deliver_cs_->Enter();
-    if (!captured_frame_.IsZeroSize()) {
-      // New I420 frame.
-      capture_cs_->Enter();
-      deliver_frame_.SwapFrame(&captured_frame_);
-      captured_frame_.ResetSize();
-      capture_cs_->Leave();
-
+    if (MaybeSwapCapturedToDeliverFrame()) {
       DeliverI420Frame(&deliver_frame_);
     }
     deliver_cs_->Leave();
@@ -652,4 +646,14 @@ void ViECapturer::OnNoPictureAlarm(const int32_t id,
   observer_->NoPictureAlarm(id, vie_alarm);
 }
 
+bool ViECapturer::MaybeSwapCapturedToDeliverFrame() {
+  CriticalSectionScoped cs(capture_cs_.get());
+  if (captured_frame_.IsZeroSize())
+    return false;
+
+  deliver_frame_.SwapFrame(&captured_frame_);
+  captured_frame_.ResetSize();
+  return true;
+}
+
 }  // namespace webrtc
diff --git a/webrtc/video_engine/vie_capturer.h b/webrtc/video_engine/vie_capturer.h
index ff656ffde3..db12a59a84 100644
--- a/webrtc/video_engine/vie_capturer.h
+++ b/webrtc/video_engine/vie_capturer.h
@@ -144,6 +144,8 @@ class ViECapturer
   void DeliverCodedFrame(VideoFrame* video_frame);
 
  private:
+  bool MaybeSwapCapturedToDeliverFrame();
+
   // Never take capture_cs_ before deliver_cs_!
   scoped_ptr<CriticalSectionWrapper> capture_cs_;
   scoped_ptr<CriticalSectionWrapper> deliver_cs_;