Category Archives: FOMS

First experiments with itext

My accessibility work for Mozilla is showing first results.

I have now implemented a demo for the previously proposed <itext> element. During the development process, the specification became more concrete.

I’m sure you’re keen to check out the demo.

Please note the following features of the demo:

  • It experiments with four different types of time-aligned text: subtitles, captions, chapters, and textual audio annotations.
  • It extends the video controls by a menu button for the time-aligned text tracks. This enables the user to switch between different languages for the different tracks.
  • The textual audio annotations are mapped into an aria-live activated div element, such that they are indeed read out by screen-readers; this div sits behind the video, invisible to everyone else.
  • The chapters are displayed as text on top of the video.
  • The subtitles and captions are displayed as overlays at the bottom of the video.
  • The display styles and positions are supposed to be default display mechanisms for these kinds of tracks, that could be overwritten by the stylesheet of a Web developer, who intends to place the text elsewhere on screen.

In order to “hear” the textual audio annotations work, you will need to install a screen reader such as JAWS, NVDA, or the firevox plugin on the Mac.

As far as I am aware, this is the first demo of HTML5 video accessibility that includes support for the vision-impaired, hearing-impaired, and also for foreign language speakers.

There have been initial discussions about this proposal, the results of which are captured in the wiki page. I expect a lot more heated discussion will happen on the WHATWG mailing list when I post it soon. I am well aware that probably most of the javascript API will need to be changed, and also some of the HTML.

Also please note that there are some bugs still left on the software, which should not inhibit the discussion at this stage. We will definitely develop a newer and better version.

I am particularly proud that I was able to make this work in the experimental builds of Opera and Chrome, as well as in Safari with XiphQT installed, and of course in Firefox 3.5.

Screenshot of first itext video player
Screenshot of first itext video player experiment

YouTube Ogg Theora+Vorbis & H.263/H.264 comparison

On Jun 13th 2009 Chris DiBona of Google claimed on the WhatWG mailing list:

“If were to switch to theora and maintain even a semblance of the current youtube quality it would take up most available bandwidth across the Internet.”

Everyone who has ever encoded a Ogg Theora/Vorbis file and in parallel encoded one with another codec will have to immediately protest. It is sad that even the best people fall for FUD spread by the un-enlightened or the ones who have their own agenda.

Fortunately, Gregory Maxwell from Wikipedia came to the rescue and did an actual “YouTube / Ogg/Theora comparison”. It’s a good read and a comparison on one video. He has put his instructions there, so anyone can repeat it for themselves. You will have to start with a pretty good quality video though to see such differences.

Sites with Ogg in HTML5 video tag

Yesterday, somebody mentioned that the HTML5 video tag with Ogg Theora/Vorbis can be played back in Safari if you have XiphQT installed (btw: the 0.1.9 release of XiphQT is upcoming). So, today I thought I should give it a quick test. It indeed works straight through the QuickTime framework, so the player looks like a QuickTime player. So, by now, Firefox 3.5, Chrome, Safari with XiphQT, and experimental builds of Opera support Ogg Theora/Vorbis inside the HTML5 video tag. Now we just need somebody to write some ActiveX controls for the Xiph DirectShow Filters and it might even work in IE.

While doing my testing, I needed to go to some sites that actually use Ogg Theora/Vorbis in HTML5 video tags. Here is a list that I came up with in no particular order:

I’m sure there’s a lot more out there – feel free to post links in the comments.

Firefox plugin to encode Ogg video

Michael Dale just posted this to theora-dev. Go to one of the given URLs to install the Firefox plugin that lets you transcode video to Ogg using your Web browser.

Firefogg is developed by Jan Gerber and lives at There is a javascript API available so you can make use of Firefogg in your own Website project to allow people to upload any video and transcode it to Ogg on the fly.


On Fri, Jun 5, 2009 at 7:08 AM, Michael Dale wrote:
> I mentioned it in the #theora channel a few days ago but here it is with
> a more permanent url:
> &
> These will be simple links you can send people so that they can encode
> source footage to a local ogg video file with the latest and greatest
> ogg encoders (presently thusnelda and vorbis). Updates to thusnelda and
> possible other free codecs will be pushed out via firefogg updates 😉
> Pass along any feedback if things break or what not.
> I am also doing testing with “embed” these encoder interface. For those
> familiar with jQuery: an example to rewrite all your file inputs with
> firefogg enhanced inputs: $(“input:[type=’file’]”).firefogg() … Feel
> free to expeirment based on those examples. The form rewrite has mostly
> only been tested in the mediaWiki context:
> but with minor hacking should work elsewhere 🙂
> enjoy
> –michael
> _______________________________________________
> theora mailing list

FOMS 2009: video introductions available

In January this year we had the third Foundations of Open Media software workshop for developers. The focus this year was on legal issues around codecs, Xiph and Web video (HTML5 video and video servers), authoring/editing software, and accessibility. Check out the complete set of areas of concern and community goals that we decided upon.

