Hard drive for 4K workflow?

[Mike 50]

Greetings everybody. I can imagine how excited everyone must be about the Red. It's sort-of like a milestone in history.

Anyway, I have a quick question....

I realize to capture uncompressed RAW you need a hard drive that can write at 323MB/s. There is REDCODE, only 27MB/s. But, when you eventually decompress it to DPIX/TIFF/MPEG, do all the post work - then:

Do you still need a hard drive that can read at 323MB/s to let's say laser-print to 35mm?

Can you get away with a SATA drive instead of a Fiber Chanel/SCSI which cost 10x more?

Also, if anyone knows; What type of cable does RED output with (in uncompressed RAW)?

Thank you.

[David Newman]

323 MB/s is for 12-bit uncompressed bayer RAW, a 16-bit per channel RGB image in TIFF/DPX etc. is 4 times bigger. At 1.26GB/s not expect to playback 4K DPX files on your workstation.

[Rob Lohman]

EDIT: THE FOLLOWING NUMBERS ARE INCORRECT, SEE THE NEXT 2 POSTS

Our uncompressed RAW port is an optical port. It's not something you can easily pipe into something else to record. Hence our product RED-RAID.

You do not *need* 323 MB/s or faster "drive", unless you want to do things with that stream in real-time.

If you have the money to laser-print I would say a fast SAN/NAS system should not be much of a problem :)

If you want/need a cheaper option I would think about getting SAS (Serial Attached SCSI) or SATA drives together with a PCI express RAID board that lets you hook up say 24 drives.

Shooting 4096 x 2304 at 24 fps in 16-bit (padding 12-bit) gives 432 MB/s
Shooting 4520 x 2540 at 24 fps in 16-bit (padding 12-bit) gives 526 MB/s

DPX is a format that can pack these bits together without wasting so much space. Assuming you output in some 10-bit space you would need for DPX:

4096 x 2304 at 24 fps in 10-bit DPX: 270 MB/s
4520 x 2540 at 24 fps in 10-bit DPX: 329 MB/s

The overhead for the DPX file format is *NOT* included in these calculations.

Again, if this is solely for laser-printing you might not need this speed. I looked up the ARRILASER: http://www.arri.com/prod/digital/arrilaser/index.php

< 2.9 seconds per 4K frame (1:1.85)
< 3.8 seconds per 4K frame (full ap)

So let's say you crop your resolutions to 1.85:

4096 x 2214 for 10-bit DPX is around 11 MB per frame
4520 x 2444 for 10-bit DPX is around 14 MB per frame

They say it's under 2.9 seconds. It's a weird number to give so I'm assuming they mean it'll be around 2.8 seconds per frame. Then you need a data rate of 11 / 2.8 = 4 MB/sec or 14 / 2.8 = 5 MB/sec, excluding over head.

Not really spectacular :) Obviously faster lasers printers may exist (I'm by no means an expert on laser printing). 2K printing is also faster, but still nowhere near real-time on that ARRILASER, for example.

[Lucas Wilson]

...
4096 x 2304 at 24 fps in 10-bit DPX: 270 MB/s...


Hi Rob...

Are you talking about RAW or DPX? I may be misunderstanding something (entirely possible...,) but take a look.

4096 * 2304 = 9,437,184 (number of pixels in the file)

9,437,184 * 32 = 301,989,888 (number of bits in the file - each pixel = 32 bits in a 10-bit DPX file)

301,989,888 / 8 = 37,748,736 (number of bytes in the file)

37,748,736 / 1,048,576 = 36 (number of megabytes in the file)

So each 4096*2304 10-bit DPX = 36 MB/frame.

36 * 24 = 864

So realtime playback of that 10-bit DPX sequence would need 864 MB/s.

Cheers,

Lucas
-----
ASSIMILATE, Inc.
Los Angeles

[Rob Lohman]

D'oh! Must've still been sleeping, thanks Lucas. All those numbers get confusing.

Okay, so here are the proper numbers then (hopefully):

4096 * 2304 at 24 fps in 10-bit RGB DPX = 864 MB/s
4520 * 2540 at 24 fps in 10-bit RGB DPX = 1051 MB/s

In the 1.85 aspect ratio:

4096 * 2214 as a 10-bit RGB DPX frame = 35 MB
4520 * 2444 as a 10-bit RGB DPX frame = 42 MB

At 2.8 seconds per frame for laser printing that's 12.5 MB/s & 15 MB/s

[Mike 50]

Okay, so basically you don't need a faster drive to transfer from RED RAID to your own RAID SAN? Even if your SAN is SATA?

[Rob Lohman]

Not sure what you mean with "a faster drive". The slowest part in the link will determine speed you're getting.

[Mike 50]

You know how when you capture a DV tape from a camcorder to your computer over USB - it's in real time?

Is it like that with a RED RAID? Because if it's real time capture you would in theory need a RAID that could write at 323MB/s for RAW.

[Mike 50]

Our uncompressed RAW port is an optical port. It's not something you can easily pipe into something else to record. Hence our product RED-RAID.

You do not *need* 323 MB/s or faster "drive", unless you want to do things with that stream in real-time.

Actually I guess this answers my question.

[Thomas Mathai]

You would definitely want a SAN solution, but if you want to go laser print to film, then you just deliver a big firewire drive to the post house you will be using.

[Petr Dvorak]

flash drives are just coming - SSD (Solid State Drive), 62MB/s, 1ms :)

http://www.tgdaily.com/2007/01/17/adata_ssd_128gb/
http://www.theinquirer.net/default.aspx?article=36841

[Rob Lohman]

Reading tends to be faster than writing. So you can expect to read faster than real-time off the RED-RAID. How much remains to be seen. Obviously the system is designed for full 4.5K @ 60 fps. If you record 2K or lower frame rates you're storing smaller files which will also transfer faster.

It's a bit early to start talking about RED-RAID details. We're focussed on the camera, monitoring, RED-DRIVE, REDFLASH etc. first.

[P Andersson]

does it need to be smaller and faster than this 500kb drive from 1975?

http://www.boingboing.net/2005/11/11/500kb_of_hard_drive_.html

http://www.reduser.net/forum/uploaded/251_1169504199.jpg

[Andrew Benz]

Ah Agwah, the first transportable ipod. What was the tag line? Oh yeah---"One Song, One Drive.... Be One." ...memories

[Mike 50]

LOL, look at that hard drive!