Flash video flickering black in Firefox 36

[percentage]

When I watch Flash videos in Firefox 36, the Flash frame in some cases (see below) flickers black frequently. That is, both the video and video controls are replaced by a black frame briefly (about the time it takes to blink quickly). This happens very frequently (I counted 22 flickers in 10 seconds on a video just now), which makes them basically unwatchable.

I have this problem with, among others, Facebook videos, Twitch.tv streams, and Youtube videos embedded in Tumblr pages. However, there are other sites where the video never flickers at all. For example, Youtube videos (on youtube.com) and Twitch streams viewed from speedrunslive.com. Playing videos in full screen also stops them from flickering.

I have had this problem since immediately after updating to Firefox 36, and never before. I have the latest version of Flash, 16.0.0.305. I've tried resetting my Flash settings without results, and enabling and disabling machine acceleration in Flash makes no difference. I use Flashblock normally, but the problem persists even when I disable it.

I tried to diagnose the problem with Safe Mode as well. Using Safe Mode, I couldn't get Twitch streams to load on twitch.tv at all, though they loaded fine on speedrunslive.com. Maybe that's part of the problem?

I hope someone here knows the cause of this problem. Thanks in advance.

[DanRaisch]

Turn off hardware acceleration in Firefox -- https://support.mozilla.org/en-US/questions/986276

[percentage]

That solves the problem, but causes fonts to render strangely instead (because of a faulty Microsoft update that breaks font rendering in Windows Vista). I'm caught between a rock and a hard place.

I think I prefer flickering video to strange fonts, so I think I'll leave hardware acceleration on. But thanks for helping.

[JayhawksRock]

Have you Not gone back to MS and check for updates... I thought they puplished a fix for that Vista font bug 2 days after the last Windows Update that messed up the Font rendering.

[patrickjdempsey]

Type about:config in the URLbar and press enter. Click through the warning. Double-click on the following entry to set it to true:
gfx.font_rendering.directwrite.enabled

This will force Firefox to use DW font rendering even though other hardware acceleration is disabled. The real problem is that beginning with XP and getting worse with Vista, MicroSoft has completely removed the old "font smoothing" stuff and instead relies entirely on your graphics card for rendering smooth fonts. This is mostly for the befit of crappy LCD monitors that have weird issues rendering fonts. Personally, I miss W2K font smoothing with tube monitors. It just worked.

[percentage]

Have you Not gone back to MS and check for updates... I thought they puplished a fix for that Vista font bug 2 days after the last Windows Update that messed up the Font rendering.

I haven't heard of it, I'll download that update. Thanks.

Type about:config in the URLbar and press enter. Click through the warning. Double-click on the following entry to set it to true:
gfx.font_rendering.directwrite.enabled

This will force Firefox to use DW font rendering even though other hardware acceleration is disabled.

Thanks. This renders websites correctly, but the interface text still looks strange. :/

Another issue with disabling hardware acceleration, I realized now, is that the previously flickering videos stutter instead. It looks better now, but still not as good as it did before the update...

[redwolfe_98]

Have you Not gone back to MS and checked for updates? they puplished a fix for that Vista font bug

as far as i know, the MS "update" that fixes the font problem is not being distributed through "windows update".. you have to download it and install it manually..

here is a webpage with some information about the MS update that fixes the font problem:

https://support.microsoft.com/kb/3037639

p.s. another option is to uninstall the 3013455 update, to fix the font problem..

[JayhawksRock]

Glad its Fixed. Thanks for the extra info...

[jimnms]

I noticed the flickering video too after Firefox updated. I'm on Windows 7 though, not Vista.

[DanRaisch]

Running Vista here and not seeing any flickering at all on Youtube.

[MarkRH]

While I do have flickering with sites that have background images when going back to their tab after a couple minutes (https://bugzilla.mozilla.org/show_bug.cgi?id=1137082) I don't have flickering related to YouTube videos.

Windows 7 Pro 64bit.

[guniu]

Since FF 36 I have a lot of flickering on twitch.tv. Especially when the chat is going fast, basically the faster the chat goes the more flickering there is. But sometimes it can go without a single flicker for even 30 minutes, so I have no idea what triggers it. Initially I thought it was twitches fault, but then I reverted to 35.0.1 and the flickering was gone, so it's definitely Firefox's fault. I hope they know about the issue and can do something about it.

[MarkRH]

I've started noticing the flickering with flash videos since 36.0.1 at places like CNN and FoxsportsGo. :/

[patrickjdempsey]

And did either of you try Safe Mode or disabling hardware acceleration?

[MarkRH]

Well, I tried it with HA off and in safe mode and it didn't do it. Then I turned HA back on and it still didn't do it on CNN.

Hate inconsistent behavior. Either work or don't work LOL. Fonts looks funky with HA off though.