Zero Latency Video of Conductor

neergmas

neergmas

Member
I work at a college and my day-to-day is managing the video studio and equipment for the communication department, but my undergrad was in theatre, so when the theatre dept. puts on a musical and wants video monitors for the conductor & cast, I get to cross the street and play in the space I want to be in.

The usual set up that they've gone with since I've been here (this is my 4th year) is the band not in the pit, but rather upstage center, hidden quite a bit by the set. The conductor faces the back wall of the stage, so cueing the actors is impossible without video intervention. The trouble is that there's latency between the conductor's hands coming down on stage vs. what's seen on the monitor.

The set up that they had in place before I was hired and that I've been replicating since is as follows:
There is a flat screen tv mounted over the house, accessible from a catwalk. There is an RCA cable to the TV, which we run through a BNC connector into a Phat Cat system. The 500' cat5 (the length specified by the Phat cat unit) from that runs to the phat cat transmitter which is in the orchestra area, and there is a canon FS300 videocamera, with composite out, connected to the transmitter via another female RCA to M BNC connector. I have also had to split this signal via an RCA splitter to have a video monitor in the wings for supporting singers huddled around a mic in the wings.

Then for the conductor, I've got the same sort of system in reverse. The camera is up in the catwalk over the house near the TV, offering a birds eye view of the stage, and it all has the same cables, save that I have a small CRT monitor (cast offs from our TV studio's recent HDMI monitor upgrade) so from the Phat Cat receiver to the conductor's monitor, the connection is a BNC cable, no adaptor needed/used.

I'm working on memory from years past, and I believe there was no latency with the run from the camera of the conductor to the back stage monitors, nor any trouble with the conductor's monitor from the catwalk camera feed.

From what I piece together, the latency trouble is there because of the new TV we're using, am I correct? My predecessor had them rent the tv the first time he set it up, and then they bought it, as they assumed they'd want to use it each semester.

I anecdotally recall during my undergrad that we bought a security camera system from walmart and set that up, using long RCA cables, like 100' or more (i think) and they worked great, no trouble with the white balance with lights at full or blackout, perhaps it was a system made for looking in the dark, I recall we needed it for blackouts so that they would know actors were in place. This was over 10 years ago, so perhaps the reason I remember it working so well is that it was all "old" tvs?

So are there any suggestions, ideas, reading materials, etc on what I can do so that when the conductor gives a down beat, it's in real time on the monitor for the actors? Is it the panel tv, and should I be thinking of a way to stick some sort of "older" tv somewhere? I can take pictures of the space if it helps, because I cannot think of a place to stick a monitor where it isn't in sightlines and easily visible for actors. If you've done this and have or can take pictures, I'm wide open for suggestion!
 
Yep the biggest problem here is the Analog to Digital conversion. My suggestion (if possible) would be to use BNC Coax cables as much as possible. Look into security style systems that can have BNC out of the cameras and look for a decent size monitor that has BNC (or RCA, adapters for BNC to RCA are easy to find) input. You can still get high def picture and the latency will be a lot less.
Though getting to 0 latency will cost a lot of money, cable lengths and any devices in the way will cause latency. The trick is mitigating that latency to something manageable.
 
Is the Phat Cat system an active transmitter (i.e. requiring power) or just a passive balun (i.e. no power needed)? If it's just a passive box, then it's that's likely fine as-is and not causing any latency.

As mentioned, any analog-to-digital conversion is a potential issue. With CRT's, an all analog system works fine, including with passive baluns. Flat panel TVs always require a digital signal, including if you feed analog composite BNC/RCA video directly into the display, the TV will just convert the analog video into digital internally before it appears on-screen. If the TV's conversion is fast enough, this might work for you, but if not you'll need to convert the signal to digital with an outboard box somewhere, rated for zero latency.

