Hello,

Few days ago I upgraded old ffmpeg-3.4.6 to ffmpeg-4.4. After Firefox restart almost all videos stopped to play. Youtube is OK. Sample videos here https://www.learningcontainer.com/mp...iles-download/ are not playable (error: No video with supported format and MIME type found). The same for some videos I recorded myself and uploaded to my cloud. I found out Firefox somehow uses ffmpeg to play videos, but ffmpeg alone plays those videos OK.

Old ffmpeg (static build I believe) was downloaded from Alien Bob's repository few years ago, when I found out I need it to play videos. Current ffmpeg-4.4 & all dependencies installed with packages from slackbuilds.org. All libraries compiled in.

Does anyone have some advice where to look? How to debug video in Firefox? How does it use the ffmpeg to play video? Is there some problem with ffmpeg ver. 4 (since ver. 3 worked)? Or is there some correct way to compile ffmpeg?

FYI I don't use Firefox from Slackware but newest downloaded from Mozilla, currently 91.0.2.

Thank you.

ico

Do you have gst-plugins-libav package installed. If not, try that first.
And I would also suggest to upgrade to Slackware64-current if you are running 14.2. Once you start updating stuff one program at a time, which involves updating all the other programs that it needs to function properly, you will end up with problems sooner or later.

Back your machine up, or at least you personal files and the /etc folder, and follow the instructions in UPGRADE.TXT. And get a copy of Slackware Live and put it on a usb. That way if you happen to mess something up and can't boot into your system, you'll have a fully functional version of Slackware you can use to go in fix things.
Hope this helps. Good Luck