s-video artifacts?

[VCRcomp]

Ever since I've started using an s-video connection to transfer my VHS tapes to computer, I've had a problem with some sort of artifacts. These artifacts appear only when there is a very strong color present in the video (for example, a very strong reflector lights). The best way to show it is from the VCR menu with very powerful blue "background". It doesn't matter which VCR is used or which way the video is transfered to computer or even if there is TBC1000 in between or not. Has anyone else came across this problem?

I've made a few samples from the VCR menu:


JVC VCR ----(composite)----> TBC1000 ----(composite)----> ATI ALL IN WONDER 9600pro




JVC VCR ----(composite)----> TBC1000 ----(composite)----> Sony miniDV Handycam




JVC VCR ----(s-video)----> TBC1000 ----(s-video)----> ATI ALL IN WONDER 9600pro




JVC VCR ----(s-video)----> TBC1000 ----(s-video)----> Sony miniDV Handycam

[mzil]

I'm not sure what artifact you are seeing. Please give a brief description.

[The color tint of the background seems a little different but other than that I don't know what you are seeing]

[jagabo]

The VCR has a very poor composite to s-video converter. You are getting luma/chroma crosstalk.

mzil, zoom in on the sample images. 4x point resize:

[PuzZLeR]

Is it a JVC prosumer deck? What model is it?

[edDV]

S-Video out just plays what is on the tape. The recording VCR could have had poor Y/C separation.

SVHS recorders usually have S-Video in or use a comb filter on the record side for composite Y/C separation.

[VCRcomp]

Is it a JVC prosumer deck? What model is it?

I've been using these decks:

JVC HR-E539EE
JVC HR-S7600 (TBC ON, TBC OFF, NR SOFT, AUTO, EDIT...doesn't affect the artifacts)
Panasonic NV-FS200 (AG1980) (tbc on, tbc off, NR on-off-edit...)

The test pattern was only from JVCs since the panasonic doesn't have an OSD, but when parts of the tapes with "strong colors" are being played on Panasonic, the same effect can be seen as with JVCs.

[pandy]

Use second video source (different computer with S-Video output) and verify presence of problem - looks like chroma signal is added to luminance (and not removed due of S-Video)

[jagabo]

S-Video out just plays what is on the tape.

Not necessarily. I've seen some devices with electronics only output composite video. Then they use a cheap Y/C separator to create an s-video output. This is especially true of the internal character generators on many devices.

But the s-vhs decks he's using shouldn't have this problem with tape playback.

[pandy]

True yagabo - i saw S-VIDEO output with connected C to Y on PCB with some small cap - so it was normal CVBS on both pins (cap act like highpass filter but both signals share same spectrum). Thus my idea - different source - best the digital source (like DVD player or computer with S-Video output).

[VCRcomp]

I even tried with miniDV camcorder's s-video output and it's all the same. Another interesting fact is that even on my DV camera recordings (transferred to a computer through firewire), the same kind of artifacts are shown in some cases. I'm not sure what I'm missing here, but I will upload some more images shortly..

[jagabo]

Is your software running int 16 bit color mode instead of 24 bit color? VirtualDub, for example, dithers when displaying in 16 bit color mode (though not so strongly).

I've seen lots of other people here with PAL caps that have the same problem.

[pandy]

Skip TBC - connect source directly to capture

[jbd5010]

I've been repairing and selling lots of mid-grade JVC units lately-- HR-S5901/5902/3800/4600/4800U's... these all do precisely what is shown in those screen caps above, and that's connected directly via S-Video to a LG 23" LCD TV. When connected via composite, all of these machines actually display a better picture on that TV.

Ironically I haven't scrutinized my SR-V10U's output on the same monitor... but I'm going to when I get home from work today now that I'm wondering about it.

Because I was selling them simply as basic, fully-functional machines, I wasn't too worried about it... actually, I figured it was just the way my LG monitor's scaler or A/D converter was processing the S-Video input. I don't have an old school CRT TV on hand to compare.

[edDV]

S-Video out just plays what is on the tape.

