Bug 22593 – <video> pixel tests are failing if display is asleep

• Status: RESOLVED
• Resolution: WONTFIX
• Component: Tools / Tests

[Pierre-Olivier Latour]

<video> pixel tests are randomly failing on bots (actually, they are failing more often than passing): when failing, the failure is apparently always the same: it's a different in brightness

Fail: http://build.webkit.org/results/trunk-mac-intel-pixel/665/results.html
Pass: http://build.webkit.org/results/trunk-mac-intel-pixel/664/results.html
Fail: http://build.webkit.org/results/trunk-mac-intel-pixel/663/results.html

[Pierre-Olivier Latour]

Doesn't seem to repro on the Tiger bot: there it's always the same 2 tests that fail.

I can't repro the random failure on my machine which is very similar to the Leopard bot, so I took offline the bot to attempt to repro there, but still can't after several attempts (either when running LayoutTests/media or the entire LayoutTests). There must be something different the build bot does...

For reference, the expected RGB value of the top-left pixel of the first video when the display is using the GenericRGB profile for the LayoutTests/media/video-aspect-ratio.html test is 60-23-87.

[Pierre-Olivier Latour]

Actually, I spoke too fast: I cannot repro the failures on the Tiger bot and these failures are also brightness related, so I guess it's the same bug. The difference is that on the Leopard bot it happens now and then, while on Tiger all the time:

media/video-aspect-ratio.html	expected image	image diffs	2.05%
media/video-controls-rendering.html	expected image	image diffs	1.68%

http://build.webkit.org/builders/trunk-mac-ppc-pixel

[Pierre-Olivier Latour]

I finally found the cause: the video frame in the <video> layout tests only renders with a different brightness when the display of the computer is asleep!

Tiger 10.4.11 & Leopard 10.5.5 are apparently affected when using QT 7.5.5.

I don't know however it's specific to this H264 video used by the tests or a generic <video> issue.

I don't think it's worth tracking down as it's potentially quite a bit of work for a limited return: only test system are affected as nobody would want to watch a video with the display asleep.