Add/restore sync pulses (avoid TV bluescreen) with low latency?
 

TLDR: What is the lowest latency method of adding/restoring sync pulses please?

Hello you lovely people! This forum has been a big help to me in solving a very upsetting problem, thank you all, I think I am almost there, however I have reached another hurdle which I have been unable to overcome alone and would greatly appreciate some help please

This is not strictly vhs capture to digital, but I believe the issue is the same, and the closest I could find online, I hope it is ok to post this here?

I am attempting to display an analogue composite video signal on a modern LCD TV, via its composite port, and the image is displayed beautifully, however the signal is sent via analogue wireless transmitter and receiver, and occasionally the signal will degrade for a moment and cause the TV to go to black screen (the equivilent of the bluescreen of yesteryear I believe) and it will take a couple of seconds to recover, while my smaller analoge display will continue to display the image when it gets snowy or is lost for a moment, restoring the image immediately.

I was able to get the TV to behave in the same manor as the analoge display and show snow and recover instantly with the help of the pseudo TBC in an Panasonic ES10 (passthrough), however it added substantial latency, which it is critical I avoid or minimise as much as possible (for realtime gaming, not due to audio / lip sync delay)

I believe the undesirable behaviour is a result of a sync pulse being weak or lost, causing the TV to lose sync, but could be mistaken, I am new to all of this.

Is there another method of adding/restoring the sync pulses, perhaps with an entirely analogue device, that will achieve the same result without adding latency?

Or might a line TBC add only a line of latency instead of an entire frame? (sub 1ms latency instead of 40ms for PAL 25fps)
Or would the latency from each line add up to equal just as much latency as a full frame TBC/buffer/syncroniser?

I have been attempting to solve this problem for months and have bought many devices that have not solved the problem and it is really upsetting me, so if anyone has any ideas or advice it would be greatly appreciated.

One thing I have yet to try is video enhancers/stabilizers/clarifiers, might they work without adding latency? (there is no Macrovision to remove)

Many thanks in advance

TLDR: What is the lowest latency method of adding/restoring sync pulses please?

Hopefully you will get some responses from more knowledgeable folks, but I don't think a line TBC will help in your situation at all. Line TBC is specifically for tape sources--it is meant to correct situations where the lines that make up the image get skewed vertically. Frame sync is what is going to help your situation.

But, as you've seen it introduces some latency, to which gaming is extremely sensitive--milliseconds aren't really noticeable when digitizing tapes but gaming is a different story.

I think your only hope is to try some other frame sync boxes. You don't need one that specifically mentions TBC. Doing a search for frame synchronizer on ebay or other sources should turn up some possibilities. I have no idea, but maybe frame syncs meant for broadcasters and other professionals might be lower latency?

You could also try one the of the frame TBCs recommended here--the AVT-8710 or TBC 1000. But those are at outrageous prices now, without any guarantee that they would be any lower latency than the ES10.

A cheaper route would be trying some other DVD recorders. You don't need the line TBC functions of the ES10 or ES15, so maybe pick up some other models (especially if you can get them cheap at thrift stores) and see if they do any better.

Have you looked into the possibility of changing out your wireless transmitter? Maybe you can find something that uses a different frequency and wouldn't break up the signal in the first place.

Edit: I don't think the macrovision boxes will help you. I have a Sima CT-2 that I tried to use when I was dropping frames capturing a damaged tape and it didn't help at all--still dropped the exact same number of frames with it connected. So those boxes do not restore/rebuild frames--at least not the Sima ones.

You are using the most mediocre way of transmitting a video signal and you are trying to fix it by adding more unnecessary equipment, If wireless transmission is the only way, get an analog to HDMI converter and transmit the HDMI signal to your TV either wirelessly or via DLNA using your router WiFi, Some other transmitters use the power outlets to transmit video from one room to another using just the existing power wires inside the walls.

Hi and thank you both for your responses!

Unfortunately I cannot change anything else about this setup.

And anyway, I imagine attempting to send the video over wifi would incur even more latency, and also the way digital video breaks up with pixilation and freezing is not nearly as pleasant/tolerable as nostalgic static/snow :)

Powerline ethernet is another good suggestion, thank you, however I also intend to use it outside come spring, hence wireless :)

Do you think there is any chance a Frame Synchronizer might help restore/replace the Sync Pulse without having to buffer the entire frame and add a frame (40ms) of latency?

Many thanks!

No, It's not a TBC problem, it's a wireless transmission problem, The signal transmitted is no longer a composite signal, it gets modulated into a higher frequency and transmitted as such, adding a TBC is like painting a flat tire, it won't fix it. You need a better and more powerful analog transmission which costs money or a digital transmission that yields better picture and costs less.

I think that's precisely how a frame synchronizer works--it has to store the lines in a buffer and reassemble them with the proper frame signaling. So there is always going to be some delay involved. Some advertise as low as 1-2 frames (AJA's FSMini is one of them, but not only is that an investment of several hundred dollars, it requires an SDI digital input). That's why I think you'd be better off experimenting with other DVD recorders to see if any of them offer lower latency than the ES10. It's highly doubtful you'll find any published specs or discussion about that aspect of them, because it's near meaningless for their intended uses.

Maybe you could instead try some different LCD monitors/TVs--perhaps some don't have the long delay when the signal drops?

Edit: You might try turning the NR off on the ES10 to see if that makes any difference. It likely doesn't, but worth a try. The TBC itself cannot be turned off.

I want to reply with more details here, no time right now, but I need to quickly inject something...

DVD recorders all have a lag, and the ES10 is probably one of the lower delay units. Some are as much as 2s.

