Page 1 of 1

Which kind of LCD TV or monitor does a CDI require ?

Posted: Mon Feb 11, 2008 6:20 pm
by arkpandora

I need some help about the following problem.

As I wanted to use my CDI on a LCD screen and wanted the same screen to serve as a computer monitor, I have just bought a Samsung SyncMaster 2032MW, a 20 inch 1680x1050 LCD TV/monitor. I have just installed the monitor and plugged the CDI into the SCART RGB input.

The result is awful : the monitor scales every CDI screen down to a low resolution (384x280 at the most), even higher resolution screens. Note that the same CDI works fine on a CRT TV or a CRT monitor.

As this is my first LCD TV, I would like to ask you three questions :

1. Is my Samsung a bad exception, or is it impossible to display a CDI properly on a LCD TV or monitor ?

In the first case :

2. Do you know any LCD monitor with video input (or possibily a LCD TV) that is able to display a CDI properly ?

3. Which requirements must a LCD TV/monitor meet in order to do so ? I expected my Samsung to work properly with a CDI, so I am confused.

Thank you very much in advance for any help !

Re: Which kind of LCD TV or monitor does a CDI require ?

Posted: Mon Feb 11, 2008 6:26 pm
by cdifan
I'm a bit confused here.
arkpandora wrote:The result is awful : the monitor scales every CDI screen down to a low resolution (384x280 at the most), even higher resolution screens.
Normal CDI video resolution *is* 384x280, although there are a few rare titles that use double horizontal and/or vertical resolution (the latter can only be achieved by turning on interlace which isn't done very often).

Assuming PAL, of course; normal NTSC resolution is even less (usually 384x240 for titles that use compatiblity mode, but it could also be 360x240).

Why do you call this "scale down"? I would call it "scale up" (assuming I understand you correctly): the LCD scales the smaller CDI picture to fill its whole screen.

Posted: Mon Feb 11, 2008 8:33 pm
by arkpandora
Hi cdifan,

Thank you for your answer.

To my knowledge, some famous CDI titles like "The 7th Guest" use a double vertical and horizontal resolution, that is 768x580. So, what my monitor does is definitely downscaling it to 384x200, by displaying only one pixel out of four in the case of a 768x580 screen. I even suspect the final resolution to be lower than the minimum CDI resolution, that is exactly 320x200, as pixels seem to be exactly the same size as a VGA 320x200 screen that uses the same space on the screen. In any case, the result is a poor pixelized version of the original screen, and disfigured as the original image was not designed for low resolution.

The monitor does not offer any setting that could disable this downscaling or activate interlacing, hence my questions.

Posted: Mon Feb 11, 2008 11:01 pm
by cdifan
To my knowledge, The 7th Guest does not use double resolution.

For the static screens it uses mostly DYUV image encoding which is not available in double horizontal resolution; for the video sequences it uses full-screen MPEG which doesn't support any kind of double resolution.

I suppose it's technically possible that some game screens use RL4 overlays (the only image encoding that supports double horizontal resolution) but there wouldn't be much point to it. As to double vertical resolution: it produced notorious flicker on most contemporary TVs and that was probably a major reason not to use it. About the only CD-i application that I've seen using it is the standard PhotoCD application.

As to the 320x200 problem, it could be that your monitor "deduces" in some way that this must be the "native" resolution of the video signal (it is a common resolution on both PCs and non-PCs) and handles it accordingly; if there are no settings on your TV I don't think you can fix this. You might try using different inputs, though (SCART vs. S-Video vs. composite), if your CD-i player has such outputs.

I'd suggest getting a different monitor, possibly taking your CD-i player with you to the store to test the image display before buying a monitor...

Posted: Mon Feb 11, 2008 11:56 pm
by arkpandora
Thank you again for your help.

Unlike other games I have played, the static screens in "The 7th Guest" do flicker a bit, and the resolution definitely looks higher in these screens than in the MPEG sequences. Would it mean that flickering is used as an artefact in order to make the resolution look higher or in order to smooth the details ?

If "The 7th Guest" is in low resolution, then it probably means that my new monitor displays the CDI in 320x200 instead of 384x280.

I will try to use the composite output of the CDI (a 210 model) instead of the SCART output.

<edit> What I have just described of "The 7th Guest" is my experience with normal picture on a CRT TV or monitor, not my new monitor.

Posted: Wed Feb 13, 2008 9:14 pm
by arkpandora
Is anyone here using a CDI on a LCD TV or monitor ? Which one and with which success ?

<edit> In addition to these downscaling problems, animation is awful. The credits vertical scrolling in "The Lost Eden" for example should be perfect : instead on my monitor it is unbearable.

I have just tested the same monitor with an Amiga computer. You were right : interlaced screens are displayed. However, although the lower Amiga resolution screen modes are not concerned by the downscaling problem, animation is still horrible. As these problems don't show up in analog VGA, I suppose that this monitor's scan doubler is simply very bad.

Posted: Wed Feb 13, 2008 11:56 pm
by cdifan
Well, now I *have* to finish the DVC support in CD-i Emulator so that I can know for sure what video modes are used by The 7th Guest.

Inquiring mind wants to know :lol: