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Using XENA with LCD's

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David Mack
Using XENA with LCD's
on Jun 8, 2007 at 1:30:16 pm

Hi,

I'm considering moving over to a Xena system. Just wondering if anyone has used the AJA HDP HDSDI to DVI converter? I want to use an LCD monitor to view the video/animations (as I do currently with my BlackMagic card). Specifically, has anyone hooked one up to a Dell 27"? If so, when playing back 1080P, does it map pixel for pixel (ie you're left with a black bar at the top and bottom of the screen because monitors are 1920 X 1200) or does it stretch the image over the entire vertical resolution (1200)? Lastly what is the refresh rate at 1080P - does it use the monitor at 50Hz showing 25fps progressive or does it interlace (like the BM card)?

Any info greatly appreciated!


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Jeron Coolman
Re: Using XENA with LCD's
on Jun 8, 2007 at 4:04:25 pm

I have a Dell 24" that I've connected via component outs of the Xena LH and the Premiere Pro HD timeline looks horrible on it. It isn't a Xena thing, it is a Dell monitor thing, because all HD component signals look bad on it.

The LG 24" monitor that I've connected via component outs of the Xena LH looks great when displaying my HD timeline. I was amazed at how much better the LG looks when viewing an HD signal.

I've yet to see a good looking HD signal on the Dell 24" monitor. The image always looks like the Dell is doing a poor job of trying to "make it look better"; e.g. it looks like the sharpness is turned up too high and the colors don't look right.

I discussed this in another thread somewhere with another person who is trying to connect to his Dell with, I think, an HDMI -> DVI connector and he reported the same poor picture.

The Dell looks great when I connect the computer to the DVI and set the resolution to 1920x1200 though, so it gets the thumbs up as a computer monitor :)



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David Mack
Re: Using XENA with LCD's
on Jun 8, 2007 at 6:49:02 pm

Hi Jeron,

Oh! Not really what I wanted to hear but thanks!! Strange though. My current setup comprises a Black Magic Multibridge Extreme. It has a DVI output and that is connected to a 27" Dell monitor - the picture quality is awesome! Apart from the refresh rate (25Hz Interlaced) it is as good as an LCD being used by a computer - really, it is stunning! It would be a shame to finally get image sequences playing off the timeline only to find that the result looks rubbish!!!!

Has anyone tried attaching to an lcd via a AJA HDP HDSDI to DVI converter? Does that give good results?


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Jeron Coolman
Re: Using XENA with LCD's
on Jun 9, 2007 at 4:11:41 pm

David,

Check out this thread. It is the one where me and another person are discussing the problems we are having with an HD signal playing on a Dell 24".

http://forums.creativecow.net/readpost/162/864905?

I plan on getting an HD-SDI to DVI converter as well in an effort to not use an analog signal to monitor, so I'm interested in how well those work too.

Jeron


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David Mack
Re: Using XENA with LCD's
on Jun 11, 2007 at 6:57:17 am

Hi Jeron,

With the Black Magic system, coming from the Multibridge Extreme, you really are seeing an image quality that is identical to a standard computer monitor - there appears to be no degrdation in signal quality at all. When I got my system, I did an image sequence with invividual pixels, edge lines, subtle colour changes etc to really test it. I was pleased to see that it genuinely was a pixel for pixel mapping with no drop in quality. The only issue I have with the playback is that it refreshes the LCD at 25Hz interlaced. This means that you can (if you have quick eyes!) see the individual fields and so when you have horizontal movement, you see feathered edges. If the system could be made to work at 25FPS Progressive, with a screen refresh of 50Hz, then I think (maybe apart from colour ) you would have the ultimate monitoring solution.

What converter are you thinking of getting? The AJA?


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Jeron Coolman
Re: Using XENA with LCD's
on Jun 11, 2007 at 2:39:33 pm

David,

I had a funny feeling that the Blackmagic was supplying more of a "computer display" signal through the DVI than a "1080i" signal, because the Dells just don't seem to like the 1080i signals (from HD devices; camera, HD-DVD player, etc.) that I give them, but they love a "computer display" signal at 1920x1200.

I'm not sure if I'm going to need a converter with the LG monitor. I'm moving my studio and at the same time, finishing a new dual-quad core machine, with 4 terabytes of Areca raid storage for my Xena card. I bought the Dell, saw the poor picture, then bought the LG to use in order to monitor my timeline via component out of the Xena.

Yesterday, I finally did some testing with the LG and the component connections. I used to use an HD TV connected with the component connections of the Xena. The TV one of the lower HD resolutions than 1080i, so it would downscale the picture to the lower resolution.

I connected the Sony HDV deck to the HD Connect LE and connected it to the Xena via HD-SDI. I connected the component out of the Xena to the component in of the LG. I connected the component out of the HD Connect LE to the HD TV's component in.

I then captured some uncompressed HD via Machina and watched the same footage playing on the HDTV and LG side-by-side. The difference in quality was huge. The LG looked alot better, so I'm pretty sure it will be fine for my purposes.

I think I'll just keep the Dell as a 2nd computer monitor and if I decide I want a pure digital connection to the LG from the Xena, I'll get an HD-SDI to HDMI converter from Convergent Design for around $300.

Jeron



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David Mack
Re: Using XENA with LCD's
on Jun 11, 2007 at 4:38:32 pm

I think I'm going to give this a go, using either the HDP or BM's HD-Link. I'll let you know how I get on.

Thanks


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Tim Kolb
Re: AJA HDP
on Jun 13, 2007 at 1:56:04 pm

Hi guys,

Sorry...I'm on the road and not in here nearly as much as I'd like.

