Yonke imikhiqizo Community Forum

(AI written summary of troubleshooting steps taken before making this support thread)

Firefox version: - 152.0.1 Release - 153.0 Nightly

OS: - Windows 11 build 26200

GPU: - NVIDIA GeForce RTX 4070 SUPER

Codec package: - Microsoft HEVC Video Extensions installed from Microsoft Store

Problem

Firefox does not expose HEVC playback support, causing Twitch to disable 1440p streams encoded with HEVC.

The same machine can play the same HEVC Twitch streams in Chrome immediately after installing HEVC Video Extensions.

Expected result

Firefox should report HEVC playback support and allow playback of HEVC streams, as Chrome does on the same system.

Actual result

Firefox reports HEVC as unsupported.

about:support:

codecSupportInfo: H264 SWDEC HWDEC VP9 SWDEC HWDEC VP8 SWDEC HWDEC AV1 SWDEC HWDEC HEVC NONE

Troubleshooting already performed

- Installed Microsoft HEVC Video Extensions - Rebooted Windows - Updated NVIDIA drivers - Verified hardware acceleration is enabled - Tested with a brand new Firefox profile - Tested with Firefox Nightly - Confirmed Chrome can play the same HEVC streams

Additional observations

Chrome: - Twitch 1440p becomes available immediately after installing HEVC Video Extensions - Twitch Stats for Nerds reports:

 hev1.1.6.L150.90.0.0.0.0.0

Firefox: - Twitch reports that the browser does not support the required resolution - 1440p remains greyed out - about:support continues to report HEVC NONE

Reproducible tests

Firefox console:

MediaSource.isTypeSupported('video/mp4; codecs="hev1.1.6.L150.90"')

Result: false

MediaSource.isTypeSupported('video/mp4; codecs="hvc1.1.6.L150.90"')

Result: false

navigator.mediaCapabilities.decodingInfo({

 type: "media-source",
 video: {
   contentType: 'video/mp4; codecs="hev1.1.6.L150.90"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: false,
 smooth: false,
 powerEfficient: false

}

For comparison:

MediaSource.isTypeSupported('video/mp4; codecs="av01.0.08M.08"')

Result: true

navigator.mediaCapabilities.decodingInfo({

 type: "file",
 video: {
   contentType: 'video/mp4; codecs="av01.0.08M.08"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: true,
 smooth: true,
 powerEfficient: true

}

Additional note

Setting:

dom.media.webcodecs.h265.enabled = true

causes HTML5 codec test (https://html5test.co/) to report H.265 support, but does not change:

- about:support - MediaSource.isTypeSupported() - MediaCapabilities.decodingInfo() - Twitch HEVC playback availability

Question

Is this a known issue with HEVC Media Source Extensions support on Windows 11 build 26200, or is there another requirement for Firefox to expose HEVC playback capability through MediaSource and MediaCapabilities when the Windows HEVC codec is installed and functioning in Chromium-based browsers?

Media resource could not be decoded, error: Error Code: NS_ERROR_DOM_MEDIA_DECODE_ERR (0x806e0004) Details: virtual mozilla::MediaResult mozilla::FFmpegVideoDecoder<62>::DoDecode(mozilla::MediaRawData*, uint8_t*, int, bool*, mozilla::MediaDataDecoder::DecodedData&): avcodec_send_packet error: Unknown error occurred

When I try to watch youtube, firefox will repeatedly rotate from portait to landscape. This is not what I want and there are no settings I can find to stop this. I cannot find a solution anywhere. I would like to view content the way I want, not landscape just because it is youtube.

I'm running the latest version of Firefox on the latest version of Windows 11, and I'm trying to watch TV shows on PBS's Passport service. I get the video but not the sound. It's been like this since Saturday. I don't have this problem at all with Chrome or Edge. Is anyone else having this problem? JT

Firefox is my favorite Browser because I have been able to customize it tremendously so that things do not buzz and blink and pop up at me, nothing flashes, nothing makes noise unless I deliberately permit it. today I caught Firefox for mobile permitting a video to auto play. I opened a webpage to read an article and suddenly realized that my podcast (from a different app) had been interrupted and now sound was coming from this page (clear from the content of the sound). I literally had not even seen the video in question as part of the page because I had not scrolled down far enough to where it was playing already. And when I had the lock screen on, clicking pause did not stop the video. So Video was playing without my permission, and was ignoring the usual rules of iOS.

