You can check the Web Console (Tools -> Web Developer) for messages about blocked content and about the presence of mixed or unsafe content.

• https://developer.mozilla.org/en/Tools/Web_Console

You can check the Network Monitor to see if content is blocked or otherwise fails to load.

• https://developer.mozilla.org/en/Tools/Network_Monitor

If necessary use "Ctrl+F5" or "Ctrl+Shift+R" to reload the page and bypass the cache to generate a fresh log.

I believe it is some incompatibility between Firefox and Facebook. Is there something special in the way Facebook presents videos that might be affecting the audio? And it's just the audio. The video plays with no problem. Those videos that have YouTube versions play fine in YouTube, but not on Facebook.

Only thing I have seen for and suggest for Windows in Reinstall and delete all FF folders. With Linux no answer for you.

SAFE MODE

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder)
• default toolbar layout is used (file: localstore-safe.rdf)
• Javascript JIT compilers are disabled (prefs: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)
• plugins are not affected
• preferences are not affected

TEST

drichard58 said

I believe it is some incompatibility between Firefox and Facebook. Is there something special in the way Facebook presents videos that might be affecting the audio? And it's just the audio. The video plays with no problem. Those videos that have YouTube versions play fine in YouTube, but not on Facebook.

May be silly but make sure the Facebook videos when playing are not muted with X on speaker icon.

LOL - I have done some silly things like having the speakers muted, so I double checked.

In Linux, I did clear the cache and all the stored data that I could find and disabled all the add-ons one by one. Even with all them disabled, I can still hear YouTube videos but can't here Facebook audio.

Any luck with a Private Browsing mode window in case some data is still present?

Isn't there anything in the Web Console or Browser Console that is media related?

I tried it in the private browser and still no audio. I have to admit, I am not sure what I am looking for in the consoles, but there was nothing in there that said "error".

If Linux then you want to also post to a Linux forum matching your version and asking those developers if there is something missing to cause this as well. FF doesn't install Sounds Drivers.

You can create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Out of curiosity do all of the test videos on https://www.quirksmode.org/html5/tests/video.html load audio?

I had a issue over two years ago where a package update for audio made it so audio in Flash Player (NPAPI) would not work however the audio worked fine in HTML5 and PPAPI Flash Player (using freshplayer wrapper) and audio worked in videos played in a media player like mpv and mplayer. I ended up reinstalling my openSuse 13.2 each time to fix this back then.

COR-EL: I tried creating a new profile and that one does not work either.

JAMES: Thanks for sharing the web site. As per the site, Firefox does not handle the MP4 (and the video did play, but no audio). The other two videos - WebM and Ogg - played the audio with no issue.

Is MP4 maybe a standard format for Facebook videos?