Not necessarily. I've seen some devices with electronics only output composite video. Then they use a cheap Y/C separator to create an s-video output. This is especially true of the internal character generators on many devices.

But the s-vhs decks he's using shouldn't have this problem with tape playback.

I was referring to SVHS/Hi8 VCRs that have S-Video out. VHS/SVHS/Video8/Hi8 formats record separate Y and C components to tape using the color under process. Color separation occurs during recording. Playback is output as separate components over S-Video, or summed to composite.

[jagabo]

I was referring to SVHS/Hi8 VCRs that have S-Video out. VHS/SVHS/Video8/Hi8 formats record separate Y and C components to tape using the color under process. Color separation occurs during recording. Playback is output as separate components over S-Video, or summed to composite.

Yes, I know that. I was speculating he was using a VHS deck with some kind of bolted on s-video output.

[mzil]

Skip TBC - connect source directly to capture

Agreed. Keep the signal path as short as possible using a different s-video cord, ideally a shorter, beefier one with RF chokes on it. I'd also kill any extraneous connections that may be causing a ground loop, such as the RF feed(s) for the VCR (and TV monitor), if connected, and plug all devices, including downstream ones like the audio and video monitors to the exact same AC power strip, plugged to just one AC outlet.

Alternatively, does the problem go away when the character generator is turned off? They are known to cause noise. Do you only really see a problem under this specific scenario or is a normal video image without onscreen overlaid graphics also plauged?

Research: Herringbone noise, video ground loops, ground isolators, character generator noise.

[Brad]

I think it might actually be a problem with the T200 capture chip unless someone wants to say otherwise. I've seen the same thing though not as intense.

That isn't herringbone BTW.

[VCRcomp]

Skip TBC - connect source directly to capture

Agreed. Keep the signal path as short as possible using a different s-video cord, ideally a shorter, beefier one with RF chokes on it. I'd also kill any extraneous connections that may be causing a ground loop, such as the RF feed(s) for the VCR (and TV monitor), if connected, and plug all devices, including downstream ones like the audio and video monitors to the exact same AC power strip, plugged to just one AC outlet.

Alternatively, does the problem go away when the character generator is turned off? They are known to cause noise. Do you only really see a problem under this specific scenario or is a normal video image without onscreen overlaid graphics also plauged?

Research: Herringbone noise, video ground loops, ground isolators, character generator noise.

Unfortunately no. Here is an example of video with such noise:

[jagabo]

Other people with similar problems:

https://forum.videohelp.com/threads/325507-Looking-for-artifacts
https://forum.videohelp.com/threads/324414-Datavideo-TBC1000-introduces-cross-hatching-to-picture
https://forum.videohelp.com/threads/321274-Quality-problem-caused-during-deinterlacing?...=1#post1989212
https://forum.videohelp.com/threads/266336-Luma-and-chroma-offset-from-each-other-by-on...=1#post1600102

[NJRoadfan]

I have the same problem with the blue screen on my JVC HR-S7800U's S-Video out (composite output is a nice solid blue). Actual video playback is unaffected in all cases, its just the onscreen menus. Its just that VCR too, the JVC GR-SXM260U SVHS-C camcorder's S-Video out shows no artifacts with it's generated blue screen. Have you tried bypassing the TBC-1000? There have been reported cases of some TBCs glitching out causing that block pattern.

[themaster1]

I too have the same kind of "artifacts" displayed with my vcr. I'm about to change the s-video plug next week hopefully so i'll let you know if that's better.

[NJRoadfan]

Here is the thread about TBCs glitching out and causing a similar error: https://forum.videohelp.com/threads/236244

[jbd5010]

Hey guys, it doesn't seem like we've come to a definitive conclusion with this issue. NJRoadfan's link is a thread that ends with "check with the TBC manufacturer," however on both my LG HDTV and using my ATI Theater capture card on a computer using a Hanns-G monitor, I get the above artifacts on the OSD blue screen from my SR-V10U VCR (directly connected no processing hardware).

Keep in mind this is just from the on screen display, and has nothing to do with playing anything back. Turning TBC/DNR on and off doesn't change anything.

