Tag Archives: open media software

Video Conferencing in HTML5: WebRTC via Web Sockets

A bit over a week ago I gave a presentation at Web Directions Code 2012 in Melbourne. Maxine and John asked me to speak about something related to HTML5 video, so I went for the new shiny: WebRTC – real-time communication in the browser.

Presentation slides

I only had 20 min, so I had to make it tight. I wanted to show off video conferencing without special plugins in Google Chrome in just a few lines of code, as is the promise of WebRTC. To a large extent, I achieved this. But I made some interesting discoveries along the way. Demos are in the slide deck.

UPDATE: Opera 12 has been released with WebRTC support.

Housekeeping: if you want to replicate what I have done, you need to install a Google Chrome Web Browser 19+. Then make sure you go to chrome://flags and activate the MediaStream and PeerConnection experiment(s). Restart your browser and now you can experiment with this feature. Big warning up-front: it’s not production-ready, since there are still changes happening to the spec and there is no compatible implementation by another browser yet.

Here is a brief summary of the steps involved to set up video conferencing in your browser:

  1. Set up a video element each for the local and the remote video stream.
  2. Grab the local camera and stream it to the first video element.
  3. (*) Establish a connection to another person running the same Web page.
  4. Send the local camera stream on that peer connection.
  5. Accept the remote camera stream into the second video element.

Now, the most difficult part of all of this – believe it or not – is the signalling part that is required to build the peer connection (marked with (*)). Initially I wanted to run completely without a server and just enter the remote’s IP address to establish the connection. This is, however, not a functionality that the PeerConnection object provides [might this be something to add to the spec?].

So, you need a server known to both parties that can provide for the handshake to set up the connection. All the examples that I have seen, such as https://apprtc.appspot.com/, use a channel management server on Google’s appengine. I wanted it all working with HTML5 technology, so I decided to use a Web Socket server instead.

I implemented my Web Socket server using node.js (code of websocket server). The video conferencing demo is in the slide deck in an iframe – you can also use the stand-alone html page. Works like a treat.

While it is still using Google’s STUN server to get through NAT, the messaging for setting up the connection is running completely through the Web Socket server. The messages that get exchanged are plain SDP message packets with a session ID. There are OFFER, ANSWER, and OK packets exchanged for each streaming direction. You can see some of it in the below image:

WebRTC demo

I’m not running a public WebSocket server, so you won’t be able to see this part of the presentation working. But the local loopback video should work.

At the conference, it all went without a hitch (while the wireless played along). I believe you have to host the WebSocket server on the same machine as the Web page, otherwise it won’t work for security reasons.

A whole new world of opportunities lies out there when we get the ability to set up video conferencing on every Web page – scary and exciting at the same time!

The new FOMS: Open Media Developers at OVC

Since 2007 I have organised the annual Foundations of Open Media Software (FOMS) developers workshop. Last year it was held for the first time in the northern hemisphere, in fact on the two days straight after the Open Video Conference (OVC).

This year I’m really excited to announce that the workshop will be an integral part of the Open Video Conference on 10-12 September 2011.

FOMS 2011 will take place as the Open Media Developers track at OVC and I would like to see as many if not more open media software developers attend as we had in last year’s FOMS.

Why should you go?

Well, firstly of course the people. As in previous years, we will have some of the key developers in open media software attend – not as celebrities, but to work with other key developers on hard problems and to make progress.

Then, secondly we believe we have some awesome sessions in preparation:

How we run it

I’m actually not quite satisfied with just these sessions. I’d like to be more flexible on how we make the three days a success for everyone. And this implies that there will continue to be room to add more sessions, even while at the conference, and create breakout groups to address really hard issues all the way through the conference.

I insist on this flexibility because I have seen in past years that the most productive outcomes are created by two or three people breaking away from the group, going into a corner and hacking up some demos or solutions to hard problems and taking that momentum away after the workshop.

To allow this to happen, we will have a plenary on the first day during which we will identify who is actually present at the workshop, what they are working on, what sessions they are planning on a attending, and what other topics they are keen to learn about during the conference that may not yet be addressed by existing sessions.

We’ll repeat this exercise on the Monday after all the rest of the conference is finished and we get a quieter day to just focus on being productive.

But is it worth the effort?

As in the past years, whether the workshop is a success for you depends on you and you alone. You have the power to direct what sessions and breakout groups are being created, and you have the possibility to find others at the workshop that share an interest and drag them away for some productive brainstorming or coding.

I’m going to make sure we have an adequate number of rooms available to actually achieve such an environment. I am very happy to have the support of OVC for this and I am assured we have the best location with plenty of space.

