Understanding RMD (backstage)

[fred gasc]

Hi,
I'm trying to understand how works and is implemented
The RMD in Red system.

If you are interested in this thread, what would be nice is
If we could end getting the correct nomenclature,
Demystify falses ideas etc...in short, get it right once for awhile.

My questions are:

-1) when I create a "mood" look using RCX, and save the RMD
Under the name of "look1".
This look1 can be loaded in camera or in software.
Can we consider this as a LUT? Is this a correct use of lenguage?

-2) it's been said in this forum over and over again that we can't
Grade Raw.
So I assume that RMD carries 2 types of informations. For
One part, raw metadatas like WB, ISO, color temp...BUT
When I'm actually using let's say color wheels,what really is happening
Behind the stage? because that's a color decision init?
So the RMD, as I understand them, are carrying more than
Raw metadatas but also informations that have to do with
Color correction? That point is still very vague to me.

-3) As I could verify over and over again with Red as well as with
Arri, maths (in color science) are the same regardless of the software. Wich fortunatly
Ensurre consistent and predictible results.
In that spirit, RMDs are universal with any Red material generation no?
I mean, whatever software I use, the "look1" rmd will give the
Same result for everybody regardless if it was generated in
Older RCX versions, and regardless if I load them in Sratch,
resolve, Nuke or any app that is capable to display the source
Settings (like alsp Avid or Lightworks). Is that correct?

 

[David Battistella]

1. It is a RED LOOK file. Technically it is a not a LUT but sort of a type of LUT that RED uses because it is a representation of the RAW data. RED camera's do now accept LUT's but the RED LOOK file is specific to RED. You can not use a RED LOOK file on other cameras, but you can use LUTS on other cameras and monitors.

2. Loot at it this way. The R3D file is a bucket or container that holds all of the data. The RMD file is a set of instructions of how that data is displayed as RGB. The container never changes, but how you extract the data from the container can. So as red changes a color space and you apply it to a 3 year old r3d, the R3D never changes but the instructions of how to extract and display the data does. The RGB is always being generated from the RAW data in the container. The RMD file is a very small file, where as the data reamins constant and the DATA CONTAINER.

3. Yes, provided all of the 3rd party software you are talking about are using the latest RED SDK and you are generating these looks based on the newer versions of the color science. It's best to stay with the newest versions of the color science.

 

[fred gasc]

Thanks David

"The RMD file is a set of instructions of how that data is displayed as RGB. "

I like this explaination because it becomes cristal clear to me.


So,

R3D never changes and as being raw, it contains let's say
A range of possibilities that are written in the RMD once we
Take a decision.

So in fact, RMD has nothing to do with raw values in themselves
As such, but is a "recording" of how to interprets or "transcode"
(again my nomenclature here is not very clear, if "transcode" being
A correct word) the original raw information into a RGB display
According to the operations a user has performed in RCX or other
Software capable of writting RMD.

So, using a paralel with cooking, R3D is the food in itself while
RMD is the receipy of how this food has been cooked?

But what I don't understand is why necesarly staying always with
The latest color science?
As an example, if I read the rmd in Resolve, and Resolve ain't Red,
How do I know Resolve is interpretating the datas according to
The latest color science?

In what sense the latest color science is important?


And that also leads me to a more oscur question:
We know that most important softwares are able to read
Natively R3Ds, RMDs and even some can write RMD as RCX
Does. So in the end, is RCX in 2015 still usefull?
Because being one more step.

 

[David Battistella]

Generally Resolve is the very best at using Red Software Developers Kit (SDK) to ensure that the latest color science is available within the software. You can use any color sciece you want to interprets RED's RAW data container to convert it to RGB (an image you can view).

In terms of the color science. The newer versions are generally doing a better job with color accuracy and various other things that come into play.

I still like RCX as a onelight creator and a way to review the footage.

IE. I might.

Capture.
View and set looks in RCX
Import into FCP X for proxy render
EDIT
then open in resolve
Throw out all the color and start again.

 

[Phil Holland]

And that also leads me to a more oscur question:
We know that most important softwares are able to read
Natively R3Ds, RMDs and even some can write RMD as RCX
Does. So in the end, is RCX in 2015 still usefull?
Because being one more step.

REDCINE-X Pro has certain features and a general ease of use for many tasks that something like Resolve, Speedgrade, or Baselight don't exactly provide. Or more acurately, don't provide without a great deal of other features that are sometimes not necessary.

There are many types of workflows out there in the world. Still to this day many folks produce a "one light" color correction in RCX and either create Quicktime or DNxHD Proxies for editorial use and/or export various formats for post production or VFX use. Generating a sequence of DPX images is a good example of that. Also, there are some who explore more of the subtle things that can effect image quality, like the various scaling algorithms which can be found in RCX that aren't exactly available in other applications.

As for the latest Color Science. Knowing if you are on the "latest and greatest" often comes down to the version within the Color Space name itself. DRAGONcolor, DRAGONcolor2, REDcolor, REDcolor2, REDcolor3, REDcolor4, etc.... If the 3rd party application uses an up to date RED SDK they have access to all of the recent Color Science developments and the users themselves have the ability to often change these settings within the software package. I usually work with DRAGONcolor or DRAGONcolor2 for instance, however, I know people who prefer REDcolor3 as a starting point.

Color Science and the freedom to change the Color Space without having it baked into the file itself is perhaps the biggest advantage of shooting with REDCODE RAW. Having White Balance freedom and ISO freedom (though most should try to shoot precisely) are additional benefits.

 

[fred gasc]

I quite like RCX because it's light and also because I cut in Lightworks...(I know we're maybe 10 editors in the world, hard core die hard users...but we're different and more glamourous!) And I always have RCX open at the same time as LW that I use as a commodity because LW is connected to the RMDs. So RCX acts as a source setting access within the editor.
That way, instead of having the traditional and ultra limited source setting access of Avid or PP, I got the
Entire RCX capabilities "within" the NLE in "real" time.
So for me, RCX has a meaning, no doubt.
As cutting native requires power and RCX is light, I've
Never noticed that RCX was slowing down the editing.
This technique is really cool in the sense that if a serious CC is not required, with masks and tracking etc...it's not even necesarly to roundtripp Resolve.
LW displays HD10bits but keeps intact native resolution in the background. If you zoom a R3D, it uses the native values, no worries. So RCX becomes a full color app in the NLE, and that's not yet possible to do so with Arriraw.
So to cut, I dowgrade the lightwork's debayer to 1/8 and put backs to full res or premium before DPX export.
Could not be more simple.

Ps: to be fair, Avid has a very powerfull technique concerning RMDs wich consists in using the "custom sift" option in the bins so if your project is well organised, with metadatas, you can assign looks in batch from the RMDs generated in RCX without touching the timeline. Lightworks can not do that
And needs RCX while Avid just needs the RMD but it's better and more straightforward in reframing because there's no strange oscur menu. If your material is 4k it's for k, if it's 50k it's 50k, even if the display is hd. When export, resolution is there again,
Intact.

So yeah...rcx is cool.