Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

No H.264/mp4 video playback (FF57x64 Win10Home)

  • 4 replies
  • 8 have this problem
  • 2 views
  • Last reply by kkkkzk

kkkkzk
kkkkzk
more options

I can't play videos on Facebook.

I am using Firefox 57.0.4 x64.

Firefox console says:

No decoders: video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401f", video/mp4; codecs="avc1.4d401f", audio/mp4; codecs="mp4a.40.5", video/mp4; codecs="avc1.42E01E mp4a.40.2", video/mp4; codecs="avc1.4D401E mp4a.40.2", video/mp4; codecs="avc1.4D401F mp4a.40.2", video/mp4; codecs="avc1.640032 mp4a.40.2", video/mp4; codecs="avc1.640033 mp4a.40.2"

Youtube html5 test says no H.264 and no MSE & H.264.

I'm on Windows 10 Home WITHOUT any "N"-s, so that Windows Media Feature Pack would be missing.

I have tried all solutions presented to similar problems. None of them worked.

How can I make it work?

I can't play videos on Facebook. I am using Firefox 57.0.4 x64. Firefox console says: No decoders: video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401e", video/mp4; codecs="avc1.4d401f", video/mp4; codecs="avc1.4d401f", audio/mp4; codecs="mp4a.40.5", video/mp4; codecs="avc1.42E01E mp4a.40.2", video/mp4; codecs="avc1.4D401E mp4a.40.2", video/mp4; codecs="avc1.4D401F mp4a.40.2", video/mp4; codecs="avc1.640032 mp4a.40.2", video/mp4; codecs="avc1.640033 mp4a.40.2" Youtube html5 test says no H.264 and no MSE & H.264. I'm on Windows 10 Home WITHOUT any "N"-s, so that Windows Media Feature Pack would be missing. I have tried all solutions presented to similar problems. None of them worked. How can I make it work?

Chosen solution

None of these did work either. I have wasted so much time on troubleshooting this it turned out that formatting C: was a faster solution :(.

Anyway, thanks for your help!

Read this answer in context 👍 1

All Replies (4)

James
James
  • Moderator
  • Top 10 Contributor
more options

https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows

kkkkzk
kkkkzk Question owner
more options

Thanks for the answer.

Maybe I've constructed that sentence in a weird way, but what I meant was that it is a regular Windows version, with the Windows Media Features installed, so that solution you suggested won't do anything.

James
James
  • Moderator
  • Top 10 Contributor
more options

Some people have had issues with HTML5 player on Youtube and other sites due to extensions like Youtube Flash or force HTML5 player or such installed in Firefox.

Type about:config with a : in Location (address) bar and make sure none of the below Preferences are user set, if any are then double-click them to restore the default value of true

  • media.mediasource.enabled
  • media.mediasource.mp4.enabled
  • media.mp4.enabled
  • media.ogg.enabled
  • media.webm.enabled

After this try the https://www.youtube.com/html5 page again.

Modified by James

kkkkzk
kkkkzk Question owner
more options

Chosen Solution

None of these did work either. I have wasted so much time on troubleshooting this it turned out that formatting C: was a faster solution :(.

Anyway, thanks for your help!