Thoughts and Ramblings

General things I find of interest.

Wall•E

Some friends and I went to see Wall•E last night. It is definitely the funniest movie I have seen all year and I’m glad to see that Pixar hasn’t gone too far downhill. I was afraid that Disney would attempt to destroy them, but it seems they haven’t succeeded quite yet.

On the other hand, the movie did have a lot of technical point which were severely wrong.

  • One scene had a space ship traveling through a large sphere of satellites to get away from Earth. You cannot have a sphere of satellites in orbit and expect them to stay up for a year, much less 700. They’d crash into each other and change their orbits.
  • Even with satellites in the same orbit, you cannot have them sitting within a meter of each other for the same reason.
  • Rotating a ship in space doesn’t change the gravity experienced on the ship (to get any gravity in the first place requires creating it yourself, but that’s another issue).
  • The movie shows a spaceship dumping a large chunk of trash into space. While this make be a convenient means of waste disposal, the sheer mass of disposal shown is completely impractical for a space ship of that size. It would have lost it’s entire mass to trash within a year and it was supposed to be there for 700. What happened to conservation of mass?
  • And the biggest issue: I seriously doubt that humans have the ability to trash the planet to the extent shown in the film, even if we wanted to. We just don’t have that kind of an impact on our environment. Besides, even if we did, rather than sending the entire population to space while cleaning up the planet, wouldn’t it be more practical and cheaper to just send up the trash for disposal?

There are a few more issues; but if you ignore the distortion of science and reason, the movie is quite enjoyable. The sad thing is, the movie could have adhered to both science and reason without destroying the major plot points.


Xcode Filling Log Files

If anyone has ever used Xcode, and tried to debug an app through console messages, then they know how annoying this can be without the development tools getting in the way. An example for me is debugging a frontrow plugin, where sometimes it is easier to print debug info to the console rather than the trouble of using a second machine to fire up gdb. Anyway, Xcode is very good at spewing lots of extraneous and effectively useless information to the console log, such as the following: 6/13/08 5:19:17 PM Xcode[32580] Xcode(32580,0xb0103000) malloc: free_garbage: garbage ptr = 0x456bee0, has non-zero refcount = 1 Of the past 4000 messages in the console, over 3500 of these were xcode. That’s including debugging information from my programs. This is one of the most annoying examples of development tools hindering the development they are supposed to enable.


AC3 Passthrough Compatibility Matrix

Since some parts of AC3 passthrough work, and others do not, I decided to create a bit of a compatibility matrix to summarize it. I’ve added the related bug id’s I’ve reported, which have gone unanswered, in parentheses.

The latest version of perian (to be released soon), will choose between using the hack method for passthrough, and Apple’s method. Anywhere labeled “Hack” will never work with Apple’s method, so it is bypassed to avoid their broken code. The hack does not work with all 5.1 receivers. Taking a file format which is not properly framed, and making it into a .mov file will not correct the framing. Likewise, it will not destroy the framing of a properly framed file format.


Rescuing videos from AVI

As I wrote in a previous entry, people have used avi for things which it was never designed.  One of the more notable examples is multi-channel audio bitstreams. In addition, the people who make such files went as far as to do in the completely wrong manner. So, as a result, I looked for a way to rescue data from the avi format so it is actually usable.

Basically, use mkvmerge from mkvtoolnix to convert the avi file to an mkv file. Then, open the file with Perian, and save it as a .mov file. The result is a file which both has the proper framing for AC3 data, and also has the proper frame decode and display information. This means that one can do real AC3 passthrough on avi files. Maybe this will be the ultimate solution.


Java in Xcode

Well, I have had reason with my research to do some Java development. No biggie, Xcode supports Java too, right? Wrong! well mostly. This all came to a head when I downloaded the latest beta of Xcode (which I am only using because these fix a serious performance issue with the non-beta releases). After the last download, I found 4 distinct bugs in 2 hours, and I’m still finding them. Two of these are Java related, so I gave up, and looked for alternatives.