I'm unable to play many HTML5 videos sourced from many common sites like ArkVid and Vimeo in Firefox. ArkVid, for example, will load one frame of the video but offers no playback controls to play the video. Vimeo appears to start loading, then abruptly stops with cutesy error messages, e.g., "Awww, snap! This video cannot be played with your current setup."

My Slackware x64 -current (as of 6 November 2015) install uses Firefox 42.0 with only the Adblock Plus add-on installed. (The Cisco H.264 add-on has been disabled.) Using older versions of Firefox (back to 38.x) do not help with this problem, nor does restarting Firefox with all add-ons disabled (in "Protected Mode").

But what puzzles me is that the same version of Firefox configured identically on Windows 7 (including ABP, sans Flash, H.264 add-on disabled) loads and plays the "problem" videos just fine. In fact, so does a stock install of the Tor Browser Bundle 5.0.x running on the same Slackware machine, as well as the version of Tor Browser bundled with Tails 1.7.

As this is almost certainly a Firefox configuration issue rather than a problem with Slackware proper, I apologize for posting to this forum. However, I am not seeing this problem in Windows 7, Tails, or a live boot of Trisquel (for testing), and my hope is that another Slackware user can at least confirm the problem. Or better still, offer pointers to how I might go about troubleshooting the matter.

Thank you!

I think you need to install gst1-libav from SBo. When I remove that package, I can't play HTML5 videos (on vimeo, for example) either. Do you have it installed?

2 members found this post helpful.

No, I did not have this library installed. And it is apparently just what I needed to get HMTL5 videos working in the browser. Thank you kindly!

Now I can get back to my DataCamp tutorials . . .

Vimeo still doesn't play HTML5 videos in Firefox 43.0.2 under -current even with the gst1-libav 1.6.2 plug-in installed.

Edit: HTML5 video playback works on YouTube with the YouTube All HTML5 extension and the gst1-libav plug-in.

I solved it by modifying the media.* settings in Firefox about:config. I also have Alien Bob's restricted ffmpeg package installed.

if you are using a asoundrc html5 will not play. It will not have sound. this goes back to 2011 when html5 video started. That means no jackd or jackd2 unless you runn a full pulseaudio and set it up through cubec.
if you must run a asoundrc then you will need to do something like this.
in /etc/modprobe.d/ create sound.conf one or if you have one.
I use everything through my headphones. so I make my usb head phones device 0.
this way below I do not need a asoundrc everything goes through my head phones. even skype with apulse.
the other way is to
again we are making it card0 /etc/modprobe.d/sound.conf
create your asoundrc
HTML5 is a joke. It is up to the web developers to embed it correctly.
And now anytime you want to use jackd it will break the sound.
I have tried rerouting alsa_in alsa_out but html5 will paly video but the sound
device will not sync and will say it is busy.

I have exactly problem with vimeo and others, but youtube html5 works flawlessly.

1 members found this post helpful.

This is because youtube supports vp8/vp9 that is shipped with slackware package, but vimeo apparently only provides mp4 and swf which is not shipped.
You could try gst1-ffmpeg, or install full ffmpeg and rebuild browser with --enable-ffmpeg --enable-fmp4 but note that I did this once before, and it's using sw rendering.
That means no vdpau, mass tearing, no vsync, and heavy load on cpu core, my previous attempts to force hw rendering into the browser were mostly inefficient or failed completely.
A dirty workaround would be extracting url from javascript src on site, and passing the stream directly to mplayer.

Just a small update: the tearing I had previously seems fixed in more recent versions of ffmpeg.
This morning I cleaned up the environment and rebuilt the thing, this is what I used:

ffmpeg-2.8.4 full with nonfree enabled
gst-ffmpeg-0.10.13 from SBo with default config
icecat-38.5.0-gnu1 built with gstreamer (not gstreamer1) and new ffmpeg

Then I tested vimeo HD it works, still uses way more cpu than mplayer, but doesn't tear at all.
I did also rebuild mplayer 1.2 stable and replaced bundled ffmpeg with new ffmpeg-2.8.4 - works fine.

The problem with firefox in -current seems that is built with gstreamer1 but gst1-ffmpeg is not on SBo
Maybe gst1-libav helps there but I didn't test on -current since it's a moving target, I only build these things on stable.

Be aware that, as of version 43, Firefox only uses Gstreamer (and thus packages like gst-ffmpeg, gst1-libav, etc) to play MP3 audio - if ffmpeg is installed at run-time, it is now used directly to play everything else. An upcoming version of Firefox will feature its own MP3 decoder (it's currently in 43 but is considered experimental, and is disabled by default); Firefox 44 will disable Gstreamer, and Firefox 46 will remove the remaining Gstreamer code from the codebase entirely.

3 members found this post helpful.

I've built gst1-libav 1.6.2 under -current using the SlackBuild-script from SBo and it seems to work. gst-ffmpeg 1.x is gst1-libav:
http://gstreamer.freedesktop.org/src...1.x-README.txt

Right. A bit confusing that plugin name, I originally thought libav was a separate ffmpeg fork and that the plugins may not be compatible.
And thanks for bugzilla links CTM, very informative, I guess if mozilla supports ffmpeg directly, they probably won't force all the media into EME adobe module then.
I'm not too keen on providing a sandbox for adobe to run encrypted modules, I'd much rather use ffh264vdpau directly.

To sum up the thread.
The fix is that you don't need gst to use firefox anymore (i removed all third-party gst-plugins) and you should use ffmpeg instead.
I installed ffmpeg from alienbob (it doesn't matter if you use restricted or not) and everything works.
http://taper.alienbase.nl/mirrors/pe...builds/ffmpeg/

1 members found this post helpful.

You almost don't need it: if you want to play MP3s directly in Firefox (i.e., streaming them without the use of an intermediate Flash applet), you'll still need Gstreamer and libmad installed and Firefox compiled with Gstreamer support (--with-gstreamer). The experimental MP3 decoder built in to Firefox apparently now works acceptably and is expected to be enabled by default as of Firefox 44, at which point Gstreamer won't be needed at all.

I didn't notice that but since i got mplayerplug-in-3.55 from extra installed it handles mp3 (looks like it in about:plugins).
Do you know what config string that enables the experimental mp3 decoder?

Creating a new Boolean named "media.mp3.enabled" and setting its value to "true" should do it. You can test the effect of doing that on this HTML5 audio codec test page.