Help me understand External HDD requiremanets for Video Editing...

[Tim_]

Hello.

I do video editing for a living, and last 2 years I edit 1080p video shot on Panasonic GH2 using many Western Digital (slow, non-RAID) drives such as May Book 5000-5600 rpm. I edit in PP CS6.

I rarely do any multicam editing, more often it is 1-2 cam tops. I do a lot off Magic Bullet Looks and Colorista color correction and grading. Here's an example: http://www.youtube.com/watch?v=WE0BZ_m28VI

BlackMagic Disk Speed Test shows that the current WD drive I use is 55 Mb/s write and 75 Mb/s read. And according to this software I CANNOT EDIT 1080p footage with suck low speeds, only SD (PAL and NTSC)

So how come I succesfully edit all my videos with no problem at all?... Can anybody please explain, what those "predictions" of BM Disk Speed Test actually mean?

There is interesting article by Larry Jordan about hard drive speed for video editing http://www.larryjordan.biz/hard-drive-speed/ in which he explains that one stream of HD video takes aproximately 20 Mb/s to play smoothly. So by this defenition all I need for 1-2 cam videos is 40 Mb/s. Everything on top of that will just speed up transfer files from SD card to HDD, right?

I mean sure, I cannot play back my footage smoothly with lots of heavy effects in full resolution, but so does my friend who have 450 Mb/s SSD for his external media with the same PC as I have... (As far as I understand, correct me if I'm wrong, rendering effects is more GPU job (and other element such as RAM and CPU) then a HDD transfer speed job)

So MY QUESTION IS how do I benefit from buying some fancy RAID external drive like WD Velociraptor Duo or Lacie 2big Thunderbolt, which are 350-250 Mb/s as RAID 0?

250/20=12,5, so does this mean that in order to benefit from those speeds I need to edit 12-cam footage? (I never ever going to do that btw)

 

[Exact]

BlackMagic Disk Speed Test shows that the current WD drive I use is 55 Mb/s write and 75 Mb/s read. And according to this software I CANNOT EDIT 1080p footage with suck low speeds, only SD (PAL and NTSC)

The Black magic speed test is talking about uncompressed footage, not compressed footage. Uncompressed footage needs a much higher bit rate.

So how come I succesfully edit all my videos with no problem at all?... Can anybody please explain, what those "predictions" of BM Disk Speed Test actually mean?

You're editing compressed footage, which requires a lower bit rate to be read from the media.

All you need is media that's fast enough for what you are doing and don't worry about what anyone else is doing.

Where faster media helps is reducing the pause when you hit play and the NLE is trying to buffer enough media to play smoothly. It also helps where you are scrubbing back and forth.

Do you need a fast raid? Probably not. Would you see any difference? Maybe. I have several computers setup with both internal and external raids and also using single external drives. The main difference I see day to day is the start up time when pressing play. With the raid it plays pretty much instantly. With single external drives there could be a perceivable delay. Even half a second difference is easily perceivable.

If you buy a fast raid, usually that means that bottle neck is taken care of and now you'll bump in to the next bottle neck would could be CPU, GPU or even memory bandwidth.

 

[Tim_]

Thank you very much, Exact! This is very clear answer! Helps a lot!