As every year, at the beginning of the workshop every participant provided a 5 min introduction about their field of speciality and the current challenges. These are video recorded and shared with the community.

The videos and accompanying slides have been available for about 2 months now, but I haven’t gotten around to blogging about it – apologies everyone! So, here are your star videos in reverse alphabetic order published using open source video software only:


Progress on captions for HTML5 video

Paul Rouget this week published another example implementation for using srt with HTML5 video with a javascript library. This is at least the fourth javascript implementation that I know of for attaching srt subtitles to the video element.

It is great to see such a huge need for this. At the same time I am also worried about the amount of incompatible implementations of this feature. It will inhibit search engines from realising which text relates to and describes a particular video. It will also inhibit accessibility technology such as screen readers or braille devices from realising there is text that would be necessary to be rendered.

A standard means of associating srt (or other format) subtitle files with the video tag is really necessary. So, where are we at with this?

Recently, Greg Millam from Google posted a proposal to WHATWG, that shares a lot of elements with the proposal that has been previously discussed between Mozilla, Xiph, and Opera, the current state of which is summarised in the Mozilla wiki. No implementation into a Browser has been made yet, but initial implementations in javascript exist. I think that we will ultimately come out with a harmonised solution between the browser vendors. It just needs implementation work and continuous improvement.

At the same time, in-band captions that come multiplexed within the Ogg file are also being progressed. At Xiph we are now focusing on using Ogg Kate for these purposes – it really don’t make much sense to invent another codec when Ogg Kate is already so close to solving most problems. So, between the developer of Ogg Kate and myself, we are preparing a Google Summer of Code project that should see a implementation for Firefox 3.1 that is capable of extracting the text from an Ogg file that has a Kate track and displaying that track as though it was a srt file. If you are interested, shoot me an email!

UPDATE: Firefox 3.1 is apparently now called Firefox 3.5 – sorry guys. 🙂

ANOTHER UPDATE: My post seemed to imply that Firefox 3.5 will have Ogg Kate support. This is not the case. There is a patch for Firefox and liboggplay to provide Ogg Kate support into Firefox and this patch will be the basis of the Summer of Code project. The student will then work mostly on implementing a comprehensive javascript library to display Ogg Kate encoded time-aligned text (read: captions, Karaoke etc) in the Web browser. This is a proof-of-concept and a first step towards standardising the handling of time-aligned text in Web browsers that suppor the HTML5 video tag.

FOMS 2009 Awesomeness

I am a slacker, I know – sorry. FOMS happened almost 4 weeks ago and I have neither blogged about it nor uploaded the videos.

So, you will have to take my word for it for the moment: it was a totally awesome and effective workshop that led to a lot of work being started during LCA and having an impact far beyond FOMS.

Every year, the discussions we are having at FOMS are captured in so-called community goals. These are activities that we see as top priorities for open media software to be addressed to improve its use and uptake.

You can read up on our 2009 community goals here in detail. They fall into the following 10 sections:

  1. Patent and legal issues around codecs
  2. Ogg in Firefox: liboggplay
  3. Authoring tools for open media codecs
  4. Server Technology for open media
  5. Time-aligned text and accessibility challenges
  6. FFmpeg challenges
  7. GStreamer challenges
  8. Dirac challenges
  9. Jack challenges
  10. OpenMAX challenges

In this post, I’d just like to point out some cool activities that have already emerged since FOMS.

I’ve already written on the patents issue and how OpenMediaNow will hopefully be able to make a difference here.

Liboggplay provides a simple API to decoding and playback of Ogg codecs and is therefore in use for baseline Ogg Theora support in Firefox 3.1. A bunch of bugs were found around it and the opportunity of having Shane Stephens, its original developer, together with Viktor Gal, its new maintainer, in the same room made for a whole lot of bug fixes. The $100K Mozilla grant towards the work of Xiph developers that was announced at FOMS will further help to mature this and other Xiph software. Conrad Parker, Viktor Gal, and Timothy Terriberry, the Xiph developers that will cut code under this grant, were incidentally all present at FOMS.

