Barco Graphics 808 and HDTV (1 Viewer)

[Johnny.McN]

I've got a Barco Graphics 808, and I'm trying to get it working with my cable company's HD cable box.

I've got an Audio Authority 9A65 transcoder to get from the component output on the cable box, to the RGBHV input on the Barco.

All non-HD channels work perfectly fine. My progressive scan DVD player works fine too.

I'm not getting any results for the HD channels. Well, the Barco tries to adjust to the signal, but I get a very distorted screen for a second or two, and then the Barco tell me "no signal". The best way I can describe it is like when you try to view a premium channel when you're not a subscriber - sort of like it's scrambled.

When I switch to the HD channels, the transcoder tells me that the signal is 1080i.

Does the Barco Graphics 808 work for HD? Or does it look like the cable company doesn't have the HD channels turned on or unscrambled?

 

[Sami Kallio]

I don't think it can handle 1080i, only 720p. 1280 x 1024 seems to be its max resolution which is perfect for 720p (1280x720) but quite a lot short from 1080i (1920x1080). Distorted screen I think is a result of you feeding it higher resolution it can display.

 

[Johnny.McN]

Hmm... The specs for it say 1600 x 1200, and HDTV capable...

 

[Sami Kallio]

Even then that's still less than 1080i. Do you have any means to downscale it to 720p?

 

[ChrisWiggles]

sami is incorrect, the G808 should be able to handle 1080i just fine(at normal refresh rates). It scans out to 110 khz, which 1080p even is well within range of.

Are you running your DVD player and your HD box through the same transcoder?

One thing that you need to be aware of is that on port5 (the BNC RGBhv input) the Barco needs negative sync. It will take neg or positive on port 3 with an adapter. This may be the cause of the sync problem. Does your transcoder have an option for this perhaps?

Sami: 1600x1200, presumably progressive 60hz, is more than twice what is required for 1080i 60hz.

 

[ChrisWiggles]

this also isn't really a basics question, display forum will probably be preferred.

 

[Sami Kallio]

Yes, I forgot that CRT "downscales" automatically to its max. resolution. So it should be able to display 1080i, just not at 1080i resolution?

 

[ChrisWiggles]

No, this CRT has no onboard scaling, what you feed it is what you see. If you feed it 1080i, you'll see 1080i. It's a professional display, it doesn't have any on-board scaling, and it's a true multi-scan monitor, so it will basically sync to any oddball resolution you could possibly want. It is not like many consumer CRT tvs that only accept and display limited resolutions and provide some scaling, nor is it like digital displays that scale to their native panel resolution.

So what I'm saying is that if you feed this machine 1080i 60hz, that's EXACTLY what you'll see if it syncs to it (which as I explained it should). It won't downscale or upscale as there is no internal scaling. I believe Runco has sold these with built-in scaling at some point, but I don't believe the OEM Barco units were ever offered with internal scaling, but in any case it would be an add-on.

 

[Sami Kallio]

I know it doesn't need to scale but if the resolution fed is higher than it can display then I don't see how it is exactly what you feed it. If the maximum resolution is 1600x1200 then that's what you get. It's not downscaled in the sense that in digital projectors but still it is. The tubes throw a picture as good as they can which translates to 1600x1200 according to specs (I was looking at wrong model earlier).

 

[ChrisWiggles]

That's a different question, this machine won't "resolve" full out to 1600x1200, but my point is that 1080i is displayed as 1080i with no scaling at all, and it WELL within the spec'd range of the G808. The resolving power question is a much more complex one, and changes from machine to machine depending on setup. The problem reported here is a lack of sync, not a resolving issue, because there is no picture being seen, so resolving power isn't even really coming into play because there isn't anything being resolved at all!

 

[Sami Kallio]

Yes, I know, the above was already OT. Distorted picture (I don't know if it's the same kind as in Johnny's case) is a symptom of too high frequency in my CRT.

 

[ChrisWiggles]

Which indicates to me that there is something at fault in the source sync generation, because as I said 1080i is well within the capabilities of a G808. I have a G808 myself among my displays, and it should have no problem at all with 1080i at standard video refresh rates.

 

[Johnny.McN]

Thanks very much Chris and Sami for the replies.

I'm sorry if this isn't in the right forum, but I'm not an expert with any of this, so I thought I'd start in the "Basics"...

Chris, from what I gather you're getting at, it seems like a sync problem? (Please bear in mind, I don't exactly know what sync is...)

I'm feeding the both the progressive-scan DVD and the cable HD box through the transcoder and then to the RGBHV (source 4).

The Audio Authority transcoder has one switch for the type of sync, either RGsB (3 connectors, sync in green) or RGBS (4 connectors, separate composite sync). I have it set to RGsB, using three connectors. On the panel or RCU, I select source 4.

This works fine when I plug the DVD component output into the transcoder, but not when I plug in the HD cable box component output.

For now, I'm just switching the physical cables going into the transcoder, not changing anything with the connection between the transcoder and the Barco. Eventually, I'll have a switch, so I won't have to physically change any cables.

The one thing that concerns me is that the one example in the Barco installation manual that has an HD source, connects to the RGBHV (source 4/5) using something called tri-level sync, which requires an optional board in the Barco. It doesn't say that's the only way to connect HD, but I don't see anything to the contrary either... Have you ever gotten HD to work on yours without the tri-level sync?

Thanks for all your help.

Johnny

 

[ChrisWiggles]

yeah, I just run RGBhv to port 5, I'm runnin 720p 72hz at the moment, but I've used 960p 72hz before. I haven't pushed 1080p to it, and getting 1080i out of a computer is a little bit copmlicated, but 960p 72hz is *well* beyond the requirement for 1080i, so you shouldn't have any problem with HD on your G808. What I mean by a sync problem is that if the sync signal is not negative polarity (which is what the barco likes on port5) then you'll get a scrolling picture usually, or it will lose sync and say "no signal." Also, if there is something wrong with the source's generation of the sync signal it can cause problems. It certainly is possible that there is something amiss with your G808, but I doubt it.

you have a private messate as well.