Monday, 21 January 2008

On the road to a Dirac standard ... at last

Ok, so I know that people think that Dirac disappeared into a black hole some while ago but we're still hanging in there and getting it done. We're just coming up to some really major milestones and things are looking really exciting.

First, Dirac (or part of it) is going to be an international standard. Yay! We made a cut-down version doing intra coding only and this has only just been submitted to the SMPTE. If it goes through it will become VC-2 (Windows Media 9 became VC-1 when they standardised it). After a lot of hard work fighting SMPTE's preferred Word format (yuk) it went in just before Christmas and is being voted on as a Committee Draft as I write this.

At the same time we've been updating the full spec and that's been published today. Version 1.0 covers the professional VC-2 stuff, whilst version 2.0 covers the whole system. If VC-2 is well-received we'll propose an extension so that it covers the whole of Dirac. Then at last there'll be a royalty-free video compression standard ...

There'll be a new release (0.9) of the Dirac reference software in the next couple of days to comply with the spec. The compression performance of the reference encoder keeps improving and we'll carry on adding tools in later spec versions (3.0 etc) so that it stays as competitive as possible.

The second really exciting thing is that Dave Schleef has been going great guns on the Schrodinger (NB the code is no longer in SVN - it's available from git clone git: //diracvideo. schleef. org/git/schroedinger.git) high-speed implementation of Dirac. This really is very fast and Wladimir van der Laan is doing great things to make it even faster with a CUDA implementation some of which Dave is merging in. Dave is getting really close to a 1.0 release that will be fast enough for realistic use for encoding and decoding.

The third thing is that our hardware partner Numedia have produced some Dirac hardware using the low-delay syntax. This isn't the stuff of streaming video but it allows the BBC and other broadcasters to re-use all our SD infrastructure to carry HDTV transparently, with almost no delay (so no audio sync cock-ups in production).

So it's been a long haul (the first software was released in 2004, although it feels like a decade ago) but we're getting there.

Thomas

12 comments:

djp said...

Congratulations on your perseverance and amazing work so far. I am both a linux geek and a filmmaker and dirac has had me all excited since it's first announcement. As someone who understands how open source development works, and how important this codec is, I have faith that your team has what it takes, and dirac will indeed have a bright future benefiting all of us.

thank you,
David J Patrick,
CEO/ Janitor
linuxcaffe.ca

Saoshyant said...

The article mentions the encoder. I'm curious: does it encapsulate it directly in Ogg? And if so, is it using the new file extension for all video on Ogg, which is .ogv?

Anonymous said...

That is quite exciting. If it gets through the standardization process, maybe it could even warrant an update to the project front page? :)
Some benchmarks showing speed, compression ratio and image quality of current implementations would be nice to have with a news release. Even very informal tests would be helpful in giving a ballpark estimate of feasibility for a project.

Anonymous said...

We made a cut-down version doing intra coding only and this has only just been submitted to the SMPTE.

Just curious, why this limitation to intra coding only in the proposed standard? Doesn't it severely limit the amount of compression it can achieve?

Anonymous said...

Thomas, congratulations to this major achievement. I'm an Ogg Theora user since its first alpha, and the prospect of another, more advanced open video codec is really exciting to me! All the best, Jörn

Anonymous said...

Re question about why intra coding:

In a studio environment you need minimal delay, so you can't afford to buffer several frames in order to build up a GOP before passing it on. Sticking to intra also simplifies the codec, and you can cut between sources at any frame boundary without scrambling the picture.

Moreover, you don't need a huge amount of compression if you want to do things like getting an HD signal down an existing SD SDI cable you've previously installed. Not only can Dirac Pro do this, but it's clever enough that if you plug the compressed feed into a standard definition SDI monitor, you'll even see a recognisable picture. This allows you to use what is to hand to see what's coming down the wire. Again, a very useful thing to be able to do in a studio.

For more explanation see http://www.bbc.co.uk/rd/projects/dirac/diracpro.shtml

Anonymous said...

Congratulations on the progress. I'm excited about Dirac and what it will bring to Free and Open communications.

Marco Radossevich said...

Just a suggestion: why Dirac could'n become an EU public broadcasters standard ?

Italian RAI uses Real Codec !!!

I live in Italy and I really don't like to give my money (we must pay an annual subscription for the public televisions, here) to closed-patented codecs.

Marco
--
>>Forward Agency
In progress we (always) trust.

Adam Luebke said...

The word "Dirac" got me fired up. I love that man and his brilliance/quirkiness. He appears in some of my writings. I also have written a book of poetry about him.

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