Jump to content


Photo

Major differences between 10-bit uncompressed 1080p and 2K DI?


  • Please log in to reply
6 replies to this topic

#1 Wai Choy

Wai Choy
  • Basic Members
  • PipPip
  • 29 posts
  • Student

Posted 31 August 2007 - 10:25 AM

Hi,

I'm in preproduction for my thesis short, which I'll be shooting on Super 35 3-perf.

In the past, I've transferred my negatives to 10-bit uncompressed 1080p and I'm wondering if you'd be able to fill me in on a few questions I have about it and 2K DI.

1. In terms of image quality, what are the noticeable differences between the two?

2. Since both transfers are done on the Spirit 2K, is the transfer time the same and are the costs the same?

3. What is the file format for 2K DI footage, and can it be edited in Final Cut Pro Studio 2?

4. In terms of printing from digital back onto 4-perf 35mm for projection, how close are each of the two formats to the image quality of the original negative?

Thanks a lot for your help!

-Wai
  • 0

#2 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11937 posts
  • Other

Posted 31 August 2007 - 12:33 PM

> 1. In terms of image quality, what are the noticeable differences between the two?

Very little. If you were shooting scope, you might do slightly better on the 2K if only because it's likely to be a 2:1 anamorphic image in itself, so you will be using the full vertical resolution of a 2048x1536-pixel frame. But you're not. So, not much.

> Since both transfers are done on the Spirit 2K, is the transfer time the same and are the costs the same?

No. The only Spirits I've ever seen do data transfer did it at about 15fps, which may or may not be a limitation in the telecine itself, but is certainly a limit of dual-link HD-SDI. Given that it therefore takes much longer, it's going to cost you more, even if they don't charge more for the base service.

> 3. What is the file format for 2K DI footage, and can it be edited in Final Cut Pro Studio 2?

Usually DPX sequences. Not sure about FCP - I'd presume so.

> 4. In terms of printing from digital back onto 4-perf 35mm for projection, how close are each of the two
> formats to the image quality of the original negative?

Original camera negative with reasonably slow stock will outresolve 2K DI, by a bit. Graininess in faster stocks can start to overwhelm the visible resolution of the thing. But the question you seem to be asking is about the technical difference between the two, and that's more down to how it's likely to be handled than differences in the information that's being recorded.

Phil
  • 0

#3 Michael Most

Michael Most
  • Basic Members
  • PipPipPipPip
  • 765 posts
  • Other

Posted 31 August 2007 - 06:09 PM

> Since both transfers are done on the Spirit 2K, is the transfer time the same and are the costs the same?

No. The only Spirits I've ever seen do data transfer did it at about 15fps, which may or may not be a limitation in the telecine itself, but is certainly a limit of dual-link HD-SDI. Given that it therefore takes much longer, it's going to cost you more, even if they don't charge more for the base service.


This is not the case. The Spirit 2K does 2K at 24fps, real time, when coupled with a GSN data interface and a Bones controller system. In this mode, it does not use dual link HD-SDI as a transport. But even if you did use dual link, that doesn't present any problem with real time transport of 2K, provided your definition of 2K is 2048x1080 - which is basically DCI spec 2K for 1.85 projection (within a couple of pixels). In fact, that's how DLP Cinema projectors are usually fed. The Spirit 2K in data mode produces 2048x1556, full frame 1.33:1, but can produce other aspect ratios when it's specifically set up for it. The reason scanning on a Spirit 2K usually costs more than HD telecine transfer on the same machine is because you need to use a data interface that's pricey, you have to store the DPX files somewhere that can accept real time 2K transfer rates, and then you have to copy those files to a client drive, which takes quite a bit of time.

> 3. What is the file format for 2K DI footage, and can it be edited in Final Cut Pro Studio 2?

Usually DPX sequences. Not sure about FCP - I'd presume so.


Not natively. Final Cut is a Quicktime application. It understands Quicktime and only Quicktime for motion sequences. You can, however, use some third party tools like Gluetools to trick it into thinking that your DPX sequences are actually Quicktime files. But when it renders them - which it will have to do for anything that has any kind of effect or transition on it - it's going to do it in 8 bits - not something you want in a DI situation, which is one reason why most DI facilities don't use it for this purpose.
  • 0

#4 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11937 posts
  • Other

Posted 01 September 2007 - 08:27 AM

> This is not the case. The Spirit 2K does 2K at 24fps, real time, when coupled with a GSN data interface and a Bones controller system.

