H.264 videos broken (Linux)

User Help for Mozilla Firefox
Posts: 8
Joined: May 31st, 2015, 1:55 am

Post Posted January 28th, 2018, 1:03 pm


Since two days I couldn't play h.264 encoded videos in Firefox on my Xubuntu 17.10 64 bit system. I got this error message when ever I wanted to play such a video:

Libavcodec may be vulnerable or is not supported, and should be updated to play video.

On the Youtube HTML5 Support page "H.264" and "MSE & H.264" was unchecked.

I solved the problem by creating the file /etc/ and adding the line /usr/lib/x86_64-linux-gnu. This is the directory where the shared library resides.

I got the idea to this solution from a German thread where somebody had a very similar problem or maybe the same.

Before I solved the problem I tested various things. I downgraded from Firefox version 58 to 56. Same problem. I tried Firefox Nightly. Same problem. I tested Chromium and mpv (with mpv URL). They had no problem with playing these videos. I also checked several package installations regarding the libavcodec. Everything seemed fine there.

I am leaving these notes here in case somebody else has this problem.

Does anybody have an idea what could be the problem? Why do I suddenly need to add the path to the decoder library? I am not sure if the problem is within firefox or if it has to do with OS updates.
Last edited by DanRaisch on January 28th, 2018, 5:24 pm, edited 1 time in total.
Reason: (Linux) added to subject line.


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Joined: March 10th, 2004, 9:59 pm
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Post Posted January 29th, 2018, 11:16 am

Have more then one about?
Maybe it was finding, attempting to use an older version?
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv: Gecko/20110420 SeaMonkey/2.0.14 Pinball CopyURL+ FetchTextURL FlashGot NoScript

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