Full-screen HD streaming video playback in Firefox on Linux

Apr 9, 2015 · 2 min read ·

Video playback from HTML5 sources such as youtube, vimeo and vessel has been slow and choppy in Firefox, while they all worked well in Chrome (I’m on a slow, old box, the CPU is Core2 Duo, the video card is more recent, nVidia GTX650 with the proprietary drivers). Finally, I’ve found that Firefox 37 allowed me to play back everything at good speed and full resolution (1080p) at full screen with the following settings:

Firefox -> Preferences -> Advanced -> General -> Use hardware acceleration when available: YES
about:config
media.mediasource.enabled = true
media.mediasource.mp4.enabled = false (if set to true, youtube would not play videos with the HTML5 player at all)
media.mediasource.webm.enabled = true
media.mediasource.youtubeonly = true

(01/) Updated settings for Firefox 40 (Kofa, 2015-08-18)

media.mediasource.enabled from false to true media.mediasource.webm.enabled from false to true media.mediasource.mp4.enabled from false to true media.fragmented-mp4.use-blank-decoder from true to false media.fragmented-mp4.* from false to true Right click and create a new Bolean entry with the name “media.mediasource.ignore_codecs” and set it to true

Quoted from http://news.softpedia.com/news/how-to-enable-1080p-youtube-support-in-firefox-40-for-linux-users-489491.shtml

I also removed (reset to empty default) media.mediasource.youtubeonly

(02/) Firefox 43 (Kofa, 2015-12-17)

According to https://bbs.archlinux.org/viewtopic.php?id=206285:

In previous version I manually edited some things in about:config regarding html5 video, so that was the cause of the problem. The new Firefox uses ffmpeg by default, instead of gstreamer. To fix it, I set media.fragmented-mp4.gmp.enabled to false.