Trip sponsorships

As in previous FOMSes, we have again made sure that travel and conference sponsorship is available to community software developers that would otherwise not be able to attend FOMS. We have several such sponsorships and I encourage you to email the FOMS committee or OVC about it. Mention what you’re working on and what you’re interested to take away from OVC and we can give you free entry, hotel and flight sponsorship.

Oh, and don’t forget to Register for OVC!

VP8/WebM: Adobe is the key to open video on the Web

Google have today announced the open sourcing of VP8 and the creation of a new media format WebM.

Technical Challenges

As I predicted earlier, Google had to match VP8 with an audio codec and a container format – their choice was a subpart of the Matroska format and the Vorbis codec. To complete the technical toolset, Google have:

  • developed ffmpeg patches, so an open source encoding tool for WebM will be available
  • developed GStreamer and DirectShow plugins, so players that build on these frameworks will be able to decode WebM,
  • and developed an SDK such that commercial partners can implement support for WebM in their products.

This has already been successful and several commercial software products are already providing support for WebM.

Google haven’t forgotten the mobile space either – a bunch of Hardware providers are listed as supporters on the WebM site and it can be expected that developments have started.

The speed of development of software and hardware around WebM is amazing. Google have done an amazing job at making sure the technology matures quickly – both through their own developments and by getting a substantial number of partners included. That’s just the advantage of being Google rather than a Xiph, but still an amazing achievement.


As was to be expected, Google managed to get all the browser vendors that are keen to support open video to also support WebM: Chrome, Firefox and Opera all have come out with special builds today that support WebM. Nice work!

What is more interesting, though, is that Microsoft actually announced that they will support WebM in future builds of IE9 – not out of the box, but on systems where the codec is already installed. Technically, that is be the same situation as it will be for Theora, but the difference in tone is amazing: in this blog post, any codec apart from H.264 was condemned and rejected, but the blog post about WebM is rather positive. It signals that Microsoft recognize the patent risk, but don’t want to be perceived of standing in the way of WebM’s uptake.

Apple have not yet made an announcement, but since it is not on the list of supporters and since all their devices exclusively support H.264 it stands to expect that they will not be keen to pick up WebM.


What is also amazing is that Google have already achieved support for WebM by several content providers. The first of these is, naturally, YouTube, which is offering a subset of its collection also in the WebM format and they are continuing to transcode their whole collection. Google also has Brightcov, Ooyala, and Kaltura on their list of supporters, so content will emerge rapidly.


So, where do we stand with respect to a open video format on the Web that could even become the baseline codec format for HTML5? It’s all about uptake – if a substantial enough ecosystem supports WebM, it has all chances of becoming a baseline codec format – and that would be a good thing for the Web.

And this is exactly where I have the most respect for Google. The main challenge in getting uptake is in getting the codec into the hands of all people on the Internet. This, in particular, includes people working on Windows with IE, which is still the largest browser from a market share point of view. Since Google could not realistically expect Microsoft to implement WebM support into IE9 natively, they have found a much better partner that will be able to make it happen – and not just on Windows, but on many platforms.

Yes, I believe Adobe is the key to creating uptake for WebM – and this is admittedly something I have completely overlooked previously. Adobe has its Flash plugin installed on more than 90% of all browsers. Most of their users will upgrade to a new version very soon after it is released. And since Adobe Flash is still the de-facto standard in the market, it can roll out a new Flash plugin version that will bring WebM codec support to many many machines – in particular to Windows machines, which will in turn enable all IE9 users to use WebM.

Why would Adobe do this and thus cement its Flash plugin’s replacement for video use by HTML5 video? It does indeed sound ironic that the current market leader in online video technology will be the key to creating an open alternative. But it makes a lot of sense to Adobe if you think about it.

Adobe has itself no substantial standing in codec technology and has traditionally always had to license codecs. Adobe will be keen to move to a free codec of sufficient quality to replace H.264. Also, Adobe doesn’t earn anything from the Flash plugins themselves – their source of income are their authoring tools. All they will need to do to succeed in a HTML5 WebM video world is implement support for WebM and HTML5 video publishing in their tools. They will continue to be the best tools for authoring rich internet applications, even if these applications are now published in a different format.

Finally, in the current hostile space between Apple and Adobe related to the refusal of Apple to allow Flash onto its devices, this may be the most genius means of Adobe at getting back at them. Right now, it looks as though the only company that will be left standing on the H.264-only front and outside the open WebM community will be Apple. Maybe implementing support for Theora wouldn’t have been such a bad alternative for Apple. But now we are getting a new open video format and it will be of better quality and supported on hardware. This is exciting.

