Analog video sync

[BradC]

I remember talking about this in depth with a studio tech back when I was in high school.

The old Ampex Quad machines had a line-store, but the VHS units needed a frame store to be able to be fed as a mixable source. Editing tape to tape wasn't so difficult and even insert editing was mechanically achievable, but getting the machine to sync up to the studio timesource in even the loosest sense was limited to the vertical sync. There was absolutely no way of getting the hsync or chroma to line up. Cut to and from tape was ok, but there was no way it was going to fade/wipe.

I remember the day we took delivery of a frame store. It revolutionized production because we didn't have to dub to 2" first to give us a mixable tape source. The Quads were far more precise mechanically (having been designed for the studio) but even they needed a line store to get the sync/chroma to stay in sync.

I kinda miss the old analogue stuff, but I don't miss the hour it took to warm up and line up the studio cameras before a show. The day we took delivery of the "new" Triple CCD replacements was interesting though as they had individual RGB outputs available at the controller, so we got the Dulux colour chart and some paint samples to find out which would give us the best blue key if we used the B output on one of the cameras into the desks luma-key input. and then used that to paint up some chipboard sets. Chroma key on the cheap!

It would have been fun to spend more time with broadcast stuff. I kinda wished I'd gone that direction sometimes.

[basinstreetdesign]

Hi i would like to know how to get two analog video signals to be synced for a analog video mixer project, i have the basic understanding of what needs to be done but don't know which way to go. should i try using a phase lock loop or make a sync generator and add that to tape machine by modding a VCR to have a SYNC in to allow video mixing from two tape drives. and if so how do i do that

Kind Regards.

Justin Harris

as others have said, this really isn't possible with a domestic VCR

syncing two analog video sources is complex, especially if the source is tape

It's best done digitally with a 'framestore', where multiple inputs are digitized, combined and then output as a single video channel. Quantel did this in 1975 for TV production with the DFS-3000

i'd recommend just sourcing a cheap video mixer off ebay which will do this, i'd bet they are cheap as chips now and you'll save yourself a whole load of pain

Damn! I remember installing and fixing DFS-3001's back in 1978 in Toronto.
I spent a week in England with the Quantel design team (and driving on the wrong side of the road) learning how to do that.  The neatest part of that machine was the servo-controlled video gain pot. 

[dexters_lab]

as stated i cannot afford to use modern technology and thus must use what i have and what i have is old analog equipment which in my case i wish to use to learn what i can about Analog Video. instead of just saying its to hard or ether impossible (which i know for a fact is not the case) tell me where i can learn more e.g. books, pdfs any schematic. lets forget about the VCR syncing and more to camera syncing. i make my own analog cameras with cheap CCTV modules.

example of module:

https://www.aliexpress.com/item/New-HD-700TVL-FPV-Mini-Analog-Camera-DC12V-CCTV-Home-Security-Video-Camera-with-Mic/32849564321.html?spm=2114.search0104.3.36.2bb48164Q8NWXT&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10344_10068_10130_10342_10547_10343_10340_10548_10341_10084_10617_10616_10083_10618_10615_10307_10131_10132_5920012_10133_10313_10059_10534_100031_10103_441_10624_442_10623_10622_10621_10620_10142,searchweb201603_40,ppcSwitch_3&algo_expid=85e845c4-9f5b-47b2-ab03-30373873759a-8&algo_pvid=85e845c4-9f5b-47b2-ab03-30373873759a&priceBeautifyAB=3

nobody is saying don't experiment with analog video

but trying to engineer domestic VCRs to synchronise themselves is just an exercise in self flagellation. In playback they just 'free-run'. There are other reasons why it will be hard and those are mechanical, it needs very precise control over the tape transport to lock playback to a reference sync. You only have to see the inside of a Betacam SP deck to realise this.

if you can buy $12 aliexpress cameras then you can buy old video 'editing' systems that were very popular in the 80s and 90s, these will allow you to take two VCRs and crossfade between them and record it onto a third VCR. I am sure you'll be able to find them on ebay, flea markets, boot sales, thrift stores etc... something like this:

https://www.ebay.com.au/itm/Data-Video-Integrated-Editing-Centre/263447596943?hash=item3d56b34f8f:g:kZEAAOSwoRBaWOhz

[bopstar]

why i cannot buy that mixer unit

1: its a NTSC system
2: dose not ship to Australia. all the stuff that i can get to Australia costs to much.
3: the reason i am asking these questions is because i am making a mixer if i buy one it will defeat the hole damn point of this project

if you properly read my last respond it dose state i don't care about syncing to tape drives anymore but more syncing camera inputs. and i have been given ccd devices for free the aliexpress thing was an example of the things i use

[james_s]

Nobody was suggesting you buy that specific mixing unit, he posted it as an example of what to look for. There are similar units designed to work with PAL that were available in your region.

