View Full Version : Levels/Gamma Shift?
05-12-2008, 02:40 PM
Forgive me if this has already been discussed. We developed a successful workflow using FCP with Proxies thru a Kona 3 card. However, we're experiencing an interesting issue. From time to time there will be a levels or gamma shift between play and pause. This is happening on both the computer and the client monitors. It seems to fix itself by playing with the AJA control panel and making sure it is set to Rec 709 for the ColorSpace and Gamma. But the issue will pop up randomly from time to time (when nothing has been changed). Has anyone experienced this?
05-12-2008, 03:45 PM
I ran into a similar situation using the proxies in After Effects. Changing bit depths back and forth on the project seemed to temporarily fix the situation.
I'd make sure to be running the latest version of Quicktime, if you aren't already.
05-12-2008, 03:55 PM
John, I noticed this happens too with same setup as yours. I'm looking into it.
05-12-2008, 05:17 PM
When I use the proxies in After Effects, I seem to get 2/3rds of the frame with a slight Gamma shift. The location of the 2/3rds never changes....
05-12-2008, 07:45 PM
The problem closely resembles the issue that Avids have with setting the proper Overlay mode on the video card (except it also affects the client monitors). So it could possibly be Quicktime/VideoCard/Kona card.
Anyone out there successfully running the Kona 3 setup without this random issue?
thanks for the info,
05-14-2008, 02:42 AM
I have seen this as well...
05-16-2008, 06:50 PM
When I use the proxies in After Effects, I seem to get 2/3rds of the frame with a slight Gamma shift.
What version of AE? According to a codec vendor I talked to, this was a known defect in both AE and Premiere. He thought it was fixed in AE, but I encountered it in Premiere and it made the app totally unusable. Here's a screen shot of the problem:
This only happens with greater-than-8-bit codecs, I believe, or possibly only RGB codecs. If this looks like your problem, you might get in touch with Adobe and refer to bug AE8-BG-01560 for AE and PP3-BGW-00628 for Premiere.
As far as the gamma shift in FCP between playing and paused, I've seen this in the FCP viewers. There is clearly different logic used between these two states: If you play a clip that has a black alpha channel, it'll be invisible; but if you stop it, it's visible.
05-17-2008, 08:10 PM
I can confirm that the issue is present with the most current version of Quicktime - 7.4.5. The troubleshooting continues.