Author Archives: Multimedia Mike

The Visibility Phase

Do me a favor– check out my new experimental prototype of the FATE front page, one in which results are available immediately after they are logged by a build machine (no up-to-15-minute cache delay). There is a lot it doesn’t do yet. And of course, I’m still terrible at web development, so it’s still hideous and awkward. However, it is now possible to freely sort the build/test results by 3 criteria– the default is to sort by failed builds first, then by ascending “tests passed” numbers, and then by architecture. No particular reason for that last default, but the first 2 are intended to illustrate immediately where the current problems lie within the FFmpeg codebase. Since the criteria are specified through the URL via a GET request, you can easily bookmark your favorite sort order. In the future, I hope to send out a cookie so that the main page at least remembers what your last sort order was.

Let me know if I’m on the right track with this.

Very basic TODO: When selecting new criteria, make sure the list boxes are preset to those chosen criteria rather than the global defaults. (I told you I’m bad at this.)

FATE in the RAW

Check this out: a CSV file containing the latest FFmpeg build/test results as aggregated by FATE. The file reflects the latest results as soon as they are entered into the database — none of that “waiting up to 15 minutes for a cache refresh” business.

I have finally implemented the first 3 of the 4 steps outlined in this post describing how to make FATE prettier and more useful. I look forward to redesigning the front page to really improve matters. Unfortunately, when I deployed this new caching mechanism on the live system last night, a new problem manifested on some of my machines where the results were not being transported to the server speedily– the receiving script would time out or just take a really, really long time to respond (think on the order of 5-15 minutes when it normally takes no longer than 2 seconds at the extreme). So I’m guessing I will need to investigate that soon, perhaps before the front page redesign, though it may have just been a transient problem on the server side.

The raw.php file linked above isn’t supposed to be particularly useful for the purpose of human consumption. However, if anyone wants to use it for creating other services, that might be interesting.

FATE on Twitter?

For the most part, I haven’t been able to abide the notion of Twitter, where people “micro-blog” little messages of up to 140 characters each. It just seems like a bunch of “look at me” nonsense with no real purpose. But then, I used to think the same about blogs in general until I found a few interesting blogs. Lately, I have finally found a few interesting people to follow on Twitter.


Twitter logo

Then I read mentions of “Twitter clients” and quickly realized that there is an entire software ecosystem around these little messages. Indeed, there is an officially sanctioned HTTP/REST-based API for writing your own client apps.

Naturally, where I’m going with this is: Would it be useful to adapt FATE to post, ahem, “tweets” regarding state transitions (something either broke or got fixed with an individual build)? Would anyone care, i.e., does anyone already actively follow Twitter? I’m getting close to the point where I believe I can implement an email notification system, most likely to a separate mailing list. But this new channel might not be too difficult to implement at the same time. (Actually, I’m still trying to figure out from the documentation whether or not it’s possible to post a new message through the API; I can’t find the right function, or perhaps I just don’t understand all the Twitter-specific jargon yet.)

This is a little more outlandish, but as I was looking at a list of tweets today, I suddenly wondered about the possibility of sending encrypted messages through such a channel. I’m not the only person who was curious. This person beat me to the brainstorm, even going so far as to hack up a proof of concept that encodes a message of arbitrary length into multiple tweets.

Reverse Engineering Math Formulas

Even though I have been studying and working on multimedia technology since 2000 — reverse engineering, documenting, and reimplementing a variety of audio and video codecs — I didn’t actually begin to understand why various algorithms achieved their compression until about 2003. I’m just like that — I study the practice first, and then the underlying theory eventually becomes clear to me (maybe; it has been 9 years and I still couldn’t explain everything about the discrete cosine transform if you asked).

I happened to be looking back over the ZMBV (DOSBox) video codec today. Continue reading →