This situation is a reason that frame TBCs exist, and the best TBCs attempt to give a mere 1-frame delay (0.034s NTSC to 0.04s PAL). If this is for games, I'm not opposed to testing this with my SNES or PS2 (playing a Street Fighter II), but it'll take me a week or so to have time for it. I'm actually curious myself, what the delay may be in real-world usage.

Thank you lordsmurf, I thought I was losing my mind :)

Please don't inconvenience yourself by testing it for my sake, I know from changing displays and even just display settings (measing display latency with leo bodnar device) that even 20ms is very noticable, especially on some genres such as racing and FPS.

Having gone to such great lengths to find such low latency devices, the thought of having to add so much latency at the last hurdle is devastating :(

Might there be a standalone analog (composite) to digital (VGA/DVI/HDMI) converter that handles weak signal better than the one in the TV and incorporates some sort of sync generation without adding more than a few milliseconds of latency?

There are certainly such analog to digital converters that measure their latency in the tens of MICROseconds (sub 1 millisecond), such as this one:

RetroTINK 2X-Multiformat
https://www.retrotink.com/product-page/2x-multiformat

however I don't know how it would cope with a weak/missing sync signal :(

Thanks so much for all your help everyone :)

Just to clarify, TBCs are not meant for wireless transmission. I refer only to weak sync.

I used a Terk transmitter some years ago, to get cable to a kitchen TV that was impossible to wire at that counter location. The transmitter had to be line-on-sight, and had lag of several seconds.

What frequency does it use? If it's 2.4 GHz, even just running the microwave could mess up the signal. So yes, make sure the transmitter and receiver are line of sight to each other to keep the signal strength up. An ounce of prevention is worth a pound of cure!

The OP is confused between a video signal in the MHz range and the wireless modulated video signal in the range of GHz, he thinks he can fix the transmission interruptions by using a TBC that works in the video signal not the modulated high frequency signal, I did my best to explain it in my earlier post.

With the utmost respect latreche34, I think you misunderstood my initial question.
I am not mistaken, however perhaps I was not clear, so I shall clarify :)

I am not attempting to fix the transmission interuptions of the wireless signal with the TBC, I am attempting to fix the way in which the digital display reacts to them.
I am attempting to prevent the display from showing a black screen (on older displays it is a blue screen) when the signal / sync pulse is weak/lost due to the wireless transmission. (I would like it to behave more like an analog display and show a snowy image)

The pseudo TBC in the Panasonic ES10 solves the problem perfectly, which is how I know I am not mistaken, it just adds too much latency.

I since read a post stating that inside the ES10 is not a 'true TBC' (I think the term was "frame filter" or similar?), so I am hoping that it is doing more than I require (such as solving VHS issues I do not have) and a 'proper' TBC or perhaps a device I have not yet read about can solve just this one problem, inducing less latency.

So my question is:

Is there a device that will resolve the same issue (weak/lost sync pulse) but with less than one frame (40ms) of latency please?
else
Which adds the least latency please?

Thank you for taking the time to reply to my posts, it is greatly appreciated :)

You're still confused,
Let me write the diagram of the signal path and tel me which part your're struggling with or you think the interruption is occurring:

1-Video game console CVBS signal MHz (Composite) --> 2-Composite cable --> 3-Video Transmitter (CVBS signal is modulated to GHz) --> 4-Air waves --> 5-Video receiver (GHz decoded and converted back to CVBS signal MHz) --> 6-Composite cable --> 7-TV

If the signal interruption is in 3,4 and 5 it cannot be solved by a TBC, TBC cannot process such signal if you put it in one of those points. And if you put a TBC in front of the TV where it suppose to be, it cannot recover the missing information from a bad wireless transmission because the TBC expects a minimum clean video signal to fix its timing, if it's all garbled it just confuses the TBC and makes it worse.

No, TBC is 1/50 sec for NTSC and 1/60 for PAL.

I think you're the one who's confused. He's not trying to recover any missing information.

He just wants to keep his display happy by feeding it black burst when there are interruptions in the actual signal. That's what any frame synchronizer *should* do. It should be outputting proper frames no matter what is coming into it--great signal, poor signal, or no signal at all. Its job is to take whatever it gets, make proper frames out of it and spit them out at the right time. The frames may not look pretty, but at least they should be a "proper" NTSC/PAL signal.

He already stated that a Panny ES10 did exactly what he wanted to do (provided a stable frame sync)--it just introduced too much latency in the process.

There's no reason to think a TBC wouldn't do the exact same thing, and perhaps with less latency (or perhaps with more--I dunno). Seems crazy to me to spend $1000 on a TBC when less money could be spent on a better signal transmission method, but maybe OP could see if he could rent a TBC-1000 or AVT-8710 from somewhere to demo it out.

You're confused too, That's the job of sync pulse generator (genlock) not TBC. Besides he will still have the problem of recovery when the video signal bounces back on he may have a frame roll or half frame black band, the TV may still display black/blue screen due to missing video signal even if the sync is intact, That's why I said this is not going to work and a digital transmission is cheaper and better and even faster.

You have that backwards. :wink2:

That's not going to happen in 2021, nor even in 2011. Maybe 2001.

You're both making me confused. :laugh:

Again, he already said that an ES10 worked to do what he wanted, so on what basis are you trying to tell him a frame TBC won't work?

Genlock is two sync two sources together. That's not this.

Then a frame TBC should also work.
However, I think lag may be in the wireless transmit, not any TBC.

I think he said (or implied) that the ES10 caused the lag. His wireless system worked fine without the ES10--it just caused his LCD TV to go into a black screen mode whenever the signal was interrupted. He used the ES10 to keep the TV alive but then experienced the lag.

ES15 has lag, but ES10 does not -- at least mine doesn't, and I got it new back in 04/05 when ES10 came out. I'm not aware of any variations of the model.