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  #1  
Old 09-01-2010, 07:38 AM
Barry777 Barry777 is offline
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Suggestions on a studio video switcher please?

Hi guys,

I've finally finished putting together my state of the art (as of about 30 years ago) audio/video production setup which is all based around the VHS and/or S-VHS format. Basically, I have several top-end professional VHS machines synchronized to 16 track digital audio. Now I want to get a decent video switcher with the ability to fade from one signal to another, etc. I don't need all the super-advanced features, just want to make my productions look somewhat professional. I've been looking at some Grass Valley and Sony units, but confess I don't know anything about switchers and want to make sure it will work with my system. Here is the equipment I'm using:

(3) JVC BR-S822U (SVHS/VHS VCR)
(2) JVC BR-S800U (SVHS/VHS VCR)
(2) JVC BR-S500U (SVHS/VHS VCR)
(1) JVC RM-G800U (Editing controller for the BR-S800's and S500's)
(1) JVC RM-G860U (Editing controller for the BR-S822's)
(2) Alesis ADAT XT (8 track digital audio recorders)
(1) Alesis BRC (Master remote and time code translater for the ADAT's)
(4) SMPTE Time Code Generator/Readers
(6) Time Code Generator/Readers built into the VCR's

I'll be working primarily with Drop Frame format; the system doesn't seem to want to synchronize using any other frame rate. Since I'm processing the audio separately, the switcher doesn't absolutely have to have audio capability. Needless to say, access to the user manual is a must.

Any pointers, suggestions, compatibility issues, any advice at all on a suitable video switcher (especially if you have one for sale) will be tremendously appreciated. Thanks in advance!
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Old 09-01-2010, 06:48 PM
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Dave A Dave A is offline
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As the VHS decks do not take sync, you are looking at a digital switcher that handles NTSC via a built-in frame sync to buffer the video by one frame or so. These have been around for a long-time and are available used.

The Panasonic WJ-MX50 is a sample of the style. I found 3 on Craigslist for between $800 and a high one for $3200. I think it does audio also so you may want to look for a lesser version. JVC may have been in this game also.
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Old 09-02-2010, 12:59 AM
Barry777 Barry777 is offline
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Hi Dave,

Thanks very much for your quick and knowledgeable reply. As these are super high-end decks, they do have "SYNC IN" jacks (on the S800's) and jacks labeled "EXT REF" (on the S822's). The manual instructs the user to input a blackburst or composite video signal to these jacks, which are looped through to relay the signal to other units. In fact, these are the jacks I use to assist the time code in keeping everything locked together. For the audio, I use the "VIDEO SYNC IN" jack on the Alesis BRC (controller for the ADAT machines), and simply use the incoming video signal to initiate to sync train which does make its first stop at the "EXT REF" jack. I'm not sure if I know what I'm doing, but the entire system locks as long as I use 29.97 drop frame. I haven't tried slaving the VCR's the the ADAT's as I prefer to use the VCR for master control, but I'll assume the Sync In and Ext Ref jacks are functional since the system won't lock without them.

Anyway, I "think" I have the needed sync functionality already (though you definitely know more about it than I do). Assuming I'm already "In Sync", can you recommend a lower-end unit that can be had for a couple-three-maybe five hundred? I know that this is a very old-school system, but I'm so far into it already. I actually had placed a bid on a Grass Valley CV-100 until I realized it was designed for Betamax. Something like that for VHS/SVHS would be perfect.

Thanks again Dave!
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Old 09-02-2010, 06:13 PM
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Dave A Dave A is offline
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The sync signal is only a sort of master-clock (derived from a master color bar or black-burst generator onboard the switcher) to time the video signals together because of varying cable lengths in big analog plants...read tv stations. Each camera, machine in those days had adjustments (subcarrier phase and horizontal phase) on each device to adjust the timing of the output video to arrive at the switcher together. If all cables are equal length, they should time up closely and all SC/HZ adjustments should be about the same.

This page is a pretty good primer on how it works;
http://www.davidstringer.info/training/timing.htm

Time code works separately from sync. The JVC machines either record TC from an internal generator (which you say you have. JVC is card based) or from a master generator (which may want sync) connected to a TC input at each machine and the edit controller. Each machine may have a selector for EXT/INT TC for the initial recording. I think your JVC's may allow re-striping TC at a later time via an edit. Playback is not affected by the switch position as the editor reads the TC output signal onlyl. I'm not sure if your JVC uses separate TC connections or if it passes through the multi-pin that JVC used in the day.

The editor reads all the TC signals and coordinates the edit based on that signal only.

Your drop-frame (which you should be using) problem is curious. I would simplify the system by eliminating some items to see if full functionality comes back. I do not know about the Alesis system so I would start there. You may have some conflicting TC running around.

As for a switcher, JVC made a simple 2RU panel in the early 80's and I used to have one. And of course, I forget the model number but if enlightenment comes to me I will add it.

