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Do CRT TVs have a "native" resolution? (re: hooking a computer to an old CRT TV)

post #1 of 9
Thread Starter 
I have a regular CRT TV inside my home-built arcade cabinet and also inside the cabinet is a regular PC running Windows. The TV is connected to the computer via an s-video cable and the resolution is set to 800x600.

Do regular CRT TVs have "native" resolutions?

Is my computer really sending my TV 800x600 resolution or is it down-converting it to 640x480 or something?

What are the advantages and disadvantages of higher and lower resolutions on a CRT TV like this?

Thanks for any help!
post #2 of 9
Native resolution for SD television would be 720*480, but you'll only achieve that using a computer or DVD source with at least an SVideo connection.
post #3 of 9
Quote:
Originally Posted by sofakng View Post

I have a regular CRT TV inside my home-built arcade cabinet and also inside the cabinet is a regular PC running Windows. The TV is connected to the computer via an s-video cable and the resolution is set to 800x600.

Do regular CRT TVs have "native" resolutions?

Is my computer really sending my TV 800x600 resolution or is it down-converting it to 640x480 or something?

What are the advantages and disadvantages of higher and lower resolutions on a CRT TV like this?

Thanks for any help!

I could be wrong, but here's what I think I know. CRTs don't have a native resolution in the way an LCD or plasma does. It does have a maximum display resolution that is determined (in part) by the dot pitch of the screen.

Also, while a TV may be able to accept a resolution such as 800x600, that doesn't mean that it can fully render it. For example, I've read where the Sony CRT-HDTVs (which were considered top-notch) could only resolve about 900 lines from a 1080i feed.

In your set-up, you're using s-video. I think s-video is limited to 800x600. Depending on your TV, you may be seeing all 600 lines, or you might not be. You'd have to put up a screen with 600 alternating lines that are 1 pixel wide. Then see if you can clearly determine each line.

I know that my 20" Panasonic looked like crap when fed a 640x480 signal from my iBook using composite cables. I'm guessing that my Panny was only able to resolve about 380 lines or so.

ft
post #4 of 9
Hi there

Do not confuse "regular CRT TV" with CRT computer monitor!
A bare CRT would not have a native resolution (up to its video bandwidth). But when you put control electronics and an interface (Composite video, component, or VGA) around it, then you've defined its performance.

S-video is a variant of the NTSC or composite video. That's 525 interlaced lines, about 4 MHz bandwidth, and the luminance signal is separated from the chroma signal.

An "ordinary" 4:3 TV might display about 300 x 480i resolution.
A "good" TV might display about 400 x 480i resolution.
You need a "really good" TV or a computer monitor and VGA to get to 640 x 480i.
post #5 of 9
Quote:
Originally Posted by sofakng View Post

I have a regular CRT TV inside my home-built arcade cabinet and also inside the cabinet is a regular PC running Windows. The TV is connected to the computer via an s-video cable and the resolution is set to 800x600.

Do regular CRT TVs have "native" resolutions?

As noted above, not in the sense of digital displays, but assuming you mean an analog NTSC TV, then it does have a "limited range of supported timings", basically it supports 525 lines, 15.7kHz H Refresh, at 59.94Hz Vertical refresh (interlaced of course), or in the more common verbage, it's "480i".

Quote:


Is my computer really sending my TV 800x600 resolution or is it down-converting it to 640x480 or something?

No, your video card is scan converting the 800x600@60p desktop to something that's approximately 640x480@60i.

Quote:


What are the advantages and disadvantages of higher and lower resolutions on a CRT TV like this?

The only advantage of running a higher resolution is that you have more desktop area.

The disadvantage is, since the TV can't resolve the full resolution, all the really fine details (desktop text) is basically unreadable.
post #6 of 9
Your CRT monitor runs perfectly on 800x600. On this resolution monitor ordinary life is increases. On other hand if your TV supports 600x400 so its obviously good for your TV.
post #7 of 9
A CRT technology TV normally actually scans at 480 lines a second. Some top of the line CRT 9" gun HDTVs are capable of scanning at 1080 lines a second, However due to line overlap they nornmally resolve about 1200 dots per line. 1080i Units with 7" guns normally resolve about 900 dots per line.

S-video is a NTSC standard 480i video signal. It is created by taking an image (picture) of your desktop which may be set at a higher resoloution such as 800x600 or possibly 1024x768.
Since it is an analog signal there can be more the 640 changes in each line so if your desktop is set to 800x600 your S-video output may effectivly be up to 800x480i.
post #8 of 9
Quote:
Originally Posted by sofakng View Post

Do regular CRT TVs have "native" resolutions?

No. However they do have a bandwidth limit, so they can effectively only display up to a given resolution/refresh rate combination.

If it's an old style NTSC TV, not designed for computer or HDTV use, it is probably limited to 525 line NTSC broadcasts, or 330 effective visible lines of resolution.

S-video only carries 480i anyway, so your video card is probably downresing 800x600 to 640x480 and then interlacing, on top of the resolution loss you'll see with your set.
post #9 of 9
Just to be clear, composite and s-video are both 480i signals. That is what "old" CRT TVs accept. This is also what the coax or antenna in is feeding. This is why the desktop displayed on a 480i CRT TV is almost unreadable while a CRT monitor is crystal clear (because it takes a progressive signal at a much higher resolution). For this reason you will probably do best if you set your desktop to 640x480 or 800x600 because at least the blurry icons and text will be big and you have a chance of reading it. Things like a text document or even the text on desktop icons are difficult to read. Even doing routine maintenance on your system can be difficult because you can't easily read the text. Video, on the other hand, will look great on a decent set. So if you are planning to use the pc for both video and pc work like surfing or word processing, you really need to run a dual monitor setup (TV out and monitor). In short CRT TVs are crappy pc monitors, but great for displaying video.

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