Equipment Failure in Multi - Projector SDI Setup

[Wasko]

Hey all, 

I recently had what I’d describe as a ‘technological crisis’ at an event. We pulled through by only by the skin of our teeth. The problem we had is complex, with many levels that I don’t fully understand. I’m seeing this as an opportunity to broaden my knowledge and wanted to reach out here for voices of experience.



The event was a corporate gala, the plan was to output to 6 projectors rigged on Truss from Resolume / media server and two matrox triple heads connected Via DisplayPort for a very wide panoramic backdrop. 



The pipeline summarized: 



- Media server outputting 3840x720(3x 720p) to two triple heads via DisplayPort. 



- Tripleheads have 6 DP - HDMI adapters connecting them (via HDMI) to an assortment of HDMI to SDI converters. One had 3 Theatrix Xvisions, the other 3 kramers. 



- From there the signal is sent via a long SDI cable run to 6 projectors flown on truss. Each triple head outputs to 2x 1080p Barcos, and 1 XGA Christie respectively.



First issue is that the Xvision SDI converters would not take the triplehead’s signal whatsoever. They did not even recognize the HDMI cable being plugged in. I have looked through their documentation and they seem capable of receiving virtually any resolution and refresh rate, which is confusing to me. If this is an issue of refresh rate or an issue with the Triplehead, I want to know what hardware I should purchase to alleviate this (Datapath X4?) or at least the underlying issue so that I can avoid it in the future. 



Second issue is that while the Kramers did deliver the signal to the projects, the projectors were not scaling the image properly. By this I mean that the projectors were showing half-raster; particularly noticeable on the 1080 Barcos. I can imagine that this is because I am outputting 720p to 1080p projectors via triplehead, but I seem to recall projectors in comparable setups scaling properly regardless of the triplehead.

We ended up bringing another server with 5 on board outputs so that we could avoid tripleheads altogether. We then ran into the strange problem of the Barco projectors not receiving signal from the Theatrix Xvisions, only the kramers. Because of limited back up SDI converters, this complicated the setup massively. Looking through the documentation of the Xvision, it is beyond my why they were unable to carry the signal. I am thinking it has something to do with the refresh rate of my computer’s outputs, but I am unsure. The XGA Christie 10ks took signal from anything we threw at them, only the Barcos had this problem. 



I have a suspicion my solution here might be a Datapath x4 for future events.

This is a lot to read, but I am hoping one of the video superpowers of this forum (Oaktown?) might be able to shine some light on underlying issues. I’d like to take this as an opportunity to broaden my knowledge of the equipment so that I can go into similar situations with more foresight. 

Here’s a rough diagram of the pipeline that failed. 



https://imgur.com/a/l1ABy

Thanks!

[drazkers]

Hey all, 

I recently had what I’d describe as a ‘technological crisis’ at an event. We pulled through by only by the skin of our teeth. The problem we had is complex, with many levels that I don’t fully understand. I’m seeing this as an opportunity to broaden my knowledge and wanted to reach out here for voices of experience.



The event was a corporate gala, the plan was to output to 6 projectors rigged on Truss from Resolume / media server and two matrox triple heads connected Via DisplayPort for a very wide panoramic backdrop. 



The pipeline summarized: 



- Media server outputting 3840x720(3x 720p) to two triple heads via DisplayPort. 



- Tripleheads have 6 DP - HDMI adapters connecting them (via HDMI) to an assortment of HDMI to SDI converters. One had 3 Theatrix Xvisions, the other 3 kramers. 



- From there the signal is sent via a long SDI cable run to 6 projectors flown on truss. Each triple head outputs to 2x 1080p Barcos, and 1 XGA Christie respectively.



First issue is that the Xvision SDI converters would not take the triplehead’s signal whatsoever. They did not even recognize the HDMI cable being plugged in. I have looked through their documentation and they seem capable of receiving virtually any resolution and refresh rate, which is confusing to me. If this is an issue of refresh rate or an issue with the Triplehead, I want to know what hardware I should purchase to alleviate this (Datapath X4?) or at least the underlying issue so that I can avoid it in the future. 



Second issue is that while the Kramers did deliver the signal to the projects, the projectors were not scaling the image properly. By this I mean that the projectors were showing half-raster; particularly noticeable on the 1080 Barcos. I can imagine that this is because I am outputting 720p to 1080p projectors via triplehead, but I seem to recall projectors in comparable setups scaling properly regardless of the triplehead.

We ended up bringing another server with 5 on board outputs so that we could avoid tripleheads altogether. We then ran into the strange problem of the Barco projectors not receiving signal from the Theatrix Xvisions, only the kramers. Because of limited back up SDI converters, this complicated the setup massively. Looking through the documentation of the Xvision, it is beyond my why they were unable to carry the signal. I am thinking it has something to do with the refresh rate of my computer’s outputs, but I am unsure. The XGA Christie 10ks took signal from anything we threw at them, only the Barcos had this problem. 