If you have flat panel TV's, the best solution is using an all digital system starting with digital cameras outputting SDI or HDMI, and then transmitting that digital signal to the displays without using any analog. Professional monitors with SDI inputs typically have zero latency, but consumer flat panels using HDMI may depending on the model. displaylag.com actually measures and posts the latency of various displays when fed a digital signal, it's gotten better over the past few years. There's no data I know of for measuring the latency of displays when fed an analog signal though.
 
Thanks for the help so far, it's helping me process ideas. The phat cat system is powered. Caused me some headache last year as one of the power supplies went missing and it uses the oddest thing, 4 pin cable like a color scroller power supply...

As the flat panel tv that's hung is in a great spot, easy for actors to see and out of audience sight, i think I'd like to be able to stick with that. In theory, I can stick to analog cameras for the conductor's small monitor of what's going on onstage, and perhaps get them to invest in a small panel tv monitor for backstage (and dare i suggest another downstairs in the green room?)

The trouble I see then is running the signal from the camera pointed at the conductor to all my other monitors. I know hdmi cable really doesn't like more than about 25/50 feet, and in our classroom tech installs, we use hdmi over cat 5. As we set this up each semester, perhaps I can get it to where I can leave permanent runs for the tvs and just need to plug in some cables.

Thank you for the link, @AlexDonkle I'll check out the panel they have up there. Though I'm really hoping they have the manual or something accessible, because I don't fancy needing to go up 20 feet in the air to squint for a model number on the back of this thing!
 
Digital equipment is much more likely to add latency than analog equipment. A major reason for this is that digital signals are much easier to buffer. So as you develop an all digital path, you'll want to keep latency in mind for every piece of equipment. Converting between ditigal and analog (either direction) tends to be among the highest latency processing.
 
I use a video assist for the conductor and for the performers onstage at my theatre. Usually there's a wall between the two onstage (for set and/or sound purposes - we're a small community theatre, 150-seat house) so I have two independent systems.

For the performers: an old Sony Handicam with "night vision" on a tripod aimed at the conductor - composite video into an rf-modulator type of thing that converts it to ch.3 video - down about 150' of coax cable - to an old VCR set to ch.3 converting it to composite video out - to a Vivitek consumer-type video projector shooting on the wall above and behind the top row of the audience. We call it "Big Martha," as Martha is our music director that uses it the most and, well, it's a big bright picture, easy enough to see looking over the audience and below the front lights, and it keeps performers who need the cues facing out and up, which makes a nice stage picture.

For the conductor: a $40 Win-something security camera with infrared positioned so that it gets a great look at the whole stage from one side of the house - down about 100' of whatever cable it uses (has composite video and camera power all in one cable) - to an old CRT TV on a school-type AV cart usually just on the other side of the drums in the backstage "pit" facing the conductor. I set up the shortened camera tripod for the conductor on the same cart right next to the TV (bless you, gaff tape), so it's almost like local area video conferencing - one can see the other seeing the other.

For mostly found-in-a-closet parts and a quick prayer to St. MacGyver, it's worked pretty well for a few years now.
 
I used to work at a conservatory that did quite a bit of opera, and the conductor monitoring system was always a pretty big head ache once we moved into digital/ flat screen displays. All digital systems have some degree of latency by their very nature. In order to get the system to acceptable levels all signal distribution was done via composite analogue (bnc) cable run through a composite video amp/splitter every couple hundred feet. Basically using the same cctv tech from the 90s @neergmas mentioned above. Any camera with an analogue out will serve, but your tv monitor will have some degree of latency as long as it is digital. Check out the Wikipedia page on display lag. Www.En.wikipedia.org/wiki/display_lag
 
leistico said:
I use a video assist for the conductor and for the performers onstage at my theatre. Usually there's a wall between the two onstage (for set and/or sound purposes - we're a small community theatre, 150-seat house) so I have two independent systems.

