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Quality switches to 360 when tab inactive firefox. I watch Twitch in 1080p. When I switch to another tab and then return, the quality drops to 360p and then automatically goes back to 1080p.

(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?

For the past.. month I would say, any time I try to use Youtube on my Firefox Browser it nearly always switches over to landscape mode after watching a video. It doesn't matter whether my phone screen's auto rotate is on or off it still does it. Yes. I already tried to turn my auto rotate on to switch it back to potrait mode, it still won't work. The only solution I currently have is closing Youtube all together from my Browser, which really REALLY sucks!!

Can someone PLEASE look into the glitch?!

audio stops completely for exactly 0.4 seconds when un-pausing video, this affects any "interruptions" including skipping around, clicking on timestamps and any ohter type. issue stops completely when another youtube tab with a video playing is currently active.

i have tried any regular troubleshooting tips, including any and all forums i've found online to no avail. this is not happening in any other browser.

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i basically got like 2-3 completely different users muted for no reason, but at the moment i can only remember 1 of them and noone else has been added to the bug list ever since... and it basically happened when the Firefox itself got really low on memory again and started to display that red crash button. and even then, many different users crashed, but some did not even get the sound back anymore, while others did with no issue....

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For the past.. month I would say, any time I try to use Youtube on my Firefox Browser it nearly always switches over to landscape mode after watching a video. It doesn't matter whether my phone screen's auto rotate is on or off it still does it. Yes. I already tried to turn my auto rotate on to switch it back to potrait mode, it still won't work. The only solution I currently have is closing Youtube all together from my Browser, which really REALLY sucks!!

Can someone PLEASE look into the glitch?!

Hi,

The Firefox browser came through with an update and I found that on Bluesky it is hard to load or see video's, which makes it a slightly pointless exercise.

Previously I have found that after an update (can't recall if it was Chrome, but think it was Firefox) the problems cleared up after a couple of days.

However, that doesn't seem to be happening right now.

Can't think what I should be tweaking at my end.

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

Whenever I try to full screen in any streaming websites, it's not full screen at all. There is a little bit of space in the left-side and top-side of the screen where the other windows or applications I have can be seen (or my desktop if nothing else is open). This is not happening to other browsers. Can you please help me to fix this?