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mp4 video plays but with no sound (W7, f/f 64bit, v75.0)

  • 3 replies
  • 1 has this problem
  • 4 views
  • Last reply by Gra

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A .mp4 video clip on the web will play through f/f but with no sound. A .mp3 audio clip plays ok. The laptop sound controls are not muted. The mp4 clip shows a bar at the bottom and on the right there's a symbol that looks like a speaker with a bar through it. There seems no way to change this. The mp4 clip will play perfectly in WMP and from the website on a Samsung phone.

A .mp4 video clip on the web will play through f/f but with no sound. A .mp3 audio clip plays ok. The laptop sound controls are not muted. The mp4 clip shows a bar at the bottom and on the right there's a symbol that looks like a speaker with a bar through it. There seems no way to change this. The mp4 clip will play perfectly in WMP and from the website on a Samsung phone.

Chosen solution

There was a similar thread last year but I'm not sure we really got to the bottom of it: https://support.mozilla.org/questions/1268331

It's possible that Firefox is displaying messages about the problem in its Web Console. You can open the Web Console in the lower part of the tab using either:

  • "3-bar" menu button > Web Developer > Web Console
  • (menu bar) Tools > Web Developer > Web Console
  • (Windows) Ctrl+Shift+k

You can clear existing clutter by clicking the little garbage can icon above the existing list.

Then reload the page or re-trigger the media to play in the upper part of the tab and watch for error or security messages. Anything that sounds like it could be relevant?

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All Replies (3)

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Chosen Solution

There was a similar thread last year but I'm not sure we really got to the bottom of it: https://support.mozilla.org/questions/1268331

It's possible that Firefox is displaying messages about the problem in its Web Console. You can open the Web Console in the lower part of the tab using either:

  • "3-bar" menu button > Web Developer > Web Console
  • (menu bar) Tools > Web Developer > Web Console
  • (Windows) Ctrl+Shift+k

You can clear existing clutter by clicking the little garbage can icon above the existing list.

Then reload the page or re-trigger the media to play in the upper part of the tab and watch for error or security messages. Anything that sounds like it could be relevant?

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jscher2000 - -I tried that - web console shows no errors or warnings. But looking at the link to previous problem, setting media.play-stand-alone to false forces the file to be opened outside f/f in WMP and then it plays correctly. So I have a good work-around, but there's still a problem within f/f not solved. Thanks v much for the quick response.


hansigaya99 - In my case, WMP plays it properly when started outside f/f, so not sure if this is going to help. However, the page has got some useful looking content and I'll give it a go in due course. Thanks v much!