garageCube

[Lumenarius]

Logging in to finally see about finding a solution to a recent issue out at a live event.

Before sharing every file and detail possible I wanted to share a high level description of the issue and see if that made any sense.

This was for a project with x3 computers running x6 projectors each.

Each machine was the same 2022 MBP M2 Max running Resolume Avenue into MadMapper with a 8196x780 content, Apple ProRes 422 HQ Codec, .MOV container, and at 30 FPS.

It was a mix of video footage as well as CGI scenes from Blender and After Effects.

The video out was sent into DataPath Fx4 units running HDMI into BlackMagic 12G SDI converters that were routed over fiber, then back to SDI, into the Panasonic RZ-21k projectors.

The problem was that during playback the video would appear to glitch or drop out. I was not able to catch this on camera but it was as if the data would get corrupted and was causing the projectors to spaz out.

I tried everything I could think of (on site, night before the show mind you). New content, re-render from scratch, different codec, different frame rate, new adapters, etc.

The only thing that helped was to turn the opacity on the clip to 90%.

This worked if I did so in either Resolume on a per clip basis. It also worked if I turned down the master output on MadMapper.

This happened on every computer and would be present in the same clip across each computer at similar but hard to determine moments. I.e. usually at 30 seconds but not exact to the frame.

Each time it would glitch the effect and pattern would be different though similar. Usually a mix of the projector going blank or showing corrupted data and weird colors.

My hunch is that for some reason the video file had pixels that would be over 255,255,255 in some areas and were causing the video distribution to mess up.

However, that is only a hunch. It was my first 8K gig and also the first time I have ever seen this issue.

With all of this in mind is there a good reason why this might happen?

Anything I can test out to try and see if I can replicate it?

Unfortunately I do not have access to all of the gear or we would set it up again and try it ourselves.

Thank you in advance!

[mad-matt]

That's very strange. You should first see at which level the issue is happenning: at resolume level, at spout level (in MadMapper medi preview), in MadMapper output preview, in the 4k output of one of the computer, at the output of the Datapath FX4, at the output of the BlackMagic 12G SDI. I suppose the issue happens at HDMI -> SDI conversion. I'm not an expert with SDI. If there's any BlackMagic device firmware update you should try that first.

[Lumenarius]

Hello Matt, thank you for chiming in!

I can say that there was no glitching in the MM or Avenue preview panes.

We did put a field monitor on and up until the SDI output and everything looked fine there too.

However, it always happened at the same time in the visual (+/- a few frames). Some visuals did not do this, like stock videos.

We of course did try to update the firmware on everything but nothing changed.

Once again the only thing that solved this (figured it out the night before the show) was to turn down the master output to 90%.

Nothing else worked.

This leads me to believe it was a "clipping" issue with the files or the RGB data.

Further, it only glitched when there were bright sections in the video. If it was dim or dark, no issue. But if there were large section of fully bright 255,255,255 pixels that is when the issue would arise.

[mad-matt]

MadMapper output to the graphics card is a RGBA 32 bits buffer (8 bits per component). There can be clipping to full white (ie using a white image and increasing brightness), but it's just like displaying a white image in the output. There's no more data stored. So if the issue only happens when you have large white sections in the image, you should be able to reproduce it with a simple full white image or an image that has some full white portion. This could still be an issue at HDMI=>SDI conversion. I see no way it could be MadMapper related. I suppose displaying the same video with any movie player in the same configuration would lead to the same issue on the SDI output.

[Lumenarius]

Mad-matt, I think you are correct in that the issue is potentially in the SDI conversion rather than MM; especially as you can confirm that MM will clip the values to 255 even if brighter.

I recall an issue with the Arduino whee if an integer would be over 255 (like 345) and put into an LED it would turn weird colors so I was curious if it was maybe something *like* that.

I will be sure to document better in the future the exact setup and to film the glitch effects.

Thank you