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Videos / mp4s will not play in Firefox

Posted

Videos, like mp4 Vines, won't play in Firefox. Same with the media files like podcasts in rss feeds. All used to work fine. This is an intermittent problem with Firefox ( might be due to updates ) but it doesn't happen with IE or Chrome

If i uninstall VLC player or disable the VLC plugin, nothing happens If i have those installed but the VLC plugin is set to " Never activate ", i can right click on the video image, click " Play " and it opens in VLC player and works perfectly. If i have the plugin set to " always activate " then i see a black square and the message " the video can't be played because the file is corrupt "

Windows 8.1, Firefox 35.

This is an issue with Firefox and needs to be resolved.

Videos, like mp4 Vines, won't play in Firefox. Same with the media files like podcasts in rss feeds. All used to work fine. This is an intermittent problem with Firefox ( might be due to updates ) but it doesn't happen with IE or Chrome If i uninstall VLC player or disable the VLC plugin, nothing happens If i have those installed but the VLC plugin is set to " Never activate ", i can right click on the video image, click " Play " and it opens in VLC player and works perfectly. If i have the plugin set to " always activate " then i see a black square and the message " the video can't be played because the file is corrupt " Windows 8.1, Firefox 35. This is an issue with Firefox and needs to be resolved.

Chosen solution

media.windows-media-foundation.enabled

this was set to false. I switched it to true and now everything is fine again. Others who've encountered the same problem have switched it from true to false as a successful solution.


How can this be ? What does that line do - is it for the built in media player ?

Read this answer in context 1

Additional System Details

Installed Plug-ins

  • GEPlugin
  • Google Update
  • Shockwave Flash 16.0 r0

Application

  • User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0

More Information

guigs 1072 solutions 11697 answers

Hi Ipcress, In order to further investigate when might be causing the corrupt error, can you please confirm which codec the videos that are not working are in, or an example url where this is happening?

For further troubleshooting of this error: Fix common audio and video issues

Hi Ipcress, In order to further investigate when might be causing the corrupt error, can you please confirm which codec the videos that are not working are in, or an example url where this is happening? For further troubleshooting of this error: [[Fix common audio and video issues]]
cor-el
  • Top 10 Contributor
  • Moderator
17537 solutions 158573 answers

That is a problem with the HTML5 media player. It is possible that you previously used the Flash plugin and that you now get offered the video tag to use the HTML5 media player.

Do related media prefs still have the default value?

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

See also: Media Feature Pack for Windows 8.1 N and Windows 8.1 KN Editions: April 2014:

That is a problem with the HTML5 media player. It is possible that you previously used the Flash plugin and that you now get offered the video tag to use the HTML5 media player. Do related media prefs still have the default value? You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I'll be careful" to continue. *http://kb.mozillazine.org/about:config See also: Media Feature Pack for Windows 8.1 N and Windows 8.1 KN Editions: April 2014: *http://support.microsoft.com/kb/2929699

Question owner

Hi. Thanks for the replies

It's things like vines in twitter feeds which used to play once within the browser but now need to be opened by an external player. Here are examples of the preferences

media.fragmented-mp4.enabled - default - boolean - true media.fragmented-mp4.ffmpeg.enabled - default - boolean - false

Hi. Thanks for the replies It's things like vines in twitter feeds which used to play once within the browser but now need to be opened by an external player. Here are examples of the preferences media.fragmented-mp4.enabled - default - boolean - true media.fragmented-mp4.ffmpeg.enabled - default - boolean - false

Chosen Solution

media.windows-media-foundation.enabled

this was set to false. I switched it to true and now everything is fine again. Others who've encountered the same problem have switched it from true to false as a successful solution.


How can this be ? What does that line do - is it for the built in media player ?

media.windows-media-foundation.enabled this was set to false. I switched it to true and now everything is fine again. Others who've encountered the same problem have switched it from true to false as a successful solution. How can this be ? What does that line do - is it for the built in media player ?
cor-el
  • Top 10 Contributor
  • Moderator
17537 solutions 158573 answers

When these prefs are set to false then you disable the HTML5 media player for H.264 media and that includes mp4 files.

  • media.windows-media-foundation.enabled
  • media.directshow.enabled
When these prefs are set to false then you disable the HTML5 media player for H.264 media and that includes mp4 files. *media.windows-media-foundation.enabled *media.directshow.enabled *https://support.mozilla.org/kb/viewing-html5-audio-and-video

Question owner

So why have others had to set them to false for the vids to work ?

So why have others had to set them to false for the vids to work ?