Picture trembles vertically

[Alban Birch]

Hi we have trouble with our Series 1 Kinoton DCP30 (Barco) and Doremi DCP2000 with Intelboard. The image suddenly started shaking vertically. It is permanent, not intermittent. Its not so visible while a film is running, but very clearly in the end credits, these are barely readable. We tried the Testpatterns of the projector and alternative content through the DVI Inputs, everything just fine. We tried swapping the SDI-Cables and SDI-Inputs on the projector, but no improvement.
Did anyone have that issue or has an idea what it could be.
I'll try a different Doremi tomorrow.

[Mark Gulbrandsen]

The first two things I'd check are the blowers for induced vibration, and then the lens.

[Alban Birch]

Thanks Mark, but I don't think that it's a mechanical problem, because the testpatterns are rocksteady and alternative content through DVI are normal too.

[Mark Gulbrandsen]

Yep, then it's a problem some where in the signal chain...

[Alban Birch]

Been to the cinema myself and had a look at it with my own eyes. Technically everything is in order. It seems to be a framerate issue with a badly converted DCP.
Our CP2210 plays the content without problems, is the processing that better in the Christie compared to our Kinoton/Barco DCP30?

[Carsten Kurz]

What is the frame rate of this DCP? Series 1 is far more limited in frame rates than series 2.

[Marcel Birgelen]

If I remember correctly, the Kinoton DCP30 won't do 25 or 30 FPS @ 2K, it should do 25 FPS @ FullHD (1920 x 1080) though, although not officially supported.

[Marco Giustini]

If other content look ok, then it is definitely an issue with that content - or with framerate as suggested.

[Alban Birch]

The framerate is 24fps but the source was 23,97. Apparently it was converted frame by frame, so the DCP runs a bit shorter

[Marcel Birgelen]

If the content is in 24 fps, the framerate can't really be your problem. You indicated the content looks fine on your CP2210, so the problem must be something else. Was the content converted to M-JPEG2000 or to MPEG-2? And did you check the resolution of the DCP?

[Carsten Kurz]

Very strange. Yeah, maybe the container size is non-standard. HD-SDI does not support any arbitrary image parameters, and even if it did, the series 1 input signal processing does not support any format, nor does the Dolphin card output any arbitrary format.

It would be interesting to get a hand on this DCP. If too large, the metadatafiles would probably be enough.

- Carsten

[Randy Stankey]

The framerate is 24fps but the source was 23,97. Apparently it was converted frame by frame, so the DCP runs a bit shorter

Is there any chance that the source was interlaced?

If so, was the material properly de-interlaced when it was converted?

If interlaced video is shown on equipment that expects progressive, all sorts of weird things might happen, including vertical jitter and/or a Venetian Blind effect as the equipment tries to interpret the data stream.

[Marcel Birgelen]

If there is interlaced content inside the DCP, it theoretically should look awful on all DCI machines as no supplier I know supports in-line de-interlacing of DCP content, let alone would activate such a filter without prior activation.

A non-standard container size feels like it could be the culprit. Like Carsten indicated, the HD-SDI link will not do any resolution switching and if the image isn't properly formatted/resized before it hits the SDI link, it could result in all kinds of timing issues, with a very glitchy output as a result.

[Randy Stankey]

Okay... For some stupid reason, I read that the original material was 29.97 fps instead of 23.97. Dumbass mistake on my part.

But, assuming that... We all know how converting from 30 fps interlaced to 24 fps progressive can be a PITA and we can all imagine what kinds of hiccups could occur if such a conversion wasn't done properly or not done at all.

Since activating the de-interlace feature is often a matter of just ticking off a check box, it's easy to forget. I know that I have forgotten on many occasions and... DAMMIT! I have to go back and do it all over again!

That's where my thoughts were going when I posted that.

Yes, I also agree that an improperly formatted container can cause all kinds of Hell to break loose, too.

And...yup! I've done that, too!

There's probably no mistake you can make that I haven't done at least twice, before!

[Alban Birch]

Carsten had a look at the DCP, everything looks fine and as said, it pkays perfectly on a CP2210. Seems to be a Series1 problem