Thoughts and Ramblings

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.

So, the good folk over at FFmpeg have stared a Hall of Shame. Basically, it is a page of projects which are using FFmpeg in direct violation of its license. The developers have asked that people link to that page, thereby increasing its ranking in Google. Well, here’s my part. Why should I care about this? Simple, if you look at the list of projects using FFmpeg, you will see Perian listed. Some parts of Perian rely so heavily on FFmpeg that it has an entire section in the code base. Going further, some of the Perian developers are contributing back to FFmpeg, so our copyright is being infringed along with many others.

In my previous post, I discussed how to do AC3 passthrough using Perian. Unfortunately, this method is really a hack, and doesn’t work in all situations. There is a better solution though.

Apple has enabled AC3 passthrough with Quicktime. They have enabled it on the AppleTV to support playback of their HD movies. The code for passthrough is even in the latest version of Quicktime on the desktop, but the celebration ends there. Apple has not exposed a method for enabling passthrough on the desktop either through the user interface, or a hidden preference. They have not even exposed a method for developers to use it through Quicktime (I’ve tried).