Bug 1818685 - Disable video overlay if mVideoSwapChain->Present() is very slow on Windows r=gfx-reviewers,lsalzman

There were cases that mVideoSwapChain->Present() took long time. It caused low fps and stuttering and lots of dropped frames. When it happens, disabling video overlay could address the problem.

Differential Revision: https://phabricator.services.mozilla.com/D171039

gfx/webrender_bindings/DCLayerTree.cpp

@@ -1099,13 +1099,37 @@ void DCSurfaceVideo::PresentVideo() {
     return;
   }
 
-  HRESULT hr;
-  hr = mVideoSwapChain->Present(0, 0);
+  auto start = TimeStamp::Now();
+  HRESULT hr = mVideoSwapChain->Present(0, 0);
+  auto end = TimeStamp::Now();
+
   if (FAILED(hr) && hr != DXGI_STATUS_OCCLUDED) {
     gfxCriticalNoteOnce << "video Present failed: " << gfx::hexa(hr);
   }
 
   mPrevTexture = mRenderTextureHost;
+
+  // Disable video overlay if mVideoSwapChain->Present() is too slow. It drops
+  // fps.
+
+  if (!StaticPrefs::gfx_webrender_dcomp_video_check_slow_present()) {
+    return;
+  }
+
+  const auto maxWaitDurationMs = 2.0;
+  const auto maxSlowPresentCount = 5;
+  const auto duration = (end - start).ToMilliseconds();
+
+  if (duration > maxWaitDurationMs) {
+    mSlowPresentCount++;
+  } else {
+    mSlowPresentCount = 0;
+  }
+
+  if (mSlowPresentCount > maxSlowPresentCount) {
+    gfxCriticalNoteOnce << "Video swapchain present is slow";
+    RenderThread::Get()->HandleWebRenderError(WebRenderError::VIDEO_OVERLAY);
+  }
 }
 
 DXGI_FORMAT DCSurfaceVideo::GetSwapChainFormat() {

gfx/webrender_bindings/DCLayerTree.h

@@ -353,6 +353,7 @@ class DCSurfaceVideo : public DCSurface {
   bool mFailedYuvSwapChain = false;
   RefPtr<RenderTextureHost> mRenderTextureHost;
   RefPtr<RenderTextureHost> mPrevTexture;
+  int mSlowPresentCount = 0;
 };
 
 /**

modules/libpref/init/StaticPrefList.yaml

@@ -6528,6 +6528,10 @@
     type: bool
     value: @IS_EARLY_BETA_OR_EARLIER@
     mirror: once
+-   name: gfx.webrender.dcomp-video-check-slow-present
+    type: RelaxedAtomicBool
+    value: true
+    mirror: always
 -   name: gfx.video.convert-i420-to-nv12.force-enabled
     type: bool
     value: false