H.264 videos broken (Linux)

[dc_coder_84]

Greetings,

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/ld.so.conf.d/firefox.conf and adding the line /usr/lib/x86_64-linux-gnu. This is the directory where the shared library libavcodec.so.57 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.

[therube]

Have more then one libavcodec.so about?
Maybe it was finding, attempting to use an older version?