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.

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

'h.264' and 'MSE&h.264' are disabled (on the youtube html5 test site)

  • 2 cavab
  • 10 have this problem
  • 2 views
  • Last reply by 8b533

more options

Sometimes I run into trouble with playing videos. E.g. Youtube videos suddenly are played in the flash player or clips.twitch.tv is not working at all. When I try playing the same youtube video later again, the html5 player is used again. I noticed that on the test site from youtube all codecs are working except 'h.264' and 'MSE&h.264'. I have a Windows NT installation, but the Windows media feature pack is installed correctly. If I try the same test site from youtube on chrome alls Codecs are working. I tried refreshing Firefox, completly reinstalling firefox and disabling all addons, but the problem persists. My graphics driver is on the newest version. Also the last few new versions of Firefox didn't change anything. I cant remember with which version the problems started though. Does anyone have a possible solution for this problem?

Sometimes I run into trouble with playing videos. E.g. Youtube videos suddenly are played in the flash player or clips.twitch.tv is not working at all. When I try playing the same youtube video later again, the html5 player is used again. I noticed that on the test site from youtube all codecs are working except 'h.264' and 'MSE&h.264'. I have a Windows NT installation, but the Windows media feature pack is installed correctly. If I try the same test site from youtube on chrome alls Codecs are working. I tried refreshing Firefox, completly reinstalling firefox and disabling all addons, but the problem persists. My graphics driver is on the newest version. Also the last few new versions of Firefox didn't change anything. I cant remember with which version the problems started though. Does anyone have a possible solution for this problem?

Chosen solution

hi 8b533, chrome isn't a good comparison here since they ship with their own h264 codecs instead of relying on your system's capabilities. i think the most probable cause is the windows anniversary update, since unfortunately after updating to it you'll have to download and install the media feature pack anew: Fix video and audio problems on Firefox for Windows N editions

Read this answer in context 👍 5

All Replies (2)

more options

Seçilmiş Həll

hi 8b533, chrome isn't a good comparison here since they ship with their own h264 codecs instead of relying on your system's capabilities. i think the most probable cause is the windows anniversary update, since unfortunately after updating to it you'll have to download and install the media feature pack anew: Fix video and audio problems on Firefox for Windows N editions

more options

It indeed looks like it fixed the problem. The clips from twitch are working now and on the test site from youtube all codecs are working. I could't really test the problem with the youtube videos, but I am pretty sure that it is also fixed. I was not aware that after the anniversary update there is a new media feature pack. Thank you for your quick help.