I-Firefox Community Forum

I've been searching for an answer to this for weeks to no avail. It concerns YouTube videos "autoplay"ing on YouTube. Many have asked this question and most responses state to shut off Autoplay. These are two separate issues. AotuPlay means the next video on YouTube will advnace automatically requiring no user input. If Autoplay is off, streaming stops at the end of the video. The issue I am having is when I open a YouTube video to a new tab (but do not switch to that tab), the video WILL start playing as soon as that tab is in focus. This never used to happen and indeed, on two other computers with the settings and extensions all sync'ed, this doesn't happen, except for on this one computer. Today I found someone that posted the exact same problem 5 years ago and didn't get an answer. He seems to describe it well:

1. Okay, so before, when I loaded up 100+ Youtube videos, they stayed when switching tabs - no autoplay. Suddenly they decide to autoplay when switching tabs - note, I've not done anything to my settings or plugins. Fair enough, maybe you changed something (which you often do, without informing). So I check the options. It was on "Block audio", which obviously didn't work, so I tried "Block Audio and Video" - which WORKS, but now both the video is paused (which I want) AND the audio is set to mute (which I DON'T want) - so... what does it take to have Youtube wait for a click to start playing a video loaded in a background tab, but KEEP AUDIO ACTIVE, so I don't also have to unmute the damn video?

One person posted a possible solution: Maybe check this pref on the about:config page.

   media.block-autoplay-until-in-foreground 

This setting describes the issue kind of. If you have this set to false, the moment you send a link to a new tab, YouTube starts playing in the background. Setting it to false keeps the video paused until that tab is in focus. That is how mine has always been set. What I am looking for is a setting that would say something like: "block autoplay until play is pressed"

Thanks in advance and sorry for being so long-winded

Whenever I play something in the browser while connected to my TV by HDMI, the sound still comes out of the laptop speakers. This happened suddenly, without any discernible reason, and I can't seem to fix it. Everything else works, only content played from Firefox remains in the laptop speakers. I've checked my audio mixer, nothing seems amiss, I've updated Firefox and refreshed the application, still nothing. Hell, I've even tried different cables and HDMI ports, but nothing works. What could be the issue? Why did my audio suddenly stop working, and what can I do about it?

I've recently done a clean reinstall of Windows 11 and have noticed that, only for Firefox (134.0.2, build ID 20250120135430), a few videos playback without any audio, yet the same videos play with audio when using edge as a comparison. Most (if not all) of these videos did play with audio in Firefox prior to this reinstall.

Firstly, I'm pretty sure this is not a windows sound mixer issue since many videos on the same page and tab play back with audio just fine in Firefox. The same goes for it not relating to the Firefox setting 'Speaker selection', under (burger) > settings > privacy & security > Permissions because videos of different formats (or using different players) on the same page play back audio fine. The tab is not muted. Again, some videos on the same browser tab play audio fine; some of a particular format or player only play the video, while missing the audio (and where Edge plays the same video with audio).

Another common and potentially relevant issue I've seen is that, this being a 'Windows 11 N" install, it was initially missing the settings > system > optional features > Media feature pack, but that is now something I've successfully added. I should add that windows did report problems when I initially tried to add the media feature pack but, after a very long delay, it eventually appeared to succeed when I ran a couple of DISM incantations that I think ended with - "dism /online /add-capability /capabilityname:Media.MediaFeaturePack~~~~0.0.1.0"

I have the 'Play DRM-controlled content' setting enabled.

Comparing the Firefox vs Edge video playback on this video test page - https://tools.woolyss.com/html5-audio-video-tester/ I get the following results (don't know how to get it formatted/aligned correctly, sorry) -

                           FF vid    FF audio    Edge vid    Edge audio
av1-opus-sita.webm          Works     Works       Works       Works
vp9-vorbis-spring.webm      Works     Works       Works       Works
vp8-vorbis-sintel.webm      Works     Works       Works       Works
avc-aac-nerdist-friends.mp4 Works     MISSING     Works       Works
avc-aac-big-buck-bunny.m4v  Works     MISSING     Works       Works
avc-mp3-sita.mov            Works     Works       Works       Works

And perhaps also relevant is that there's also a difference in the audio-only samples further down the table on the same page -

                   FF audio   Edge audio
audio-sample.mp3    Works      Works
audio-sample.weba   Works      Works
audio-sample.ogg    Works      Works
audio-sample.opus   Works      Works
audio-sample.flac   Works      Works
audio-sample.wav    Works      Works
audio-sample.m4a    FAILS      Works
ac192.mp3           Works      Works
spoonradio-hd.aac   FAILS      Works
audio.opus          Works      Works

Also, every 'v.redd.it' / reddit-video-player video plays the video fine but has no sound when using Firefox but plays both sound and video fine with Edge. Here's one for example - https://old.reddit.com/r/funny/comments/1i7y1nr/rock_paper_scissors/

