HDV vs AIC speed test

[matteusclement]

So After being in these forums for a while, I was juggling between AIC and HDV from my Canon HV30. From what I had read, HDV was compressed and AIC was not. This in theory made AIC a better choice for rendering/output over HDV as the CPU was busy not going to be busy "decoding" the HDV and then outputting it. So the theory goes....

After a little trial and error on this one, I have found that AIC doesn't seem to do this. GRANTED, I am using external FW 400 drives for my media and my guess is that AIC's large HD footprint is what is really slowing me down. FYI: I use a intel iMac with 4 gigs ram along with said externals.

So I guess this is a post just for some information, but does anyone have anything to say about this? Is my experiment flawed?

 

[TheStrudel]

In a word, yes.

HDV does take more CPU and system resources to play back in real time. But you're ignoring the biggest speed bottleneck in most modern computer systems: storage. It's also worth pointing out that AIC is also very compressed, just not compressed using the interframe long GOP structure that HDV does, which is more efficient but far slower to conform or render.

AIC always handled faster on my machine and was more responsive than HDV. As you already know, it takes up far more space than an equivalent amount of HDV video. When you access, say, a 2 minute clip by scrubbing through it rapidly, the same clip amounts to far more space which has to be transferred in the same period of time when using AIC. So your guess is absolutely correct. You're constrained by both the speed of the hard drives and the relatively slow Firewire 400 bus (yes, FW800 makes a difference with drives that are fast enough).

When I'm scrubbing or dealing with a lot of footage, the hard drive is always, always what slows me down. I'm using a Mac Pro with 8 2.8 ghz cores and 10 GB of RAM, more than FCP can actually address. I'm always waiting for HDDs to catch up, and whenever I see a spinning ball, I'm hearing them kick into high gear.