I have a suspicion my solution here might be a Datapath x4 for future events.

This is a lot to read, but I am hoping one of the video superpowers of this forum (Oaktown?) might be able to shine some light on underlying issues. I’d like to take this as an opportunity to broaden my knowledge of the equipment so that I can go into similar situations with more foresight. 

Here’s a rough diagram of the pipeline that failed. 



https://imgur.com/a/l1ABy

Thanks!

1#SDI only handles YUV as a colour space. The xvision is a plug and play device and i wouldn't be surprised if they send an edid asking for that YUV colour instead of converting from rgb on the device. Which would explain why they wouldn't work with the triplehead. Soon as you got past the triplehead to the media server, then you would of been able to send YUV.

2#Also i've toured with abunch of Barco 20-30k projectors and using the barco projector toolkit you can zoom the sampled area, similar to Resolume's input slices. Your projector tech should of been familiar with this software and had known this. I've used this function to cover more space by sending 1920x1080 but zooming to view like 1920x1200.

3#Also people need to realize that there is SDI and 3G SDI. SDI has a max of 1080p@30, 3G SDI can do 1080p@60 The xvision does support 3G SDI but i bet the kramers models you had did not.

I'm assuming that after you moved past the tripleheads you went up to 1920x1080 from the media server. Partly because your projector tech didn't know about the barco projector toolkit.

The barco CLM HD8(I'm guessing) doesn't support 3G SDI, just SDI. So yes your frequency was the reason. If you swapped to 1920x1080i@59.94 or 1920x1080p@30 the barco would of likely picked it up. Most computers natively send out progressive so changing everything to 1920x1080 with a frequency of 30 is good for troubleshooting with SDI straight from a machine.

edit: I actually feel pretty confident about diagnosing these issues from my comments above. A lot of people will just say change your cables. But it reminds me about slowly learning about SDI and signal engineering early in my career. Usually i figured all these things out, 1 by 1, you got unlucky and ran into everything. I've moved into D3 for corporate events these days but your description really reminds me of starting out and working with AV companies that just started buying SDI gear.

[Wasko]

Thanks for your response, I still haven't unraveled the full issue but these are some great points to study up on. I've been digging into this world of YUV, RGB and scaling - there is always so much more to learn.

Your first point about not recognizing RGB via the Matrox Triplehead makes sense. I'm curious of if there is a piece of hardware or any possible workaround to make the Triplehead work. If this is just an incompatibility specifically with the Triplehead, would a Datapath be capable of outputting YUV colorspace? I know that 3G-SDI is a standard in the industry, so I am curious what combinations of equipment are used to make this reliable and possible.

I'm fairly certain the Barco we were using was the CLM HD8 (http://www.projectorcentral.com/Barco-CLM_HD8.htm) which as far as I can tell (read through the manual) does not have an on board zooming functionality. This is making me think that if I want to output to projectors with varying resolutions via triplehead I'll need a scaler like Decimator MD-HX. With my current budget it's more a matter on deciding on what is most valuable for the investment in new equipment (multiple Decimators, Datapath FX4, etc).

Our projectors, converters and (I assume) cabling were all 3G-SDI capable, oddly enough.

Why the Theatrixx Xvisions were not compatible with the the Barco's, but very much so with the Christies is still beyond me. Digging into it further and hoping to come to some sort of understanding.

[drazkers]

Thanks for your response, I still haven't unraveled the full issue but these are some great points to study up on. I've been digging into this world of YUV, RGB and scaling - there is always so much more to learn.

Your first point about not recognizing RGB via the Matrox Triplehead makes sense. I'm curious of if there is a piece of hardware or any possible workaround to make the Triplehead work. If this is just an incompatibility specifically with the Triplehead, would a Datapath be capable of outputting YUV colorspace? I know that 3G-SDI is a standard in the industry, so I am curious what combinations of equipment are used to make this reliable and possible.

I'm fairly certain the Barco we were using was the CLM HD8 (http://www.projectorcentral.com/Barco-CLM_HD8.htm) which as far as I can tell (read through the manual) does not have an on board zooming functionality. This is making me think that if I want to output to projectors with varying resolutions via triplehead I'll need a scaler like Decimator MD-HX. With my current budget it's more a matter on deciding on what is most valuable for the investment in new equipment (multiple Decimators, Datapath FX4, etc).

Our projectors, converters and (I assume) cabling were all 3G-SDI capable, oddly enough.

Why the Theatrixx Xvisions were not compatible with the the Barco's, but very much so with the Christies is still beyond me. Digging into it further and hoping to come to some sort of understanding.

Decimator would allow the triplehead. Best and more versatile kit then just a datapath for your work.

That projector does picture in picture so it 100% does image scaling.

Projector spec says sdi/hd-sdi. So it can’t handle 3G sdi. Its a critical difference even if a projector is a 1080p capable projector. If something mentions sdi twice it’s telling you the frequency.