I've seen lots of similar (but not identical) issues on Firefox video with no audio problems with suggestions a few things to try. In addition to what I've already mentioned above, I've tried the following without success -

- Restarting Windows - Restarting Firefox - Restarting Firefox with addons/extensions disabled - 'about:support' > Refresh Firefox - 'about:support' > Clear startup cache - (hamburger) > more tools > task manager > (click the little profile icon for the page playing the video) - I've checked the settings suggested here: https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues#w_check-some-firefox-settings

I realise it may be possible to side-step this problem by flailing around with more drastic work-arounds like trying a clean re-install of Windows or a full uninstall and clean of Firefox, but that doesn't really help figure out the problem, which leaves the possibility it could easily happen again to me or others when it might be something that can be more properly fixed or guarded against in Firefox itself, so I hope someone can suggest what might be done to home in on identifying the cause of the problem and so learn whether a more precise fix can be employed.

Hi, when I launch a custom video player on a certain site and go into full screen mode, and then want to exit it through ESC, I can’t do it and the picture freezes. I went to the browser console, and it gave me this error: Uncaught (in promise) TypeError: Not in fullscreen mode

   cancelFullScreen https://interneturok.ru/assets/custom-2dc6965f3c367b4e4590249bd2036dfc.js:578
   hotkeys https://interneturok.ru/assets/custom-2dc6965f3c367b4e4590249bd2036dfc.js:675
   dispatcher https://interneturok.ru/assets/custom-2dc6965f3c367b4e4590249bd2036dfc.js:131|

The technical support of that site told me to write to the browser support, I understood the problem is not on their side. I tried everything and went through incognito mode, the problem did not go away. Give me some advice or maybe the problem is with this site and not with the browser, I also tried to launch this video player through Google Chrome and there were no problems there

This is what the GPTchat wrote about the error from the console: Yes, this error is directly related to exiting fullscreen mode. It says that the custom-2dc6965f3c367b4e4590249bd2036dfc.js script on the site is trying to exit fullscreen when the browser thinks it is no longer in it.

That is, Firefox has already exited fullscreen mode, but the player itself "thinks" that it is still there. Therefore, when you press Esc, the script calls cancelFullScreen(), and the browser throws the error "Not in fullscreen mode".

Plus screen Error

Hello,

I am having an issue with my Bluetooth headphones (Sennheiser HD 450BT) in Firefox on Windows 11.

The headphones are properly connected to Windows and work correctly with other browsers (Edge, Chrome).

Windows shows the headphones as the default output device (stereo), and test sounds play through them.

However, in Firefox, the audio does not go through the headphones. Instead, it plays very loudly through the laptop speakers.

The problem started today; there were no issues for about a year.

I have tried reconnecting/reinstalling the headphones, but it did not help. Drivers are also up to date.

Could you please advise how to make Firefox correctly use my Bluetooth headphones as the audio output device?

Thank you for your assistance.

This started almost a month ago at this point. I had been using Picture in Picture for a while and then I went to watch a new video and noticed the size was messed up.

Default view, the first picture is much larger and if there's anything on the side of the video like playlists, chat or recommended vids, the video will play under it

Theater mode has the video be pretty much the right size

Full screen is pretty much the default view but the rest is black

Sometimes if I wait a while and go back to the tab it'll be fixed but refreshing or changing the size starts it up again.

Did I break something? How do I fix this?

This is a functional bug, not a settings issue. Block media autoplay in Firefox cannot work, after I right-click on a blank area of the page and scroll.

For example, I saw a post with a video on x.com, and the site was set to prohibit automatic video playback. But when I right-clicked on the webpage and then scrolled the page with the mouse, the video started to play automatically, which means that the function of prohibiting video playback was invalid. Very strange.

Firefox version: 141.0.3 (private-browsing No extensions are running) OS: Windows11 Enterprise 26100.4946

!. link to youtube only flashes then plays only audio. Full video requires opening link in a new private browser window

2. Typing into search bar for Duck Duck Go in new tab page types directly into active bar...

3. Active bar is no longer at the top but is in Bookmarks toolbar...

I suspect some update problem.

Initially connects video playing to Headphones via Bluetooth then audio stops. Reloading doesn't help. But the same works perfectly on other browsers. Problem is with Firefox audio setting. The problem started only a week ago for firefox

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

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

So Im currently trying to watch young sheldon on netflix, and im doing it through firefox, and it wont work, it says error code f7701-1003, thank you for your time.

I have Win 11 dell computer that does not play or pick up sound from web sites videos .I checked and tested my sound using the Microsoft platform & buy playing a disc. It works OK

This issue just appeared. Video will not play in Firefox. Windows10 PC, up to date with latest versions, as is Firefox. There is no error message or code. Just the spinning wheel. I see other people are having the same issue but I haven't seen a solution. Any ideas or help appreciated.