I was aware of the existence of a pure data interface for Spirit, but I've never actually set eyes on one!

> In this mode, it does not use dual link HD-SDI as a transport. But even if you did use dual link,
> that doesn't present any problem with real time transport of 2K, provided your definition of 2K is 2048x1080

Yes, although that isn't my definition of 2K if he's shooting for a scope result (which he might or might not be).

Phil
  • 0

#5 Keith Mottram

Keith Mottram
  • Sustaining Members
  • 824 posts
  • Other

Posted 01 September 2007 - 10:46 AM

Not natively. Final Cut is a Quicktime application. It understands Quicktime and only Quicktime for motion sequences. You can, however, use some third party tools like Gluetools to trick it into thinking that your DPX sequences are actually Quicktime files. But when it renders them - which it will have to do for anything that has any kind of effect or transition on it - it's going to do it in 8 bits - not something you want in a DI situation, which is one reason why most DI facilities don't use it for this purpose.


actually this is not true. with both blackmagic and kona boards capable of 2k (kona 3 for example) you can put a 2k 4:4:4 rapper around the dpx's and edit them in fcp. though you would only want to do that if you were nuts. instead the best idea would be to to transcode into compressed codec edit and then reconect to the dpx files in color when you would grade the dpx files directly. this would be spanking and you would grade in 32 bit float. with all the hardware and software and monitor rental you would need for the price of a few days in a top d.i suite. just don't scrimp on the 'color'- ist.

keith
  • 0

#6 Michael Most

Michael Most
  • Basic Members
  • PipPipPipPip
  • 765 posts
  • Other

Posted 01 September 2007 - 02:41 PM

...reconect to the dpx files in color when you would grade the dpx files directly. this would be spanking and you would grade in 32 bit float. with all the hardware and software and monitor rental you would need for the price of a few days in a top d.i suite. just don't scrimp on the 'color'- ist.


Then why not go to the DI suite, where you not only get significantly better monitoring - with proper calibration for the output format you're targeting, whatever that is - but you also get a top-notch colorist who's much more familiar with the environment, the equipment, the problems, the workflow, and the nuances of color correction than you probably are?

The fact is that unless you're willing to spend about $80,000 on a projector, and create a proper screening environment, and truly understand how to manage a color calibration path, you're NOT getting "all the hardware and software and monitor rental" you get when you walk into a room designed for the purpose, and staffed by someone who does it for a living. Depending on the level of your project, that might or might not be important to you, however.

Also, if you go the Color path, you must ultimately render the clips in the timeline and then return to Final Cut to create deliverables and render whatever transitions you might have. As soon as you do this, you're back to Final Cut's 8 bit render path for anything other than YUV. The only way to avoid this is to create all effects - and this means transitions, fades, title overlays, anything - in another program, like After Effects. You're getting into a very convoluted finishing path by working this way. The only justification I can think of for it is that you're doing a purely personal project and have no money to spend - other than what you need to spend to acquire Final Cut, After Effects, a fast Mac to run them on, and lots of very fast storage.
  • 0

#7 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11937 posts
  • Other

Posted 01 September 2007 - 04:08 PM

> Then why not go to the DI suite...

Because it costs seven hundred dollars an hour.

Everything you have said is true. Whether it's a good application of funds or not is a matter of opinion.

Phil
  • 0


Tai Audio

Ritter Battery

Gamma Ray Digital Inc

Visual Products

Media Blackout - Custom Cables and AKS

Glidecam

Technodolly

Broadcast Solutions Inc

Rig Wheels Passport

Abel Cine

Willys Widgets

Metropolis Post

The Slider

Aerial Filmworks

Paralinx LLC

CineTape

CineLab

Opal

FJS International, LLC

rebotnix Technologies

Wooden Camera

Tai Audio

Media Blackout - Custom Cables and AKS

Broadcast Solutions Inc

Wooden Camera

Paralinx LLC

Technodolly

FJS International, LLC

rebotnix Technologies

Abel Cine

Glidecam

CineLab

Visual Products

Rig Wheels Passport

CineTape

Aerial Filmworks

Gamma Ray Digital Inc

Metropolis Post

Opal

Willys Widgets

Ritter Battery

The Slider