IP situation

I cannot, however, finish this blog post on a positive note alone. After reading the review of VP8 by a x.264 developer, it seems possible that VP8 is infringing on patents that are outside the patent collection that Google has built up in codecs. Maybe Google have calculated with the possibility of a patent suit and put money away for it, but Google certainly haven’t provided indemnification to everyone else out there. It is a tribute to Google’s achievement that given a perceived patent threat – which has been the main inhibitor of uptake of Theora – they have achieved such an uptake and industry support around VP8. Hopefully their patent analysis is sound and VP8 is indeed a safe choice.

UPDATE (22nd May): After having thought about patents and the situation for VP8 a bit more, I believe the threat is really minimal. You should also read these thoughts of a Gnome developer, these of a Debian developer and the emails on the Theora mailing list.

Accessibility support in Ogg and liboggplay

At the recent FOMS/LCA in Wellington, New Zealand, we talked a lot about how Ogg could support accessibility. Technically, this means support for multiple text tracks (subtitles/captions), multiple audio tracks (audio descriptions parallel to main audio track), and multiple video tracks (sign language video parallel to main video track).

Creating multitrack Ogg files
The creation of multitrack Ogg files is already possible using one of the muxing applications, e.g. oggz-merge. For example, I have my own little collection of multitrack Ogg files at http://annodex.net/~silvia/itext/elephants_dream/multitrack/. But then you are stranded with files that no player will play back.

Multitrack Ogg in Players
As Ogg is now being used in multiple Web browsers in the new HTML5 media formats, there are in particular requirements for accessibility support for the hard-of-hearing and vision-impaired. Either multitrack Ogg needs to become more of a common case, or the association of external media files that provide synchronised accessibility data (captions, audio descriptions, sign language) to the main media file needs to become a standard in HTML5.

As it turn out, both these approaches are being considered and worked on in the W3C. Accessibility data that are audio or video tracks will in the near future have to come out of the media resource itself, but captions and other text tracks will also be available from external associated elements.

The availability of internal accessibility tracks in Ogg is a new use case – something Ogg has been ready to do, but has not gone into common usage. MPEG files on the other hand have for a long time been used with internal accessibility tracks and thus frameworks and players are in place to decode such tracks and do something sensible with them. This is not so much the case for Ogg.

For example, a current VLC build installed on Windows will display captions, because Ogg Kate support is activated. A current VLC build on any other platform, however, has Ogg Kate support deactivated in the build, so captions won’t display. This will hopefully change soon, but we have to look also beyond players and into media frameworks – in particular those that are being used by the browser vendors to provide Ogg support.

Multitrack Ogg in Browsers
Hopefully gstreamer (which is what Opera uses for Ogg support) and ffmpeg (which is what Chrome uses for Ogg support) will expose all available tracks to the browser so they can expose them to the user for turning on and off. Incidentally, a multitrack media JavaScript API is in development in the W3C HTML5 Accessibility Task Force for allowing such control.

The current version of Firefox uses liboggplay for Ogg support, but liboggplay’s multitrack support has been sketchy this far. So, Viktor Gal – the liboggplay maintainer – and I sat down at FOMS/LCA to discuss this and Viktor developed some patches to make the demo player in the liboggplay package, the glut-player, support the accessibility use cases.

I applied Viktor’s patch to my local copy of liboggplay and I am very excited to show you the screencast of glut-player playing back a video file with an audio description track and an English caption track all in sync:


Further developments
There are still important questions open: for example, how will a player know that an audio description track is to be played together with the main audio track, but a dub track (e.g. a German dub for an English video) is to be played as an alternative. Such metadata for the tracks is something that Ogg is still missing, but that Ogg can be extended with fairly easily through the use of the Skeleton track. It is something the Xiph community is now working on.

This is great progress towards accessibility support in Ogg and therefore in Web browsers. And there is more to come soon.

Video Streaming from Linux.conf.au

You probably heard it already: Linux.conf.au is live streaming its video in a Microsoft proprietary format.

Fortunately, there is now a re-broadcast that you can get in an open format from http://stream.v2v.cc:8000/ . It comes from a server in Europe, but relies on transcoding here in New Zealand, so it may not be completely reliable.

UPDATE: A second server is now also available from the US at http://repeater.xiph.org:8000/.

Today, the down under open source / Linux conference linux.conf.au in Wellington started with the announcement that every talk and mini-conf will be live streamed to the Internet and later published online. That’s an awesome achievement!

However, minutes after the announcement, I was very disappointed to find out that the streams are actually provided in a proprietary format and through a proprietary streaming protocol: a Microsoft streaming service that provides Windows media streams.

Why stream an open source conference in a proprietary format with proprietary software? If we cannot use our own technologies for our own conferences, how will we get the rest of the world to use them?