Maybe we can conclude this is just a design flaw on the part of JVC's luma/chroma separation circuitry? Although, it think it would be a huge buzz kill to make a blanket statement that using S-video out on JVC S-VHS machines is a bad idea much of the time because it interacts poorly with many digital capture devices... also hard to believe.

I'm only testing on 2 digital display methods... maybe the LG TV and the ATI theater device have A/D or other DSP chips that produce this problem, while other chipsets don't?

[jagabo]

I think the conclusion is that the character generators used in VCRs for their OSD are very poor. But that has nothing to do with the tape playback. And some TBCs can have sometimes have similar problems but a reboot seems to fix them.

[NJRoadfan]

Maybe we can conclude this is just a design flaw on the part of JVC's luma/chroma separation circuitry? Although, it think it would be a huge buzz kill to make a blanket statement that using S-video out on JVC S-VHS machines is a bad idea much of the time because it interacts poorly with many digital capture devices... also hard to believe.

It appears that only the s-video out is affected on my JVC. Running composite into my TBC and then s-video to the computer produces a nice solid blue background.

I did some testing and the TBC seems to be whats causing the flaws seen on the blue background. Direct S-Video connection to a LCD TV and CRT TV = solid blue background. Passing the output through the AVT-8710 gave me the checker blue background on both TVs.

I think I found the culprit though. When viewing the VCR output from the TBC, I noticed a flicker (interlace bob) on the CRT, while without it the output has no noticable flicker. Its very possible that the character generator with the blue screen background is outputting in 240p and the AVT-8710 is converting this video to 480i and causing the artifacts. It would also explain why my AVermedia HD DVR has trouble displaying the menus without a TBC, it hates 240p input sources (like my NES). FWIW I get the same noticeable flicker running my NES through the AVT-8710 when normally there isn't any. I'm willing to bet that the LCD TVs having the problem treat all S-Video input as 480i, I just happen to have a rare LCD that treats it as 240p.

[NJRoadfan]

A-ha, here is a relevant thread.

https://forum.videohelp.com/threads/293509-S-Video-problem

Looks like 240p sources are what cause the black grid problem with certain upscalers/TBCs. They assume the video is 480i and it adds artifacts. (The SNES and N64 outputs 240p). I don't have a S-Video cable for my SNES, but I'm willing to bet it creates the same problems the JVC VCR blue background causes.

EDIT: ...and here is a post/thread showing a N64 exhibiting the same artifacts the JVC blue screen had via S-Video.

https://forum.videohelp.com/threads/207427-Clearing-up-dot-crawl-and-laser-rot-after-en...=1#post1188469

[jagabo]

What comes over the composite or s-video cable is always 480i. The capture device doesn't know that the source video is 240p. But a cheap 240p to 480i upscaler could cause the problem.

[NJRoadfan]

What comes over the composite or s-video cable is always 480i. The capture device doesn't know that the source video is 240p. But a cheap 240p to 480i upscaler could cause the problem.

"240p" video is a cheap hack employed by old game consoles and home computers (and VCR menus apparently), they basically don't output the half scanline at the beginning and end of the field needed for proper interlace. The result is a display with half the vertical resolution with no flicker. Its not "broadcast safe" by any means, but CRT TVs usually aren't bothered by it. The black checkerboard might possibly be a bug in the Phillips SAA71xx series ADC the AVT-8710 uses on its input, but only manifests itself with the S-video input. The Datavideo TBC-1000 might use the same ADC (can anyone confirm?), I know it was a pretty popular chip on older capture cards too.

[pandy]

Timing is also different - there is no 625 lines on screen (525 for NTSC) but 624/626 (524/526) for such video - this can confuse color decoder.
But most of digital color decoders Brooktree/Conexant/Philips have special mode for such video ie non interlace - so issue is in driver - driver should detect and set this mode - IMHO only DScaler support such feature (but DScaler is old)

[deadhead_]

You need to replace your cables and use the shortest cables. Do not see on the hardness of the cable. Chinese brothers produce thick cables with superfine and crappy wires. Try to buy good s-video connectors, good shielded and Y/C separated pairs cable and solder your own cable