This confuses me, and I hope someone can help me understand it. Why is it when I take footage that is in AVCHD, .MTS format and has been shot onto and fits onto a 32GB SD card, that when I capture it into Final Cut, which transfers it to AIC, it suddenly becomes 120GB of footage on my Scratch drive? I don't understand how or why that happens. Can anyone help?
AIC essentially stores every frame in its entirety, rather than typical compression methods which store key frames and then deltas for the frames in between. Basically, AIC decompresses the video so that it will perform much faster, which makes editing more efficient. It is only an intermediate format, though, as you'll no doubt want your final version to be compressed to a reasonable size.
Don't use those formats but it sounds like the same thing Adobe Premier would do, it "previews" the entire thing, creates uncompressed files, avi I believe it was, on the scratch drive so that editing goes faster, then you save it as whatever you want. It's a few years since I did any serious editing but I remember waiting and waiting for the previews to load, making a tea, going out for a beer, getting laid, coming home, shower, then the previews were ready after filling up a couple of 500gb scratch drives. (*Only slightly exagerating.)
Yeah, it's important to remember that editing in a compressed format is a really bad idea. I want to scream every time I see someone trying to cut MPEG-2 when they have a readily available AVI to use as a source.