ไม่สามารถเล่นวิดีโอนี้
ขออภัยในความไม่สะดวก
what is Genlock or a video reference and how does it work?
ฝัง
- เผยแพร่เมื่อ 8 ส.ค. 2022
- today I'm going to talk about genlock also known as a video reference. how they work and where they are typically used and why.
sititng at my job wondering what the heck an AJA GEN10 does and stumbled upon this video. the glass of water analogy makes perfect sense to me. thank you!
thanks man
Well-explained, thanks.
great video and very weel explained. Good job
I think this analogy works really well. Basically it's the Keystone cops trying to make a bucket brigade it doesn't work very well but if you have some qualified people who've done this before and they're all singing the same song they can pass those buckets right off.
Super helpful!
Do we need to have both the blackMagic Micro-converter up down converter and another device the AJA Synch generator for the genlock stystem to work? Or just the synch-generator would be needed? 😅
Thank you so much for the explanations on the video and the full glass analogy into the next glass is awesome. 😊🤝
Sorry for the delay (lol) in replying I TH-cam is not notifying me of comments. To answer you question you will always have a minimum of 3 devices when using genlock. You will have the source device suck ask camera or my up down cross convertor you will have a destination device like a switcher or or video wall and a genlock generator like the AJA to tie them together.
Past that if you get into matrix and other intermediate devices that carry the signal along the way to it's final destination you would connect that to the genlock generator as well.
Genlock is a standardised thing if you go on B&H or ebay you can find them from every manufacturer under the sun.
Thanks for the question and feel free to ask as many as you need. Or make a video and post it in the comments I'll try to reply when I have time.
Great explanation, really simplifies it for my feeble monkey brain 😂👍 might be a silly question, but where in the chain does the sync generator need to go? Say you've got a larger signal chain with matrix and switchers etc, is it just a case of ensuring that they are all connected to one another's genlock i/o, so that the sync generator is basically daisy chained into the chain, wherever it may physically lie, or does the generator need to be at the top of the chain so that everything downstream is connected to it? If that makes sense? I.e would the camera be connected directly to the sync generator, and then everything downstream is also synced, or could you place the sync gen anywhere in the chain, so long as all the devices are plumbed in to one another too? (As I type this and thinking it through I'm thinking it's the latter, since the first scenario assumes you only have one camera) hope that makes sense, sorry if it's a dumb question!
It's not a dumb question at all.
Everything must get the signal from the sync generator (at the same time) and when I say at the same time I mean the pulse from the sync gen must arrive down the cable at each device simultaneously.
Say you have a sync gen that has 2 outputs, if you need to connect a 3rd device you would have to split the signal from the sync gen in one of 2 ways.
The first way is passive. Without getting into complicated electronic teary. This is not always the best way because the signal can get unstable due to each device putting a load on the output of the sync gen and causing weird problems.
The second way is actively taking the output of a sync gen and passing it through some sort of amplified splitter. This is the ideal way of splitting the signal BUT you just added some element of delay.
This may not be a problem initially, but you can create some problems that using a sync gen is intended to solve.
Say for example you have a distribution amplifier connected to your sync gen, you had half your equipment connected to the gen direct outputs and the other half connected to the distribution amplifier. The devices connected to the DA are technically receiving the reference or sync gen signal slower than if they were connected directly to the sync gen itself.
How do we fix this?
The best way is to have all devices connect to a DA output in other words sync gen>DA>your broadcast gear. This way all devices have the same inherent delay.
I am oversimplifying this but if you were in a broadcast truck with dozens if not a hundred devices. This can snowball into a problem that can have rippling effects at scale.
The short answer is sync gen just needs to hit every device. There is no order because most devices don't even have a loop out anyway, so daisy chaining is impossible. If your device did have a loop out you would want to know if it's passive or actively being amplified and how much delay is being added to that amplification.
I hope this is understandable.
Thanks for the question.
Having half your devices on a DA and half your devices straight out of a generator really shouldn't be a concern. In fact even daisy chaining DAs should not be a problem. Nor should loop outs.
DAs and loops do not add any more latency to the system than mismatched cable lengths would. These are not doing any processing. We are in the world of analog. The only time that passes is the time it takes for the electrical impulse to pass through a few coils of copper. It's basically instantaneous.
That said, if there is a timing mismatch that is causing a problem (usually due to extremely long cable runs to and from a device), most devices that accept reference signals also allow fine tune timing phase adjustments that can dial the timing in when the device is genlocked and viewed on a proper scope.
How is there a reference at 6:05 when the camera doesn’t have any reference capability?
Because it comes through the cross converter and that has a reference input I think