Thoughts and Ramblings

A few days ago, I managed to get my AC3 codec to do AC3 passthrough on the AppleTV. It wasn’t that hard once I stopped making stupid mistakes. Now, if you have a video file with AC3 audio along with a dolby digital decoder, you can play it on your AppleTV and enjoy full 5.1 dolby digital surround.

David Conrad later sent me a patch to make it work on PPC based macs. It is annoying not having a decoder to test these things on. I suppose that just adds to the challenge.

Apologies if this is technical, but since I learned something in this experiment, I thought I would write it up:

I remember going to a seminar a few weeks ago delivered by a faculty candidate which discussed the idea of how to get around the branch mis-prediction problem present in microprocessors. Anyway, her idea was to use predicated statements to make the instructions conditional on a comparison which may not have been completed yet. Essentially, when faced with a decision between two routes, the processor starts computation on both before it is even sure which it should take. Then, when the decision is known, it can proceed to throw out the results from the task it should not have started and only keep the results from the other. Her research mentioned using the processor’s internal register renaming system to prevent the results from the two colliding. There is a problem of both processor support as well as compiler support, as well as the fact that the active power in the processor is now increased. From the first two issues, I doubt we will ever see this come to light, especially when such things are already possible: