Firefox 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?

Since yesterday Firefox stopped working with Crunchyroll and Hidive and says, "Firefox is installing components needed to play the audio and video on this page. Please try again later."

150.0.1 (64-bit) Bazzite Linux 6.19.14-ogc1.1.fc44.x86_64 bazzite-gnome-nvidia-open:stable v44.20260501.1 Widevine plugin is version 4.10.2934.0.

Additionally, I've disabled extensions as well, cleared the cache. I've disabled play DRM content and restarted the browser before turning it back on. I've changed from my own dns server which I see nothing being blocked to google public dns and saw no difference. Everything was working fine on Wednesday night and stopped on Thursday.

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When I play YouTube videos in Firefox, the video stutters and drops frames, even when set to 480p. The audio continues to play normally. This issue does not happen in Chrome on the same laptop.

The problem started about a week ago. I’m using Firefox on Windows 11. Restarting Firefox did not resolve the issue. I’ve attached screenshots for reference.

"I’ve been having trouble with choppy YouTube videos in Firefox. It happens on both Wi-Fi and Ethernet connections. My system is running Windows 10, and I’ve already tried disabling hardware acceleration and clearing my browser cache. The issue persists even when I’m in Safe Mode. I’m using the latest version of Firefox (XX.XX). Any suggestions on how to fix this?"

Hello, I'm having a problem on Windows 10. It's a fresh windows installation and I tried already some solutions: reinstalling firefox, deleting cache, refreshing firefox, private windows, no add ons, trouble shoot mod. Nothing helped. The problem seems to be with live stream, either on twitch.tv or youtube.

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I've freshly reinstalled Windows 11 and after trying to access and watch a movie on any of these sites I get an error (see the pictures).

Browser version: 137.0.1 (64 bit) Widevine version: 4.10.2891.0

Already tried to disable/enable DRM. Already reinstalled firefox. Already manually installed widevine. No clue what could be causing this issue.

This is the link to the video that will not play in FireFox. https://www.swingtechnologies.com/UploadVideos/clarkj@pobox.com/S200629_019 B.mp4

no matter what I try I cannot get any content from HBO max, crunchyroll, or spotify to play. I feel as though I have tried every troublshooting step. In firefox 140.0.4 64 bit on windows 10 I have:

-turned DRM off and on -disabled and re-enabled widevine -disabling all extensions -try in a private tab -turning off tracking protection -clearing cookies/cache/site data -uninstalling and reinstalling firefox -trying on firefox nightly -trying on other firefox based browsers zen, librefox same issue. chromium based browsers and firefox on my windows 11 laptop play drm content like normal -manually installing older version of widevine -changing useragent to chrome(this triggered cloudflare and would not let me pass) -making another user in windows and trying there

the error i get on crunchyroll is code: DRM-0 and on spotify it loads but the play icon does nothing. in hbo max i get error code 1k-0003

At this point I don't know what else to try, If there is not another solution I probably try to just switch to brave browser or wiping this pc and reinstalling windows.