I-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?

I think everyone knows how to get out of full screen mode by now, so can you either remove it or let us disable that little box that always shows when you go full screen for a video?

Hello, I am currently using windows 11 with firefox 149.0. Regardless of what website I use (youtube. steam etc), the browser struggles to establish consistent connection to my bluetooth earbuds. It connects for one moment, but then soon the volume goes out and eventually it disconnects. Though it would reconnect soon, the cycle just keeps ongoing. I have experimented with other apps and browsers, as well as multiple bluetooth earbuds of other brands to be sure that it is a firefox issue. I have checked the volume mixer menu to ensure that there is nothing wrong. I have also made sure that my drivers are all up to date with no issue. But the issue still persists.

频繁使用视频快进/后退，会导致Windows 音频设备图形隔离（audiodg.exe）内存泄露，

复现： 浏览任意视频，使用方向键左右频繁切换快进/后退， 可以看到内存逐步增加，退出浏览无法得到完全释放， 若长时间使用最终会导致内存泄露，如播放列表频繁使用快进/后退 // 已尝试更新相关驱动，关闭部分音频相关功能，无法得到解决，目前推测是firefox问题， 使用microsoft edge尝试复现，无此问题

Hello, I am facing an issue while playing YouTube videos in Firefox. The videos are lagging and not playing smoothly, even though my internet connection is fine. Please help me fix this problem.

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.

No audio on Firefox. Google Chrome has sound. Settings at normal audio volumes. Tried computer shut off and re-boot. Tried reload of Firebox.but that didn't help. Had scam attempt just before no audio issue...not sure if that problem.

I couldn't sign my Alejandra .com on my computer so i need to cahnge to Firefox aboutpreferences@tabsBrwosing so the video from Aljazeera video live news awork on my computer Thank kind regards Peter tan

I am using FF desktop. All of a sudden, I get no sound through my laptop speakers when trying to watch videos (on YT and FB for example). I still get sound if I use external speakers through the 3.5" jack. I still get sound through other browsers, no matter if it's through the laptop speakers or external ones. So, it is definitely an FF problem. Sound works fine on all other media files on the laptop. Refreshing FF didn't fix it. Nor did reinstalling or restarting the laptop. I tried changing the autoplay settings as suggested in the help article, but still no laptop audio via FF. How can I fix this? Thanks

Good evening Mozilla,

Well I am facing an issue, no sound coming from any website like netflix or youtube or prime from mozilla browser.

Could you please fix it for me.

Regards