Please Clarify & Help My Brain Regarding HD
 

I have a Canon Powershot; it shoots sublime 720p HD. I use a program called Prism Video Converter that reformats it from a mov.file to mpg. I open it in Vegas, and everything is right with the world. A snap!

I also have a HMC150 that I have yet to use, and recently ordered a mega-computer to process ACHDV, which seems more demanding for editing purposes. I also have Cineform waiting in the wings.

Now, what should I expect with ACHDV that makes it more complex? Why is the HD I use with the Powershot so effortless to convert and edit?

Thanks (I should know the answers to all this but admit defeat)

AVCHD uses a long GOP MPEG compression to achieve the results it does at the bitrates it records at. This requires the MPEG stream to be "unpacked" during playback and modification (editing, effects) as only every keyframe (or "I" frame) contains ALL the information required to make a full frame. This requires a lot of computation, especially given that AVCHD is a "next gen" codec - 5 years from now we will look back and laugh that Long GOP codecs crippled computers but for now, we need raw computing "horsepower" for real time performance.

Thanks; I'm glad I ordered that computer.

1280x720=921,600 pixels per frame
1920x1080=2,073,600 pixels per frame

Right there you have over 2x the amount of data crunching. I've got a couple little P&S cameras that shoot pretty nice 720p video as well, but it's not as sharp as a camera shooting 1080, just aren't as many pixels dancing around!