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ProRes 422 and drive speed
Hey folks,
We edit HDV natively, and today I had a long awaited conversation with my boss about not doing that anymore. I’m having trouble understanding the storage math.
Blackmagic Disk Speed Test says the regular old FW 800 drive I’m using now can read at 67.3 MB/s and write at 57.8 MB/s. Those convert to 538.4 Mb/s and 462.4 Mb/s respectively, right?
If 1920×1080 29.97 fps ProRes 422 is 147 Mb/s (as per Apple’s white paper), does that mean my little FW 800 drive can theoretically play back 3 full-res streams? (538.4/147=3.66)
I feel like we need an SATA RAID, but for now these numbers are telling me a bigger FW 800 drive would do. What’s the deal?
Thanks and sorry for the long post,
Zak
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4 Replies
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I’ll wager you can get 2 streams of ProRES 422 and uncompressed 10-bit.
Shane
Littlefrog Post
http://www.lfhd.net -
ProRes, having the same data rate as Avid DNxHD, is about the same speed at uncompress SD. So you will need about 20-30 MB/s per stream depending on format and bit depth.
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The ProRes numbers are similar to uncompressed SD. I edited uncompressed SD on two of the original G-Raid discs striped together. It was a bit dodgy when I tried to make it work with one G-Raid.
As you probably know, all of the firewire ports on you computer share the same bus. My guess is that the HD IO is going to want the Firewire bus to itself. If you decide on FW800, I recommend that you buy a firewire expansion card from Sonnet or someone similar.
A SATA RAID is probably a better idea, if you can afford it.
Here are a couple of articles that might help
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It should be possible to record and playback 1080i 60 on a single SATA drive… now that is pretty amazing I think. However… you’ll get a lot more streams on faster drive setups such as an array, and you’ll get more streams with more cores on your machine.
Think of it this way: it’s the same data rate as uncompressed SD… however it’s more efficient. In fact if you add more cores to your Mac (such as an 8 core machine) you’ll get even more streams in RT because the processors draw the video twice as fast as a quad, and 4 times faster than a dual at the same speed… pretty amazing. So faster drives will still give you something you’d not have with a single.
All that said though, it’s a wonderful addition to FCS. It’s space is about 1/6 the size of uncompressed HD, and so it doesn’t require really fast arrays to work with, however they will provide for more streams simultaineously without rendering.
Jerry
Apple Certified Trainer
Author: “Jerry Hofmann on Final Cut Pro 4” Click here
Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D
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