Videos are no longer being hardware accelerated on YouTube. According to the stats for nerds section, the video is an mp4. I am using the latest nightly on Windows 7. Test URL: https://www.youtube.com/watch?v=q8ir8rVl2Z4 Last good revision: 8e5c888d0d89 First bad revision: 1f77b78797d6 Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=8e5c888d0d89&tochange=1f77b78797d6 Last good revision: f8051d507461 First bad revision: de0a5cf8c4f9 Pushlog: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=f8051d507461&tochange=de0a5cf8c4f9 Adapter Description NVIDIA GeForce GTX 660 Adapter Drivers nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM 2048 Asynchronous Pan/Zoom wheel input enabled Device ID 0x11c0 Direct2D Enabled true DirectWrite Enabled true (6.2.9200.17292) Driver Date 6-17-2015 Driver Version 10.18.13.5330 GPU #2 Active false GPU Accelerated Windows 1/1 Direct3D 11 (OMTC) Subsys ID 30693842 Supports Hardware H264 Decoding true Vendor ID 0x10de WebGL Renderer Google Inc. -- ANGLE (NVIDIA GeForce GTX 660 Direct3D11 vs_5_0 ps_5_0) windowLayerManagerRemote true AzureCanvasBackend direct2d 1.1 AzureContentBackend direct2d 1.1 AzureFallbackCanvasBackend cairo AzureSkiaAccelerated 0

Trevor, thanks for isolating the regression window. How do you determine whether Firefox is using the hardware decoder for a particular video? Jean-Yves, does this bug look like a regression from bug 1165772?

Chris, I use the tool GPU-Z[1] to monitior the load on what GPU-Z calls the Video Engine. When the Video Engine usage is at 0%, the hardware video decoder on my GPU is not being utilized. [1] http://www.techpowerup.com/gpuz/

I don't see how that's possible really. None of this code determine if video can be accelerated or not. It could be a consequence however of not using the SharedDecoderManager anymore.

Actually, a consequence with the new MSE would have been the total opposite on what's reported here: you couldn't disable HW acceleration which would be a problem with some GPU returning invalid frames.

I just tested and this seems to be isolated to MSE. If I disable MSE the video in comment 0 gets accelerated on YouTube and if I load the same video locally in a <video> tag without MSE the video gets accelerated.

Don't rely on MediaResource format to detect if HW acceleration can be used or not

[Tracking Requested - why for this release]: Regression

Tracked for 42, as it was a regression and a hit to performance. Nice that it's already fixed by the time we got to tracking it! :)