Thread: Dreamcolor flicker issue in low blacks when Hardware Engine is active

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  1. #1 Dreamcolor flicker issue in low blacks when Hardware Engine is active 
    When running out of the rocket and into AJA hi53g into a Dreamcolor monitor I'm experiencing flicker in the very low blacks. It's not noticeable on well lit scenes, however in low lit scenes it can be very distracting. I've also hooked the dreamcolor to a MXO2 and when using the calibration tool only a a very specific black level do I see flicker. 1 tick higher no flicker, 1 tick lower no flicker. I've recalibrated the monitor and still see the problem. I only see this when the Hardware Engine is active (ie: sending an RGB progressive signal to the dreamcolor.) If I send a YUV signal and the Hardware Engine is disable I do not see the problem.

    Wondering if anyone has experienced anything like this?

    Thanks,

    Joe
    Joe Kocsis
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    Developer of 'Crew Time Card' and 'Department Time Card' iPhone Apps
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  2. #2  
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    What's the monitor's refresh rate? Does changing it affect the problem?

    I've seen many, many 24fps projects show an apparent "flicker" with certain kinds of material, on DLP projectors, on CRT monitors, on plasma, you name it. I've never had a client complain about it, but I do check the scopes to make sure this isn't actually a lighting problem or a shutter-related issue. This can be really exaggerated with certain shutter angles as well, and is also an issue with 1080i material.

    BTW, thank you for CrewTimecard! Great app--this is one of several I've recommended to crew friends in the past.
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  3. #3  
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    Have seen exactly the same thing on my Dreamcolor. Never found a solution.
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  4. #4  
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    Quote Originally Posted by Joe Kocsis View Post
    a very specific black level do I see flicker. 1 tick higher no flicker, 1 tick lower no flicker.
    Wondering if anyone has experienced anything like this?
    Joe; what is the value that triggers the flicker? i have two Dreamcolor's one screen is new, and one is approaching 4 years old (it was one of the first out the door), and i work in RGB at least 80% of the time.

    I'm feediing them from one of these depending upon the job at hand;
    1) when in HD/RGB/444/DualLink -> BMD HDlinkPro-> DisplayPort
    2) when in HD/YUV/422/Single Link -> Aja -> HDMI
    3) When in DCi2K -> Nvidia4800 -> DisplayPort

    between two systems, two screens and three methods of feeding the screens and four years, i cannot remember seeing this... but would love to try to replacate the issue.

    Might it be specfic to RGB + HDMI input (one thing that I don't use)?

    d
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  5. #5  
    I've noticed this too, it's a quirk of the panel.
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  6. #6  
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    I noticed the same thing with the Dreamcolor conected to an mxo2 mini with Avid MC6 at 1080/23.976p 1080/24.00 1080/25p 1080/29.97p
    When I set the Output to 720/59.94p (in a 1080/23.976p project) the flicker was gone.

    According to this PDF

    http://bizsupport1.austin.hp.com/bc/.../c01695201.pdf

    the Panel doubles the frame rate of any signal under 47.952 Hz. Maybe that's causing the flicker.

    I also had the Dreamcolor conneted the HDMI of the graphics card at 1920x1080 60Hz and could not reproduce the flicker at low luminance levels.
    Florian Stronski
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