Film-Tech Forum ARCHIVE: Video image jumping

This is topic Video image jumping in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard May (Member # 2627) on 06-21-2014, 10:34 AM:

We run a lot of festival that are Blu ray and DVD. One issue that I have seen and not been able to figure out is the following. The projector is an EIKI X-85. Blu ray player is an OPPO BDP 93. When going from a dark scene to a very bright seen or from a scene to a still shot of something, the image goes crazy for anywhere from a quick blip to 5 or 6 seconds. Picture an old TV with the vertical hold screwed up. The picture rolls but in this case it rolls super fast and kind of at an angle, if that makes sense.

If you play the scene again, it may or may not do it. When it does do it again, it may be longer or short.

It happens on all the OPPO decks here with different Blu rays. It happens with maybe 1 out of 10 disks. The closest thing online I found was "Judder effect" which is a 24P thing. It's definitely not that.

Posted by Steve Guttag (Member # 268) on 06-21-2014, 11:28 AM:

Are you running component output, by any chance? If so, I have an answer for you.

Posted by Richard May (Member # 2627) on 06-21-2014, 03:52 PM:

Yes. Component.

Posted by Steve Guttag (Member # 268) on 06-21-2014, 05:05 PM:

There in lies your problem. If you look at the luminance signal on the "Y" (green terminal) with an O'Scope, you will likely see the sync pulse is modulating. I don't know why but some DVD and BluRay players will output, what best can be described as, a differential output. When the signal drops to near zero IRE...so does the sync pulse and the display effectively looses sync. The higher the frequency, the more dramatic the effect. For instance, if you drop your signal output to say 480i, odds are the problem will greatly diminish...but the higher you go, the greater the likelihood of the problem.

Now that most people are running nothing but digital signals, this normally isn't an issue anymore...especially since the "analog sunset" has taken place on the BluRay manufacturers.

The short answer is...move away from component output. If you have to use component, use a conditioner that will make the signal viable for your projector. Note too, if you try your S-Video or Composite output, you won't see the problem either. Not only are they 480i...they always have an "unbalanced" output.

Posted by Richard May (Member # 2627) on 06-21-2014, 05:19 PM:

Thanks Steve. The only reason we are using component is because we can't find an HDMI switcher that is compatible with the EIKI. All HDMI switchers so far make the entire screen purple. You can see everything in the scene but it is all purple. EIKI doesn't understand why.

Posted by Steve Guttag (Member # 268) on 06-22-2014, 06:26 AM:

Generally, when you have a color issue it is that you are not in the color space that the projector is expecting. Most HDMI devices are going to want to default to YCrCb but most can be set to RGB.

What I would do is not have any device set to "Auto" and force it to the color space that works for you. Oddly enough, RGB is generally the one that works for everything since if you have computers, that is the color space they will WANT to be and since the others can be set to RGB...it becomes the least common denominator. Use your Oppo as your test...bring it in via HDMI and switch its output between YCrCb and RGB and see what the Eiki does with each. Then put that behind your HDMI switcher (note...cheaping out on the HDMI switcher could also be your issue). Better ones can force EDID (the table that defines what resolution/colorspace...even audio). That can be used to get all devices to play on the same page and avoid these problems.

But I would get away from analog component video as fast as I could. Even when it was top-dog it was always problematic for reasons like you are experiencing. Things were just too close to the limits. Back in the SD days...I backed most of my systems down to S-Video despite HATING the mini-din connector because the problems disappeared and the video quality was essentially identical from a customer's point of view. We even had Extron work on their scaler design (DVS304) to try and make it more robust on that goofy differential component video output thing.Some players have it, some don't.

But in 2014...HDMI is where you want to be and you want to be VERY careful with HDMI too to ensure that nothing contaminates the signal in picture or sound because that EDID thing will definitely cause issues as will HDCP keys.