For the performers: an old Sony Handicam with "night vision" on a tripod aimed at the conductor - composite video into an rf-modulator type of thing that converts it to ch.3 video - down about 150' of coax cable - to an old VCR set to ch.3 converting it to composite video out - to a Vivitek consumer-type video projector shooting on the wall above and behind the top row of the audience. We call it "Big Martha," as Martha is our music director that uses it the most and, well, it's a big bright picture, easy enough to see looking over the audience and below the front lights, and it keeps performers who need the cues facing out and up, which makes a nice stage picture.

For the conductor: a $40 Win-something security camera with infrared positioned so that it gets a great look at the whole stage from one side of the house - down about 100' of whatever cable it uses (has composite video and camera power all in one cable) - to an old CRT TV on a school-type AV cart usually just on the other side of the drums in the backstage "pit" facing the conductor. I set up the shortened camera tripod for the conductor on the same cart right next to the TV (bless you, gaff tape), so it's almost like local area video conferencing - one can see the other seeing the other.

For mostly found-in-a-closet parts and a quick prayer to St. MacGyver, it's worked pretty well for a few years now.
Click to expand...


I would love to see pictures of it, as it sounds quite interesting.
 
I've purchased a bunch of stuff off of eBay, and repurposed a lot of stuff from my day job, when we replaced older cameras with newer ones. Yay community theatre.
I've got a video rack we roll into the 1100' space we rent. It's got switchers and Distribution Amps and Quadframers and everything we need. Everything is analog because of the latency issues.

Standard setup is:
  • FOH cam in the lighting booth. It's an Extreme CCTV EX-82, now owned by Bosch. It's analog, with a pretty powerful IR flood built into it. Designed for up to 400' outdoors, it washes the entire stage/room in IR light.
  • Conductor cam is a Fisheye cam that was designed to be an aftermarket backup camera in a vehicle. We've put this behind the conductor (18" behind their head) and it shows from the conductor's knees up to the first electric. Lately we've been putting it on the front edge of the stage, facing the conductor.
  • SR Cam - sits on top of the SR speaker stack. Small bullet-style cam, but does have it's own (weak) IR illumination. Shows from SR proscenium to OSL wall.
  • SL Cam - sits on top of the SL speaker stack. Small bullet-style cam, but does have it's own (weak) IR illumination. Shows from SL proscenium to OSR wall.
  • Upstage wing cameras as-needed, showing aerial fly crew, or anything the SM needs to watch.
We've got a triple LCD Marshall rack, each with 2 inputs. We can only view 3 cameras at once, but can A/B between inputs for a total of 6 cameras.
We've got a couple other monitors we can toss up, if needed. All have BNC.
We've got a bunch of RGBHV BNC cable, which allows 5 composite signals. Rental houses are selling it off in favor of CAT5 solutions. You can get 100' chunks pretty cheap.

We'll always use the FOH cam. Sometimes we've got no SM, so the LX Op is calling the show. They get a monitor up in the booth, and simply use the camera to watch the stage during blackouts. These shows have little to no set pieces, maybe a drop, and some props.
Conductor and SL/SR cams get used if there's an orchestra and many set pieces.

If there's a bunch of off-stage choral parts, I'll bounce a projector off a wall OSL for the choir. (The venue's OSL is a wing, with an 8' wide x 20' tall opening to the stage.) Said wall is hidden from audience view.

We can quad-frame any combination of the cameras, and route them to the house's green room/makeup room. It adds latency, but those displays don't matter.
If there's a crazy amount of kids offstage (Aladdin Jr, etc) they're in another room 60' from the green room, so I throw up a 42" LCD and let them watch the show from there.
 
So, I am slightly confused here. If there is any latency, it should only be a few ms. So much so that it shouldn't really be that much of a problem unless the actors are having that much of a reaction time issue. Even allowing for the physics of sound to reach the actor. That time would be longer than the delay of the video system. So there must be some delay in the Phat Cat system not just the monitor.

