OSC sync back

apps/LoopThroughWithOpenGLCompositing/gl/pipeline/OpenGLVideoIOBridge.cpp

@@ -65,7 +65,10 @@ void OpenGLVideoIOBridge::VideoFrameArrived(const VideoIOFrame& inputFrame)
 
 	const long textureSize = inputFrame.rowBytes * static_cast<long>(inputFrame.height);
 
-	EnterCriticalSection(&mMutex);
+	// Never let input upload stall the playout/render callback. If the GL bridge
+	// is busy producing an output frame, skip this upload and use the next input.
+	if (!TryEnterCriticalSection(&mMutex))
+		return;
 
 	wglMakeCurrent(mHdc, mHglrc);		// make OpenGL context current in this thread
 
@@ -93,32 +96,29 @@ void OpenGLVideoIOBridge::PlayoutFrameCompleted(const VideoIOCompletion& complet
 {
 	RecordFramePacing(completion.result);
 
-	EnterCriticalSection(&mMutex);
-
 	VideoIOOutputFrame outputFrame;
 	if (!mVideoIO.BeginOutputFrame(outputFrame))
-	{
-		LeaveCriticalSection(&mMutex);
 		return;
-	}
 	const VideoIOState& state = mVideoIO.State();
 	RenderPipelineFrameContext frameContext;
 	frameContext.videoState = state;
 	frameContext.completion = completion;
 
+	EnterCriticalSection(&mMutex);
+
 	// make GL context current in this thread
 	wglMakeCurrent(mHdc, mHglrc);
 
 	mRenderPipeline.RenderFrame(frameContext, outputFrame);
+	wglMakeCurrent(NULL, NULL);
+
+	LeaveCriticalSection(&mMutex);
 
 	mVideoIO.EndOutputFrame(outputFrame);
 
 	mVideoIO.AccountForCompletionResult(completion.result);
 
-	// Schedule the next frame for playout
+	// Schedule the next frame for playout after the GL bridge is released so
+	// input uploads are not blocked by non-GL output bookkeeping.
 	mVideoIO.ScheduleOutputFrame(outputFrame);
-
-	wglMakeCurrent(NULL, NULL);
-
-	LeaveCriticalSection(&mMutex);
 }