I have an AJA HDP SDI>DVI converter. It works quite well. I've used it with a Dell 24" LCD and the picture looks as good as that LCD can look. Like most AJA boxes, it's well-made and pretty much plug-in, turn-on, and go...

The Dell 24" needs to be fed a digital signal, the analog input doesn't work very well.

The DVI output is always a "computer-type" signal...there is no video equipment that uses DVI for monitoring. The BM DVI interface is there expressly to enable the user to use an inexpensive computer monitor instead of a pricey CRT or high-end CineTal, E-Cinema, or JVC LCD panel with HDSDI inputs.

Keep in mind that average LCDs are limiting as far as dependable color correction is concerned. I would get a good calibration program like cineSpace to optimize the representation of the image on the LCD.



TimK,
Director,
Kolb Productions,

Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net


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Jeron Coolman
Re: AJA HDP
on Jun 13, 2007 at 6:13:01 pm

Thanks Tim!

Its good to know I'm not loosing my mind...

...well loosing more of it than I thought :)



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David Mack
Re: AJA HDP
on Jun 14, 2007 at 6:41:27 am

Thanks Tim,

Can I just ask two quick questions...

1. When you use a 1080P signal via the HDP converter, does it map pixel for pixel (ie you have a black band at the top and bottom of your 24" ) of does it stretch the image across the full (1200) vertical resolution?

2. What refresh rate do you get on the LCD monitor? Can you get it to display at 50Hz progressive or does it interlace or.....? Not talking 50Fps of footage, just the refresh rate of the lcd via the hdp.

Thanks

David


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Tim Kolb
Re: AJA HDP
on Jun 19, 2007 at 1:59:53 am

Hmmm...it's been a while since I've used it, but I believe it has black top and bottom since the monitor is 1920x1200 and the raster is 1920x1080.

All LCDs are progressive...interlace actually doesn't look very impressive on many of them...progressive should be fine.

As far as refresh clock...when you have a 50Hz video system (Europe, etc), that would be the interlace "field" rate...progressive "frame" rate would be 25Hz. I'm not sure how the monitor handles the clocking issue. The cinematographer I've worked with didn't like how his HVX200 looked on it...could have been framerate. I'm not hung up on that just because I knew what the camera was doing as far as frame cadence is concerned...I wanted to see focus.







TimK,
Director,
Kolb Productions,

Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net


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David Mack
Re: AJA HDP
on Jun 19, 2007 at 6:25:35 am

Thanks Tim,

Regards LCD's being progressive - yes, that's why I was somewhat surprised to find that the Black Magic system drove it in interlaced. In Europe, being 25P Fps, the best solution would be to deliver 25 Frames per second but refresh the screen twice per image, to give you a rock solid 50Hz refresh. I'm going to be trying it out when my reseller has it sorted.

Thanks again.



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Tim Kolb
Re: AJA HDP
on Jun 20, 2007 at 6:30:17 pm

It drives it in interlaced?

I don't think you can even do that via DVI. I think progressive is all you've got.

When you put interlaced in it and display it progressive, that starts to look a little chopped, but it's the footage, not the pipeline. Computer displays and display drivers are progressive.




TimK,
Director,
Kolb Productions,

Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net


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Jeff Brown
Re: AJA HDP
on Jun 20, 2007 at 8:48:03 pm

A while back I had asked Black Magic tech about the HD-Link and interlaced display. It does not display interlaced. It converts interlaced to progressive display.

The only interface for LCD display I know of that will show you if you have field reversal, or interlace artifacts, i.e., a true interlace display, is the eCinema Systems EDP100, and it's standard-def. I _hope_ there are others! But that's the only one to date that I've been told by the manufacturer that "yes, you will see interlace twitter if it's there".

Wish I knew more about the new crop of HD monitors (Like the JVC).

-jeff


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David Mack
Re: AJA HDP
on Jun 21, 2007 at 8:07:50 am

Hmmmm. OK, maybe it's not interlacing in the true sense (LCD's just can't as there's no bleed I'm guessing) but it doesn't seem to draw it from top to bottom line by line in the true progressive way either. It does seem to draw every other line and then do a second scan to fill in the others. You can see this on horizontal movement - you see a feathering where every odd line is ahead of every even line (or visa versa).



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Tim Kolb
Re: AJA HDP
on Jun 22, 2007 at 8:06:19 pm

[David Mack] "You can see this on horizontal movement - you see a feathering where every odd line is ahead of every even line (or visa versa)."

That's what we're attempting to tell you...

What you have is a progressive scan display SHOWING you interlaced content. The display can't reformat your video. If it was on an interlaced display, you wouldn't see the sawtoothed edges on playback because it would display as interlaced. On a progressive display, interlaced shows exactly what you refer to...

Re-render all your content (or shoot it) as progressive, then it will look progressive...of course then it will look just a touch stuttery on an interlaced television.









TimK,
Director,
Kolb Productions,

Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net


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David Mack
Re: AJA HDP
on Jun 25, 2007 at 7:48:30 am

No, no, no. It's not that. I can spot interlaced footage! I do animation and always render progressive. So the images are progressive, however you CAN see the feathered edges - this can only mean that the odd and even lines of the image are being drawn separately doesn't it? On the blackmagic settings, the screen refresh is described as 25Hz Interlaced. That's where I see the issue arrising. If that could be 50Hz Progressive (but showing 25Fps) then I think it would give rock solid playback.


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Tim Kolb
Re: AJA HDP
on Jul 25, 2007 at 1:04:00 pm

[David Mack] "On the blackmagic settings, the screen refresh is described as 25Hz Interlaced."

...if the card is set to output interlaced, it's outputting interlaced, even if you animation clip is progressive.




TimK,
Director,
Kolb Productions,

Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net


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