To get rid of this issue, you could go to an all digital system. The less expensive system would use Cat5e or Cat6 cable, but would require two separate runs that have to be plugged into the correct jack every time. Easy to get around by labels or leaving it permanently together. The other, and definitely more expensive option would be using HDMI to SDI via mini converters like BlackMagic or AJA. We use them for IMAG and video systems for large conferences and I can't say that I have seen lag, at least not noticeable. Max run for SDI however for this signal is 250' I believe. You can put a re-clocker for the SDI in the middle if you need a longer run, but from what it seems, 250' might be enough. You would however need power for these converters as well where there are Cat5/6 converters that I think don't require power (not actually sure how that works though) but the ones Monoprice has is a max length of 98' from what I have read. I am not sure how you would extend that to be the distance you need, but I am sure there is a method to do that.
 
The most recent video I saw where this was evident, was a lip sync battle on Jimmy Fallon. Watch the IMAG behind everyone.

Lip Sync Battle with Will Ferrell, Kevin Hart and Jimmy Fallon:
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JFutty90 said:
So, I am slightly confused here. If there is any latency, it should only be a few ms. So much so that it shouldn't really be that much of a problem unless the actors are having that much of a reaction time issue. Even allowing for the physics of sound to reach the actor. That time would be longer than the delay of the video system. So there must be some delay in the Phat Cat system not just the monitor.
Click to expand...

You'll find that actors seem to notice the latency on a flat-panel display when the conductor is also visible in the pit - they can see the real downbeat in person and also the video downbeat on the screens and it doesn't line up and there are complaints.

It may be shocking, but the Broadway and Off-Broadway markets are still using analog systems and a lot of them still use huge CRT monitors hung in the house for the conductor shots. We see a lot of cameras like the Panasonic WV-CP500 for FOH shot and the Vitek VTC-EBV49/24H for Conductor (they are simply ordinary analog cameras with standard composite output) all connected via RG59 BNC or Cat5 via a BNC to Cat5 Balun with some boring BNC VDA's thrown in the mix to power the signals. Latency is in fact in the flat panel displays - the more costly the display traditionally the lower the latency. I still prefer hanging large CRT monitors everywhere just because they are inexpensive and work just fine.
 
themuzicman said:
Latency is in fact in the flat panel displays - the more costly the display traditionally the lower the latency. I still prefer hanging large CRT monitors everywhere just because they are inexpensive and work just fine.
Click to expand...

The high latency problems for flat panels mostly occur when feeding an analog signal into a flat panel TV and it gets converted to digital before displaying, or if the display's internal processing or scaling are activated. Unfortunately using a 100% digital signal from camera to TV is still much more expensive than Cat5 Baluns and analog VDA's, so it tends to be impractical in many cases.

The display latency of many gaming monitors when fed a digital signal is around 10ms which is essentially imperceptible. There's been a decent amount of research over the past few years about maximum latency values for live music at it relates to music performance over video-teleconferencing systems, which is similar to a remote orchestra. For real-time music a max latency of 25ms was generally agreed to work well with most musicians. For reference a single frame of video is 33ms.
 
The problem is that in many cases one cannot turn off the internal processing, scaling etc...
 
Although you usually can't turn off internal scaling, you can minimize its effect on latency by sending the display its native resolution. Once it discovers that it doesn't need to process the signal in that fashion, it will usually not process the signal.
 
Morte615 said:
Yep the biggest problem here is the Analog to Digital conversion. My suggestion (if possible) would be to use BNC Coax cables as much as possible. Look into security style systems that can have BNC out of the cameras and look for a decent size monitor that has BNC (or RCA, adapters for BNC to RCA are easy to find) input. You can still get high def picture and the latency will be a lot less.
Though getting to 0 latency will cost a lot of money, cable lengths and any devices in the way will cause latency. The trick is mitigating that latency to something manageable.
Click to expand...
Hey sorry to interrupt! But how much money would cost to have 0 latency? What kind of equipment?
 
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