It had 5 inputs, 2 outputs, luminance key input (no alpha channel), and was a full sync-generator (base-band black) as well with some obscure sync signals that only ancient guys would know. It had a simple mix bar or cut button and a downstream key button. Even some simple wipes. 1958 in a 1982 box.

I think it had multiple sync outputs for each machine if needed using the internal sync generator for each device. It also had a wonderful input 5 function. By connecting a constant on machine to input 5, it changed to a gen-lock switcher allowing that machine to become the sync generator to which all other devices on inputs 1-4 to use as a reference. In effect, gen-lock pushes the sync source upstream somewhere. That allowed you to connect video only to 1-4 and skipped the sync cables to those machines. It was great for skipping all the sync cable connections. Again, I am not sure about how the JVC multi-pin connections fit in to this concept.

Gen-lock was widely used by stations to lock to the network as a sync source so any dissolve in and out of network was properly timed and the dissolve was smooth. Not timed to net would have given you a huge horizontal jump at the end of the dissolve as you re-joined your local sync. Not to mention the SC color shift.

It got even more complicated with football remotes where the network was locked to the remote truck at some stadium somewhere. The whole chain depended on the tv truck sync. Truck>network>local station. That made switching between stadiums an adventure as the sync source changed and could be a big lurch if done live-on-air. It was usually hidden with a station break but that would be a problem for the station locked to the network while the network switched. Someones commercial usually broke up on the air.

Uncross your eyes now and keep trying and let me know how it goes,
Dave A
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Last edited by Dave A; 09-02-2010 at 06:21 PM.
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  #5  
Old 09-02-2010, 08:53 PM
Barry777 Barry777 is offline
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Hi Dave,

WOW, that is one fantastic primer. I'm printing the whole doggone thing in color. As was the case a month or two ago, I'm asking questions I don't understand the answers to for lack of knowledge at the more basic level. I think for now, I won't worry about a switcher and will instead do a lot of reading and learning - then maybe I won't need as much guidance.

The good news is that the system is working, and I can at least do what I had planned - synchronizing multitrack audio with video.

Thanks again for the primer - it's the "book" I've wished I could find. It seems that video editing is such a vast field when you consider all that is involved, and the best thing to do is learn exactly how it works in minute electronic detail in order to determine what you need for what you want to do.

Thanks again Dave!
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Old 09-12-2010, 08:34 AM
Barry777 Barry777 is offline
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I found a Sony FXE-100 for $400, which appears to have most of the cool features like fades, wipes, chroma and luma keying and God only knows what else. It's also an editing controller for 2 players and one recorder and has time code readouts for all 3 machines. I had checked into several models, but most were designed for higher-end work and not VHS compatible. This Sony only has 4-input busses A and B, but if I need to expand later, I also have an Extron 8 channel "punch button" type switcher to throw into the mix.

I'll probably end up paying $100 for the user manual from The Broadcast Store, but it's still a great deal for what was originally a $10,000+ switcher. Can't wait to go pick it up in the next week or two!
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Old 09-12-2010, 08:44 AM
Barry777 Barry777 is offline
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Oh yes, another really cool discovery: I had bought a Tektronix 1760 Waveform Monitor/Vectorscope about a year ago, thinking it was primarily a troubleshooting/alignment tool for color TV and VCR work. Upon closer examination of the unit and user manual, it turns out that it was designed exactly for the work I'm doing with 8 loop-through video inputs, vector and lightning analysis (composite and component), and even has audio phase and time code analysis functions - along with zillions of other features I don't yet understand.

Now THAT was a very nice coincidence! That helps to make up for the few pieces of gear I've purchase that turned out to be useless because I didn't learn enough about it before buying it.
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  #8  
Old 09-13-2010, 05:29 PM
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Dave A Dave A is offline
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The FXE uses RS232 connections to the decks for machine control. It can handle A/B roll. It also has audio-follow-video for transitions. It is all digital internally with frame buffers. The luma keyer is marginally useful. It does not do a cut/fill function like a modern keyer. If you build a drop-shadow key on a computer and put it in, the keyer clip control may not see the drop shadow.

Hold off on buying the manual until I see if I can borrow a copy to copy for you.

The scope is your best friend. It will tell you everything you need about your signal.
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  #9  
Old 09-15-2010, 06:26 PM
Barry777 Barry777 is offline
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Obviously, that would be great if you could find and copy the manual, but I really don't mind purchasing one since it's a one-time expense and I'm a manual freak anyway. The guy who sold it said it's very easy to figure out, but I also want to know the more subtle features that may not be so obvious by looking at the controls.

The FXE is in beautiful cosmetic shape except that the 2 joysticks are broken off (the actual controls are still functional). It will be a fun little project making replacement sticks for them, and probably several weeks before I'll have time to really mess with it.

Anyway, thanks again Dave!
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