Video output quality of Atari Computers

[amiman99]

Hi,

 

This is my first post in AtariAge forums, so be gentle.

 

I have recently acquired an External TV tuner ENXTV-X2, it is a very good tuner, to display RF ch3 or ch4 on my LCD monitor. The unit also has S VIDEO, and Composite input and output.

 

After experimenting for few hours I came to conclusion that the Video out from Atari 130XE (RF and Composite), Atari 5200 (RF) , and Atari 520STM (RF and Composite) is junk. Looks like there is a sync problem with all units. Video degradation was not made by RF modulator.

I have tried my Amiga 500 with RF modulator, Amiga 600, and Amiga 1200, with this tuner and it worked fine. Also some anolog TV programs worked fine with this tuner on the LCD monitor.

 

I have made another experiment, I used my trusty TBC (Time base corrector replaces sync signal with a new one) and PRESTO! video looks beautiful on my LCD.

 

Now..., I don't really want to run Ataris using the TBC all the time, so does anyone know how I can fix this? I was thinking the "Sima Video CopyMaster Model SED-CM" might do the trick, but I'm not sure.

[Rybags]

What's it doing? Is the screen rolling?

 

Atari 8-bit and ST computers don't output a standard VSync pulse train. In most cases, it's no problem. But some LCD monitors, HDD recorders and S-Video to VGA type boxes have trouble with it.

 

Also, for the most part, they do progressive video, not interlaced. So, one or both of these situations could be to blame. But if the Amiga is working, it would point more towards the VSync.

 

If the screen's rolling, there's practically nothing you can do. I don't think running through a VCR as an intermediary will help either as I think they only bother to amplify the signal, and don't do anything to the sync pulses.

Edited August 6, 2009 by Rybags

[Urchlay]

If the screen's rolling, there's practically nothing you can do. I don't think running through a VCR as an intermediary will help either as I think they only bother to amplify the signal, and don't do anything to the sync pulses.

 

Actually, some of the *really* old VCRs from the late 1970s or early 1980s (the all-mechanical "piano key" machines, top-loaders, usually with simulated woodgrain) were supposed to regenerate the sync. IIRC (and I may be remembering incorrectly), the ones made by Sony in those days were like that... but now that I think of it, that can't be right, wasn't Sony only making Beta back then? The ones I'm thinking of were almost certainly VHS.

 

A side effect of this is that these VCRs were supposedly able to defeat the macrovision "protection" on later commercial VHS tapes.

 

Everything I'm saying here is hearsay from 25 years ago. Take with a large grain of salt: I might have been told an inaccurate rumor in the first place (though it was a TV tech who told it to me), or I might be remembering it wrong... but it's worth looking into, if you can find a really ancient VCR (even if the tape mechanism is broken, it'll still pass the signal through).

[Rybags]

The Gen 1 Macrovision relied on the recording automatic gain circuit that practically all newer machines have (ie probably after the mid 1980s or so).

 

Normally you have black level scanlines leading up to sync, which the players relied upon to set what they think of as the base-level for luma. Macrovision just fucks this around by putting varying luminence on some of the scanlines.

 

I've come across a few newish VCRs that are practically unaffected by that type of protection... but it's all pretty irrelevant now. I turned my machine off over a year ago, chucked most of the tapes away, and have as little to do with the things as possible now.

[amiman99]

Thanx Rybags,

The screen looks like vertical scan lines with half the picture tilted by 45deg.

I was thinking sync, because with TBC, the picture was alright. BTW the VCR trick did not work also.

There are some editing Panasonic VCRs with TBC built in, those probably may work.

Edited August 6, 2009 by amiman99

[atariksi]

Hi,

 

This is my first post in AtariAge forums, so be gentle.

 

I have recently acquired an External TV tuner ENXTV-X2, it is a very good tuner, to display RF ch3 or ch4 on my LCD monitor. The unit also has S VIDEO, and Composite input and output.

 

After experimenting for few hours I came to conclusion that the Video out from Atari 130XE (RF and Composite), Atari 5200 (RF) , and Atari 520STM (RF and Composite) is junk. Looks like there is a sync problem with all units. Video degradation was not made by RF modulator.

I have tried my Amiga 500 with RF modulator, Amiga 600, and Amiga 1200, with this tuner and it worked fine. Also some anolog TV programs worked fine with this tuner on the LCD monitor.

 

I have made another experiment, I used my trusty TBC (Time base corrector replaces sync signal with a new one) and PRESTO! video looks beautiful on my LCD.

 

Now..., I don't really want to run Ataris using the TBC all the time, so does anyone know how I can fix this? I was thinking the "Sima Video CopyMaster Model SED-CM" might do the trick, but I'm not sure.

 

The Atari video signal is not junk-- it's just your device is less tolerant than normal TVs/VCRs. Amiga is doing 227/228 color clocks/line whereas Atari is fixed at 228 colors clocks/scanline and Vsync variations as Rybags mentioned.

[Urchlay]

The Gen 1 Macrovision relied on the recording automatic gain circuit that practically all newer machines have (ie probably after the mid 1980s or so).

 

Normally you have black level scanlines leading up to sync, which the players relied upon to set what they think of as the base-level for luma. Macrovision just fucks this around by putting varying luminence on some of the scanlines.

 

Hey, you actually know what you're talking about, no fair

 

(Actually, if your explanation's not oversimplified, I just learned something too)

 

I've come across a few newish VCRs that are practically unaffected by that type of protection... but it's all pretty irrelevant now. I turned my machine off over a year ago, chucked most of the tapes away, and have as little to do with the things as possible now.

 

Bleah. I have too many commercially released VHS tapes and too limited of a budget to re-buy them all on DVD (especially as I'd have to buy them all again on blu-ray in a couple years)...

 

And the BBC is taking *forever* to release some of the old Dr. Who episodes on DVD, so VHS is the only way to legally get them (or was, back when BBC was still doing VHS releases).

[ClausB]

Did you try reversing the polarity? That always worked for the Doctor!