Category Archives: Open Source Multimedia

News regarding open source multimedia projects.

Serious About VC-1

I have a plan, I really do. I am still working hard on Understanding VC-1. Just so that you, the reader and open source multimedia enthusiast understand correctly, this is not so that we can build a new implementation that mirrors the reference implementation 1:1. What I am doing right now is more or less the “phase 1” of this particular documentation effort. Phase 2 is developing a more top-down specification in a similar spirit as my old VP3 format document. Phase 3 is to generate a development roadmap with specific tasks and milestones as well as a number of sample vectors for individual modules which should facilitate initial component validation as well as ease development of SIMD-optimized components.

So you see, phase 1 is where I essentially use the MultimediaWiki as a scratchpad. VC-1 is, like, really big and hard to get one’s head around. This process is helping me.


Google Logo

Part of my plan in all of this is that I am hoping to pawn off the actual writing of code on other people. I know there are people out there — even people reading this blog — who are interested in making some material contribution to open source multimedia. On Monday I learned of Google’s second annual Summer of Code initiative where, in a nutshell, college students can get paid to work on approved open source projects. Since the project as outlined above, with the roadmap and deliverables/milestones, seems ideal for this mentoring concept, I submitted FFmpeg as a project for consideration, albeit a few hours after the formal deadline for doing so. Since the SoC is quite popular, it’s likely that they have all the projects they need.

However, if a student is out there following this blog and interested in working on a very important piece of open source multimedia work, you will have the opportunity starting May 1 to submit an application to work on a project not listed with an official mentoring organization, per this SoC FAQ entry. It’s a long shot, but Google has sponsored more ambitious stuff.

A big task? You bet. But if you follow this blog you’re probably at least minimally qualified to tackle the project.

Sustainability Of Digital Formats

I was searching for some comprehensive registry of FourCCs when I happened upon Sustainability of Digital Formats: Planning for Library of Congress Collections. They host an interesting, and recently updated, survey of all manner of multimedia formats including containers, video codecs, audio codecs, and text formats.

Also, I eventually found the Microsoft’s official list of registered AVI video FourCCs (and 16-bit audio codec identifiers): The IANA hosts it: http://www.iana.org/assignments/wave-avi-codec-registry. There is some very interesting stuff in there. Did you know that Dolby had an AC2 codec? And that their listed address is spelled incorrectly? (I know since their office is about 2 blocks away from where I work.)

Feeble Files DXA And Wiki Upgrade

Kirben from ScummVM tipped me off on the DXA format. Apparently, it was only ever used in one game called Feeble Files. He reports that the Amiga and Macintosh ports used the DXA format. I was unaware that there were any commercial games for the Amiga past about 1995. Here is the requisite Wiki page on the format. It’s one of the simplest formats yet. It’s unusual in that it stores all of the audio data in a single WAV file chunk near the start. The known video coding format simply uses zlib’s deflate() function to compress a raw frame or the result of a XOR operation between the current and previous frames.

Speaking of the Wiki, I have upgraded the MultimediaWiki to the latest, and therefore greatest, incarnation of MediaWiki — 1.6.3. I don’t see too many major differences so far. There are supposed to be some useful counter-spam features which seems to be increasingly important. I still can’t generate math expressions in Wiki. I’ve traced this to the absence of LaTeX processing utilities on the host machine. Why does LaTeX always have to cause such trouble? We’re stuck with plaintext math expressions until I can get around this problem somehow.