ginger's thoughts

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.

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

During last week’s LCA, Jan Gerber, Michael Dale and I gave a 3 hour tutorial on how to publish HTML5 video in an open format.

We basically taught people how to create and publish Ogg Theora video in HTML5 Web pages and how to make them work across browsers, including much of the available tools and libraries. We’re hoping that some people will have learnt enough to include modules in CMSes such as Drupal, Joomla and Wordpress, which will easily support the publishing of Ogg Theora.

I have been asked to share the material that we used. It consists of:

• HTML5_Tutorial (611KB)
• the example videos (328MB), and
• HTML5 video exercises (3.4KB).

Note that if you would like to walk through the exercises, you should install the following software beforehand:

• oggz-tools
• oggvideotools
• apache2 or a Web server of your choice
• ffmpeg2theora
• firefox3.5+
• firefogg plugin
• firebug plugin
• vlc, mplayer, totem or xine
• kino or pitivi or another video editor that exports Theora, e.g. iMovie with XiphQT

You might need to look for packages of your favourite OS (e.g. Windows or Mac, Ubuntu or Debian).

The exercises include:

• creating a Ogg video from an editor
• transcoding a video using http://firefogg.org/
• creating a poster image using OggThumb
• writing a first HTML5 video Web page with Ogg Theora
• publishing it on a Web Server, with correct MIME type & Duration hint
• writing a second HTML5 video Web page with Ogg Theora & MP4 to cover Safari/Webkit
• transcoding using ffmpeg2theora in a script
• writing a third HTML5 video Web page with Cortado fallback
• writing a fourth Web page using “Video for Everybody”
• writing a fifth Web page using “mwEmbed”
• writing a sixth Web page using firefogg for transcoding before upload
• and a seventh one with a progress bar
• encoding srt subtitles into an Ogg Kate track
• writing an eighth Web page using cortado to display the Ogg Kate track

For those that would like to see the slides here immediately, a special flash embed:

Enjoy!

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.

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

FOMS (Foundations of Open Media Software workshop) at
http://www.foms-workshop.org/foms2010/pmwiki.php/Main/CFP

LCA Multimedia Miniconf at
http://www.annodex.org/events/lca2010_mmm/pmwiki.php/Main/CallForP

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.

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.

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:

• Viktor Gal, Xiph / Annodex liboggplay
• Timothy Terriberry, Xiph – Theora codec
• Silvia Pfeiffer, Annodex/Xiph – video a11y
• Shane Stephens, Google – liboggplaya
• Robin Gareus, linuxaudio.org
• Rob Savoye, Gnash
• Peter Ross, Xvid & FFMpeg
• Michael Dale, Wikipedia & Metavid
• Jan Gerber, Xiph hacker
• Edward Hervey, Collabora – PiTiVi
• Conrad Parker, Annodex/Xiph hacker
• Charles McCathieNevile, Opera
• Benjamin Otte, swfdec
• Anuradha Suraparaju, BBC – Dirac codec

Enjoy!

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/Archive.org 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!