I certainly had not clicked on the video or seen any setting that allowed the website to autoplay videos.

And this is not the first time it has happened, but it is the first time that I am positive that I did not do anything to permit this behavior, and that it had to have been the browser automatically playing something on the page. I verified that the same website does not auto play video in Safari. This is a bug in Firefox Browser for iOS .... unless there is some new setting in an updated version of the browser that says 'please bombard me with autoplay at times" which by default was switched on in a recent update.

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My issue is that when watching F1 from the following site: https://f1tv.formula1.com/, after some time (it differs in how long it takes to manifest), the stream starts to stutter. Note, it is NOT buffering, it is like the stream gets "stuck" or freezes for an instant then continues. The "freeze" then becomes more frequent and sometimes even lasts for about 2 seconds before resuming. The most important fact about all this is that this does NOT happen when using Google Chrome, hence my suspicion that it is somehow related to Firefox specifically. Does anyone have any idea what is causing this and/or how to fix it, please?

For years I have been able to watch a foreign TV website, despite having only a DSL connection (I allow only the scripts essential to make it work). Since I did the last update, to 137.0, I cannot watch either the live stream ("General source error") or old programs ("There is something wrong with your internet connection"). This is absolutely consistent; I've lost count of the times I've tried.

I never had problems like this before. At worst, if Windows was running a background process I might have to stop it to keep from having pauses in the program. All I can think of is that you did something in the new version of Firefox that has made video impossible on DSL.

I am running Firefox 144.0 on kubuntu 24.04.3 LTS I have lost sound on Firefox. I have opened the same sites in Chrome and the sound is working fine. It's only in Firefox. I have tried several sites including Udemy, YouTube, and radio programs, no sound from Firefox. The problem started in the middle of a Jit.Si session. All of a sudden the sound disappeared. I thought that restart Firefox would help, then restart the computer would help. But the problem has continued. The speakers is turned on the volume is up, just not a sound from Firefox. What to do?

Please consider looking into this as it's really annoying, it had me consider using another browser just for this issue, I ended up considering opera for example which has a much better YouTube experience on mobile, which leads me to think this is a browser issue not YouTube issue. We love Firefox, please consider fixing this. Thank you.

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about:config page link about:support page

These files are taken in integrated graphics mode.

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It would be nice if you add support MKV video with MP3 audio playback.

Video file link: https://v01d.have.lv/vp/movies/test/fm/al.mkv

Facebook videos in Firefox stop playing when clicking the Windows 11 Start button or opening Solitaire (after recent update)

This issue has just started after a Windows 11 update and restart. It has never happened before. I usually watch Facebook Reels while playing Solitaire at the same time — yes, I know, I don’t have a life.

This morning, after the update and restart, I opened Facebook and started watching a Reel as normal. As soon as I clicked the Windows Start button to open the list of programs, the video stopped. I then selected Solitaire, which opened to the taskbar. I restarted the video, clicked Solitaire to open the game fully, and the video stopped again. As soon as I minimize Solitaire, the video resumes playing.

I’ve tried all the suggestions I could find via Google, but nothing has worked so far. Note that this only affects videos playing directly on Facebook — videos playing in the Windows Media Player Legacy video player itself are not affected.

Any help would be greatly appreciated… and yes, as mentioned, I clearly don’t have a life 😅 Link to video showing what happens when I select Solitaire in the Taskbar. https://drive.google.com/file/d/1oKLIl3I4f9lfTZvbU-9pJ1gMbOU7h0zm/view?usp=sharing

Regards everyone.

More info... I run two monitors and it seem if I click on whatever I have open in the second monitor the FB video stops. So something has changed after I turned my computer on this morning and updated Windows. I even did a System Restore to a setting two days before this new update and nothing changed still have the problem.