Firefox cannot play mp4 files on windows 7
I'm using firefox 30 on Windows 7. I was under the impression Firefox supported mp4 playback in this configuration as described at https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats but I can't get it to work anywhere.
webm and ogg theora work fine but mp4 playback doesn't. Some sites I've tested: http://www.quirksmode.org/html5/tests/video.html - top video does not load www.quirksmode.org/html5/tests/video.html - left side videos do not load https://vine.co/ - video playback fails completley youtube with html5 player- video playback fails completely
Does anyone have any solutions?
All Replies (11)
Do you have a Windows version that comes with Windows Media Foundation and this enabled?
You can also check these prefs on the about:config page.
- media.windows-media-foundation.enabled
- media.directshow.enabled
thanks for your response
I am using Windows 7 Ultimate which has windows media foundation to my knowledge.
both media.windows-media-foundation.enabled and media.directshow.enabled are set yo true
You can open the Web Console (Firefox/Tools > Web Developer) and check for issues with loaded media files.
To rule out extensions as a possible culprit, could you try the test pages in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions, some advanced features, and some custom settings. More info: Diagnose Firefox issues using Troubleshoot Mode.
You can restart Firefox in Safe Mode using either
- "3-bar" menu button > "?" button > Restart with Add-ons Disabled
- (menu bar) Help menu > Restart with Add-ons Disabled
Note: Flash and other plugins still run
After Firefox closes, a small dialog should appear: click "Start in Safe Mode" (not Reset)
Any difference?
With the last Firefox upgrade, some plugins are no longer enabled until you enable it.
Open the Add-ons Manager. Press the <Alt> or <F10> key to bring up the tool bar. Followed by;
Tools' Add-ons.
Hot key; <Control> (Mac: <Command>) <Shift> A)
On the left side of the page, select Plugins.
BTW; At the top right is a link to check your plugins.
Modified by James
In the console I see this for each video: Media resource <file path> could not be decoded.
Starting in safe mode gives the same result. I've tried enabling/disabling all browser plugins and also disabling plugin scanning but I get the same error regardless.
Are you using any kind of blocking software in Firefox or your computer?
No blocking software, all addons/plugins disabled and still the same problem.
It is likely that you do not have the codec to play such a file via the HTML5 media player.
Does Firefox use another player if you disable the HTML5 media player?
As a test you can disable the HTML5 media player by toggling these prefs to false on the about:config page.
- media.directshow.enabled
- media.windows-media-foundation.enabled
Firefox uses flash when those settings are disabled.
Is there a way to install the codec? I thought Firefox could play mp4 on Windows 7.
Modified by homunyan
Maybe your mp4 file has some problem. You can try another mp4 file to have a test. Change your mp4 file to webm also is fine to have a try. http://www.firecoresoft.com/convert-mp4/convert-mp4-to-webm.html