The discussion about the need for authoring software support for open media codecs is always a difficult one. We all know that it is important to have usable and graphically attractive authoring tools in order to get adoption. However, looking at reality, it is really difficult to design and implement a GUI authoring tool such as a video editor to a competitive quality. In other areas, it has also taken quite some time to gain good authoring software such as e.g. the Gimp or Inkscape. Plus there is the additional need to make it cross-platform. With video, often the underlying editing functionality is missing from media frameworks. Ed Hervey explained how he extended gstreamer with the required subroutines and included them into the gstreamer python plugin, so now he will be able to focus on user interface work in PiTiVi rather than the underlying video editing functionality.

The authoring discussion smoothly led over to the server technology discussion. Robin Garvin explained how he implemented a server-side video editor through EDLs. Michael Dale showed us the latest version of his video editor in the Mediawiki Metavid plugin. And Jan Gerber showed us the Firefogg Firefox plugin for transcoding to Ogg. Web-based tools are certainly the future of video authoring and will make a huge difference in favor of Ogg.

Then there was the accessibility discussions. During FOMS I was in the process of writing up my final report on the Mozilla video accessibility project and it was really important to get input from the FOMS community – in particular from Charles McCathyNevile from Opera, Michael Dale from Metavid/Wikipedia/ and Jan Gerber. In the end we basically agreed that a lot of work still needs to be done and that a standard way of providing srt support into HTML5 through Ogg, but also out-of-band will be a great step forward, though by far not the final one.

The remaining topics were focused discussions on how to improve support, uptake or functionality of specific tools. Peter Ross took FOMS concerns about ffmpeg to the ffmpeg community and it seems there will be some changes, in particular an upcoming ffmpeg release. Ed Hervey took home a request for new API functions for gstreamer. Anuradha Suraparaju talked with Jan Gerber about support of Dirac in firefogg and with Viktor Gal about support in liboggplay. Further, the idea of libfisheye was born to have a similar abstraction library for Ogg video codecs as libfishsound is for Ogg audio codecs.

As can be seen, there are already some awesome outcomes from FOMS 2009. We are looking forward to a FOMS 2010 in Wellington, New Zealand!

News from the open media world

Today, there were so many news that I can only summarise them in a short post.

The guys from Collabora have announced that they are going to support the development of PiTiVi – one of the best open source video editors around. They are even looking to hire people to help Christian Schaller, the author of PiTiVi. The plan is to have a feature-rich video editor ready by April next year that is comparable in quality to basic proprietary video editors.

The BBC Dirac team have today announced a ffmpeg2dirac software package, which is built along the same lines as the commonly used ffmpeg2theora and of course transcodes any media stream to Ogg Dirac/Vorbis. With Ogg Dirac/Vorbis playback already available in vlc and mplayer, this covers the much needed creation side of Ogg Dirac/Vorbis files. Dirac is an open source, non-patent-encumbered video codec developed by the BBC. It creates higher quality video than Theora at comparable bitrates.

The FOMSFoundations of Open Media Software hacker workshop for open media software announced today the current list of confirmed participants for the January Workshop. It seems that this year we have a big focus on open video codecs, on browser support of media, on open Flash software, and on media frameworks. It is still possible to take part in the workshop – check out the CFP page.

Finally an important security message: Mozilla has decided to put a security measure around the HTML5 audio and video elements that will stop them from being exploited by cross-site scripting exploits. Chris Double explains the changes that are necessary to your setup to enable your published audio or video to be displayed on domains that are different to the domain on which these files are hosted.

FOMS submission deadline extended

The Foundations of Open Media Software workshop has just extended its deadline for submission of registrations requests with travel sponsorship.

FOMS addresses hot topics – such as the new <video> and <audio> tags in HTML5, the uptake and development of open video codecs like Ogg Theora, BBC’s Dirac and SUN’s OMS codec and their native support in Firefox, open audio & media frameworks and players such as gstreamer, ffmpeg, vlc or xine, or the standardisation of audio APIs across platforms. Further topics are listed in the CFP.

In previous years, FOMS has stimulated heated technical discussions and amazing new developments in open media software, such as the creation of libsydneyaudio, the uptake of liboggplay, the creation of Xiph ROE, or the creation of the new Ogg CELT codec.

Video proceedings of last years’ workshops are here. There are also community goals that were set in 2008 and 2007 and provide ongoing challenges.

You should definitely attend, if you are an open media software hacker. This is a chance to get to know others in the community personally and clear up those long-standing issues that need a face-to-face to get solved. Also, it’s a great social event not to be missed. As a bonus, you can spend the week after FOMS at LCA, the world-famous Australian Linux hackers conference, and deepen your relationships in the community. Come and join in the fun in January 2009, Summer in Hobart, Tasmania.