[BrianHG]

Just buy at least 2 matched Time Base Corrector units with external video sync input.
You may feed any cheap VCR or any other video sources into it and you can now mix the 2 analog video outputs.

It will be much harder to find a broadcast quality VCR with the feature internal, but, not impossible.

[BrianHG]

Also be careful, my old Prosumer Hi8 deck:
https://www.ebay.com/itm/Sony-EV-S9000E-Hi8-Video8-Recorder-TBC-PAL/253160429393?hash=item3af1899751:g:39UAAOSwqfpZv5rS

Does have a TBC with a perfect playback time base output, however, you cannot externally synchronize the picture out to a reference sync unless you modify the deck to it's professional counterpart.  Even so, it will only function during playback.  Not worth the 900$us price-tag.

[bopstar]

I dont want to be buying anything. just making it all from scratch, i dont intend on using any VTR's anymore just wanting to sync to live video feeds from two cameras

[BradC]

I dont want to be buying anything. just making it all from scratch, i dont intend on using any VTR's anymore just wanting to sync to live video feeds from two cameras

Most "common" syncable cameras (like CCTV with sync inputs) will frame sync. You'll still need to deal with horizontal sync and chroma. Hsync isn't so hard in a camera if it's an old one with lots of discretes as you can modify it with a pll on the horizonrtal. New asic based cameras are not so easy. Chroma sync is another whole ball of wax.

That's why old studio cameras had all sorts of wizardry in the control units to compensate for delays and cable lengths and a very specific and accurate master sync generator.

Nobody here is trying to discourage you but you need to pay heed to these technical issues unless you want to spend many hours in front of a soldering iron which is likely to lead to disappointment.

If you limit your aspirations to black and white then you'll have much better luck with a diy solution.

[bopstar]

ok ill do black and white for now. what do you think i should do. i have some old CCD cctv caneras i was given ages ago. it has a Complex multi pin dc in and a BNC Composite out, i have about 4 of these cameras but only want to fade/mix between two of them

[bopstar]

also if someone knows of any analog video cookbooks that teach how to generate basic video with discreet components and stuff, i would love to read it. something that goes into how to build up a circuit

[Alex Eisenhut]

It's "discrete", not "discreet".

http://www.swtpc.com/mholley/RadioElectronics/TV_Typewriter.htm

[bopstar]

that is not what i was talking about

[bopstar]

The CCTV camera i have is a jai cv m50. which is a black and white camera with SYNC Input

[BradC]

ok ill do black and white for now. what do you think i should do. i have some old CCD cctv caneras i was given ages ago. it has a Complex multi pin dc in and a BNC Composite out, i have about 4 of these cameras but only want to fade/mix between two of them

Most old CCTV cameras can either be synced to the 24vac power input, or have an extra input for a composite sync signal. The sync is only generally designed to be accurate enough to prevent frame roll when switching between sources on an analogue monitor, but it'll be a starting point for you.

Older cameras with line lock often had a pot to adjust the phase to ensure you could sync them as accurately as possible.

Check the data on the cameras you have to see if they have an available sync methodology.

[BradC]

The CCTV camera i have is a jai cv m50. which is a black and white camera with SYNC Input

It was common to put a quality analogue camera in the rack with no lens and a cap on to provide relatively distributable black/sync source.

[bopstar]

don't quite know what that is. main reason for why i am asking for links to documentation and books

[bopstar]

[BradC]

don't quite know what that is. main reason for why i am asking for links to documentation and books

The manual for the camera is quite comprehensive. Don't need to register to download it, just click the download link under the registration info.

[bopstar]

the pdf lacks information on the sync input

[BradC]

the pdf lacks information on the sync input

No it doesn't. It gives you the details for both H & V sync (HD & VD), the jumpers to enable/disable and even timing diagrams and amplitude requirements. The only thing it doesn't do is spell out how the H & V are related, but you can get that info from anything that explains basic genlocking.

You have several of the cameras, why not designate one a master and configure it to *output* the HD/VD sync, and use that to slave the other cameras?

[bopstar]

i will