1084070 - Frame rate stuttering when screen refresh rate is more than 60 Hz and OMTC enabled

Status: UNCONFIRMED

(Core :: Graphics, defect)

Description

[woroof]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0
Build ID: 20141011015303

Steps to reproduce:

1. Set screen refresh rate to be MORE than 60Hz, e.g. set 75Hz
2. Make sure layers.offmainthreadcomposition.enabled is true in about:config
3. Open the following URL and verify the smoothness of motion:
http://www.testufo.com/#test=photo&photo=toronto-map.png&pps=960&pursuit=0&height=0


Actual results:

Motion stutters and seems jerky.
The simulation of such motion can be seen here:
http://www.testufo.com/#test=stutter


Expected results:

Motion is smooth.

Comment 1

[woroof]

Notes:

1. The issue affects not only the URL above, but all other animations, like scrolling on other web pages, animated content, etc.

2. The issue works fine, when:
 - layers.offmainthreadcomposition.enabled is false.
 - monitor refresh rate is 60Hz or less (tried only 56Hz).

3. The issue was tested using different refresh rates of the screen in a range from 56Hz to 120Hz, and is reproducible for everything that is more than 60Hz.

4. Reproduced on the following:
 - GPUs: AMD HD4850, Intel HD 4600 - all with latest drivers
 - OSs: Windows 7 x64, Windows 8.1 x64
 - Monitors: 75Hz LCD, old CRT with up to 120Hz

Comment 2

[woroof]

5. This was tested with fresh profile.

6. Because OMTC was enabled by default in Windows in Firefox 33.0, this was working fine in 32.0.3 with default settings. 

7. The issue is reproducible in 32.0.3 if OMTC is enabled.

Comment 3

[Loic]

Could type about:support and paste the "graphics" section, please.

Comment 4

[woroof]

Please find about:support output below:

Adapter Description	ATI Radeon HD 4800 Series
Adapter Drivers	aticfx64 aticfx64 aticfx64 aticfx32 aticfx32 aticfx32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64
Adapter RAM	512
Device ID	0x9442
Direct2D Enabled	true
DirectWrite Enabled	true (6.2.9200.16571)
Driver Date	4-29-2013
Driver Version	8.970.100.1100
GPU #2 Active	false
GPU Accelerated Windows	1/1 Direct3D 11 (OMTC)
Vendor ID	0x1002
WebGL Renderer	Google Inc. -- ANGLE (ATI Radeon HD 4800 Series Direct3D9Ex vs_3_0 ps_3_0)
windowLayerManagerRemote	true
AzureCanvasBackend	direct2d
AzureContentBackend	direct2d
AzureFallbackCanvasBackend	cairo
AzureSkiaAccelerated	0