I must say, I am personally embarrassed, because I was part of several audio/video teams of previous LCAs that have managed to record and stream content in open formats and with open media software. I would have helped get this going, but wasn’t aware of the situation.

I am also the main organiser of the FOMS Workshop (Foundations of Open Media Software) that ran the week before LCA and brought some of the core programmers in open media software into Wellington, most of which are also attending LCA. We have the brains here and should be able to get this going.

Fortunately, the published content will be made available in Ogg Theora/Vorbis. So, it’s only the publicly available stream that I am concerned about.

Speaking with the organisers, I can somewhat understand how this came to be. They took the “easy” way of delegating the video work to an external company. Even though this company is an expert in open source and networking, their media streaming customers are all using Flash or Windows media software, which are current de-facto standards and provide extra features such as DRM. It seems apart from linux.conf.au there were no requests on them for streaming Ogg Theora/Vorbis yet. Their existing infrastructure includes CDN distribution and CDN providers certainly typically don’t provide Ogg Theora/Vorbis support or Icecast streaming.

So, this is actually a problem founded in setting up streaming through a professional service rather than through the community. The way in which this was set up at other events was to get together a group of volunteers that provided streaming reflectors for free. In this way, a community-created CDN is built that can deal with the streams. That there are no professional CDN providers available yet that provide Icecast support is a sign that there is a gap in the market.

But phear not – a few of the FOMS folk got together to fix the situation.

It involved setting up Icecast streams for each room’s video stream. Since there is no access to the raw video stream, there is a need to transcode the video from proprietary codecs to the open Ogg Theora/Vorbis format.

To do this legally, a purchase of the codec libraries from Fluendo was necessary, which cost a whopping EURO 28 and covers all the necessary patent licenses. The glue to get the videos from mms to icecast streams is a GStreamer pipeline which I leave others to talk about.

Now, we have all the streams from the conference available as Ogg Theora/Video streams, we can also publish them in HTML5 video elements. Check out this Web page which has all the video streams together on a single page. Note that the connections may be a bit dodgy and some drop-outs may occur.

Further, let me recommend the Multimedia Miniconf at linux.conf.au, which will take place tomorrow, Tuesday 19th January. The Miniconf has decided to add a talk about “How to stream you conference with open codecs” to help educate any potential future conference organisers and point out the software that helps solve these issues.

UPDATE: I should have stated that I didn’t actually do any of the technical work: it was all done by Ralph Giles, Jan Gerber, and Jan Schmidt.

FOMS and LCA Multimedia Miniconf

If you haven’t proposed a presentation yet, got ahead and register yourself for:

FOMS (Foundations of Open Media Software workshop) at

LCA Multimedia Miniconf at

It’s already November and there’s only Christmas between now and the conferences!

I’m personally hoping for many discussions about HTML5 <video> and <audio>, including what to do with multitrack files, with cue ranges, and captions. These should also be relevant to other open media frameworks – e.g. how should we all handle multitrack sign language tracks?

But there are heaps of other topics to discuss and anyone doing any work with open media software will find a fruitful discussions at FOMS.

Professional Tool support for open media codecs

Michael Dale from Metavid has posted an article on why we are about to hit the tipping point for professional video producers to move to open media codecs. His statement is that it’s not just because the H.264 licensing grace period is about to end, but has a lot to do with the support that open media codecs are increasingly seeing on the Web, where the next big professional video market will happen. I totally agree.

The increasing amount of open tools on the Web for open codecs was all stimulated by the HTML5 <video> element and is based on year-long efforts that have gone into Annodex and applications using Annodex technology such as Metavid. There is now Firefox 3.1’s native support for Ogg Theora/Vorbis through liboggplay, there is the mod_annodex Apache plugin and the oggzchop CGI tool to serve time ranges of Ogg media over HTTP from Web Servers, there is the new firefogg Firefox Ogg Theora/Vorbis encoding plugin, and this all closes the tool-chain from encoding to publishing to viewing.

Native editing of Ogg Theora/Vorbis video is still a challenge, but any professional video producer will not want to move away from their favorite tool for editing video anyway, so it is a matter of having an export function included into these professional editors. While such export functions will take some time to emerge in these proprietary editors, the use of ffmpeg2theora and similar transcoding tools will be perfectly sufficient to fulfill these needs.

If you want to see why open source codecs and open video technology make such a difference, just go and check out Metavid, the best software around for wiki-style editing of time-aligned annotations for long-form video. I look forward to all the cool new applications that will emerge with open media software on the Web – applications that are not possible with proprietary video technology because of their lack of flexibility, interoperability, and adaptability.