FCP Color and Gamma Handling on 4:4:4 RGB Media
by Tobias Heilmann
on
Aug 21, 2008 at 7:07:24 am
Hi Everybody.
We shot RAW footage (RED). Converted (First Light CC) to 10 Bit DPX. Converted to AJA 10 Bit 4:4:4 RGB Codec. Went to Color to grade (10 Bit Mode). Exported in the same AJA Codec, imported to FCP (6.0.3), the timeline matches the codec settings. Clips playback fine (look great), the image is identical to that in Color. As soon as I render anything with those clips (crop, filter, size, etc. doesn't matter what) I see a dramatic shift in what I perceive to be a darker Gamma Level. I see this both in the Viewer, as well as the Kona3 Dual Link Output.
The render settings of the time line are RGB.
Can someone explain what might be happening here? How does FCP really handle RGB footage? FCP is YUV native, is that correct?
I could just readjust the gamma an be (visually) happy. But this defeats the purpose, doesn't it? Constantly jerking a picture back an forth.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Rafael Amador on Aug 21, 2008 at 9:18:15 am
Hi Tobias,
Is the setting of your sequence codec Full range?
[Tobias Heilmann]"FCP is YUV native, is that correct? " No really. FC is a Video Editing application and video is YUV.
But FC works perfect in RGB. In fact until three or four years ago all the FC effects and transitions rendered in RGB.
When you change from one color system to the other is normal that happens some shifts in colors and gamma,but when you fallow all the process in one or the other this shouldn't happens.
rafael
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Tobias Heilmann on Aug 21, 2008 at 9:34:39 am
We used the full range, as we wanted to keep the field open until the time we needed to narrow it down.
Of course I am not sure whether Color exports the exact same way, as I ony choose the codec.
These papers discuss how FCP handles 10-bit material and may point you in the right direction. The basic gist of the second paper is that very few FCP effects are 10-bit enabled and FCP never tells you when it takes 10-bit material down to 8-bit on effect that are not capable of 10-bit rendering.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Tobias Heilmann on Aug 21, 2008 at 2:56:49 pm
Thank you.
I have not read those two papers yet... but it goes straight to my question: How do I know what FCP is doing to my footage?
We even tried just re-exporting the AJA 10 Bit RGB 4:4:4 clip from the timeline without doing anything to it at all. We then compared the exported clip to the clip that Color generated. The FCP clip is darker.
We compared the two clips by viewing them via AJA TV, our Kona3 via Dual Link Out.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Tobias Heilmann on Aug 21, 2008 at 2:57:23 pm
Thank you.
I have not read those two papers yet... but it goes straight to my question: How do I know what FCP is doing to my footage?
We even tried just re-exporting the AJA 10 Bit RGB 4:4:4 clip from the timeline without doing anything to it at all. We then compared the exported clip to the clip that Color generated. The FCP clip is darker.
We compared the two clips by viewing them via AJA TV, our Kona3 via Dual Link Out.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Tobias Heilmann on Aug 21, 2008 at 3:15:48 pm
...ok I just read those links. Thank you! Very interesting.
Can't say that the question marks have vanished. These papers explain a problem, which is yet of a totally different scope.
From reading those papers I still can not discover, why FCP would change the look of my footage just by placing it in a timeline (identical to the footage) and then exproting it from there.... Hmmm.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Rafael Amador on Aug 21, 2008 at 4:13:41 pm
Well, is clear. The only thing you can do with 10RGB footagein FC without spoil it, is to cut and export without re-compression.
In the moment that you render, your 10b RGB become a 8b RGB. So instead of having 1024x1024x1024 colors, you have 254x254x254.
The only better solution than the one pointed in the articles, is to use Sheer !0b YCbCr 444.
You would keep the most of the color information from the 10b RGB 444.
rafael
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Charles Taylor on Aug 26, 2008 at 7:06:05 pm
Just posted a show in 1920x1080 AJA 10bit RGB. Had no issues...
Our workflow was:
Edit DV offline.
Re-link FCP media to 10bit RGB files (changing sequence settings, obviously)
Export specific shots for VFX.
Render TIFFs out of Shake.
Use AE to make 10bit RGB QT out of TIFFs (10 bit QT is broken in Shake right now).
Replace VFX on timeline with the new QTs.
Used FCP "Send to Color".
Graded in Color, monitoring with KONA 3 on Christie Roadster.
Rendered.
Used Color's "Send to FCP".
Rendered out at 1080 and 720 with Compressor to Apple Uncompressed and DVCPro HD (our delivery format).
Observed no gamma shifts (thank god...).
Maybe if you could post your exact workflow like that, we could narrow it down?
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Tobias Heilmann on Aug 26, 2008 at 8:09:41 pm
Hi,
As posted initially, our worklflow looks as follows:
RAW footage (RED)
Converted (First Light CC) to 10 Bit DPX in Red Cine (The AJA 10B 4:4:4 Codec is not available in Red Cine at this point,
Used AJA DPX Converter 5.1 to convert 10B DPX Files to 10B 4:4:4 RGB Codec.
Imported on to 10B 4:4:4 Codec Timeline (FCP 6.0.3). (Render RGB Settings)
Sent to Color (1.0.2) to grade (10 Bit Mode)
Sent back to FCP in the same AJA Codec.
Sequence still same settings.
Clips playback fine (look great), the image is identical to that in Color. As soon as I render anything with those clips (crop, filter, size, etc. doesn't matter what) I see a dramatic shift in what I perceive to be a darker Gamma Level. I see this both in the Viewer, as well as the Kona3 Dual Link Output.
Even when I just export this sequence as a Quicktime Movie (using original settings) without rendering anything, I get this shift in the exported movie.
Re: FCP Color and Gamma Handling on 4:4:4 RGB Media by Charles Taylor on Aug 26, 2008 at 8:45:16 pm
I would wager you're running up against any one of several things.
1. For some reason, the Render in RGB setting. I left this alone when I was working in 10 bit RGB.
2. The preference regarding gamma levels for RGB settings. There are a variety of options there, I suggest trying them and seeing what happens.
3. Some ColorSync nonsense (I know, it shouldn't be relevant, but you never know). What gamma is you monitor set to? FCP expects gamma 1.8.
If I may ask, why are you using the 4:4:4 codec? Since FCP will convert your 10 bit to 8 bit anyway, I might try using a YUV(ish) codec. Or do an offline/online workflow using DPX. (Sorry, I'm sure you've considered this and rejected it for some reason, but just thought I'd bring it up).
If you want, you could try sending me a few frames of your original footage, and I'll try your workflow myself (I don't have dual link, but otherwise my setup is similar).
