How to Synchronize Multiple Cameras to a Video Switcher

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Have you ever found that one camera covering an event was not enough? You picked up a video switcher on eBay only to find that when you plugged in the cameras, the colors were all off and the picture shifted or glitched every time you tried to select a new shot? Following are the basics for timing a system for a multi-camera production.


  1. Identify your switcher as the type that needs to be timed or genlocked with camera inputs. AV mixers and some of the newest switchers have automatic timing. Just plug in the cameras and they work. Older professional switchers have connectors in back that are labeled Ref In, S/C and BB among other rows of inputs and outputs.
  2. Identify your cameras as the type that can be timed or genlocked. Only pro cameras are "genlockable". Look for a BNC connector on the camera that is labeled GEN or REF IN. Non-pro cameras will require a second piece of equipment called a "Time Base Corrector" or TBC. (See Tips).
  1. Acquire enough BNC cables to do the job. Two, equal length BNC cables will be needed for each camera. They will need to be long enough to reach from the camera position to the switcher. If you happen to have a multipin camera cable that connects to a camera control unit (CCU), then the cables only need to reach the CCU. A bunch of shorter cables will be handy for monitors and other auxiliary items.
  2. Each camera needs a reference signal from the switcher to be able to synchronize with a master heartbeat or genlock video signal. Usually this is in the form of a type of signal called blackburst (BB). Blackburst is simply a black video signal that carries the synchronization information from the switcher to external devices. Look for multiple blackburst connectors on the back of the switcher. One is needed for each camera. If there are not enough, you will need to acquire a Video Distribution Amplifier (VDA). A VDA simply takes a single video input and multiplies it into several outputs. To use one for reference purposes, connect one of the BB outs to the input of the VDA. The outputs of the VDA are now all blackburst outputs that can be used as reference signals.
  3. For each pair of BNC cables, use tape to label one cable as "REF" on both ends and the second cable "VID" on both ends.
  4. At the switcher (or VDA) connect one end of the cables labeled "REF" to any BB connector. Connect one end of the cables labeled "VID" to consecutive, numbered INPUT connectors.

  1. At the cameras, connect the cable labeled "REF" to the "REF IN" or the "GEN IN" connector. Connect the cable labeled "VID" to the "VIDEO OUT" connector. Make sure the cameras also have power. If you are using multipin camera cable and a CCU, make these same connections to the CCU instead of the camera.
  2. Find the "PROGRAM OUT" connector on the back of the switcher and use a BNC cable to hook it up to a color monitor.
  3. Find the switch on the cameras (or the CCUs) that turn on the cameras internal color bars. When you flick that switch to bars, you should see color bars on the monitor for each camera as you press the corresponding numbered button in the PROGRAM bus (row of buttons). The picture will jump a little as you punch the buttons.
  4. At this point, an engineer would use a waveform monitor and vectorscope to accurately time the system but if you had an engineer, you would not be reading this tutorial and it is beyond the scope of this "how-to" to explain the use of a waveform and vectorscope. The following method will get you close enough.
  5. Set up a "horizontal wipe". Do this by punching a button labeled "WIPE" (located near the T-bar) and also dialing in or punching a button in the "PATTERNS" section that will produce a simple horizontal transition. Moving the T-bar located between the PROGRAM and PREVIEW bus should produce a wipe effect on the monitor; probably a distorted effect.
  1. On the PREVIEW bus, punch up switcher COLOR BARS if the switcher has built in color bars. On the PROGRAM bus, punch up CAM 1. (If the switcher does not have built in color bars, set this up between CAM one in PREVIEW and CAM 2 in PROGRAM.)
  2. On camera one itself (or on the CCU) find the adjustment for "H-PHASE". This stands for horizontal phase. Usually this is a tiny screwdriver adjustment. Sometimes it is done through a menu system with arrow buttons. It may take some looking under hidden panels to find it.
  3. Tweak on the H-PHASE adjustment until the camera bars line up vertically pretty nicely with the switcher bars. Moving the T-bar up and down, there should be no jump in either of the extreme positions. (In the case that there are no switcher bars, center the bars and make little H-PHASE adjustments until there is no jumping or tearing when the T-bar is moved to its extremes. For now, ignore any color differences.
  4. Repeat this procedure adjusting camera two with the timed CAM 1 in PREVIEW and CAM 2 in PROGRAM. Work down the line until you can wipe between any two cameras without a jump.
  5. Now that the cameras are "horizontally timed", go back to camera one and find the S/C PHASE (sub-carrier phase) adjustment. You will find it in the same area as the H-PHASE adjustment.
  6. Repeat the procedure that was performed with the horizontal phase except adjust the S/C and try to match the colors, first with the switcher bars and then (more importantly) with each other. If you have no reference for color bars on the switcher, you will have to eyeball what looks right.
  7. When none of the cameras jump or tear when you push the switcher buttons and slide the T-bar and the color bars match, you can now switch back from bars to camera images. The system is timed. All that is left is to black balance and white balance and properly set the iris control.


  • Other video devices like VCRs, camcorders and cameras that do not have phase controls and external reference connectors can be timed into a switcher system with a Time Base Corrector. A TBC is a device that takes an unsynchronized signal and corrects it to synchronize with a switcher. Connect the TBC to the switcher the same way that a professional camera is connected with video and genlock cables. Time the TBC to the system by supplying some color bars to the input of the TBC (perhaps from a pro camera or a color bar generator) and adjusting the H-Phase and S/C Phase on the TBC the same way you did for the cameras. Once it is phased in, simply run a video cable from the video out of any camera, VCR or any other unsychronized device to the TBC in. The TBC "shakes hands" with the switcher for that device. A TBC also has "proc amp" controls that let you tweak in the colors, brightness contrast,etc. to match the switcher environment. These controls do not effect the timing; only the look. Professional VCRs (or VTRs) often have a built-in TBC.
  • Color bars have a certain look and color order that to the trained eye is easy to recognize. The bars represent all the primary and secondary colors with color values from lightest to darkest in order, left to right. (Turn the color knob on the monitor all the way off to see the scale in black and white. ) Try to make the second bar from the left a nice yellow.
  • BNC cables can be purchased at professional video supply stores or at Radio Shack. If you know a video engineer or technician, ask him or her to make you some.


  • S/C PHASE adjustment relies on a monitor that is set up with its color, tint, contrast and brightness controls properly adjusted. An engineer will use a vectorscope to make sure it is correct but you may have to rely on centering all the controls in the normal positions. Never adjust a monitor to make it look right while you are phasing cameras.
  • A video engineer would cringe at this timing method. If you catch an engineer cringing, ask him or her to bring their waveform monitor and vectorscope and show you how to time the system exactly.
  • Professional equipment often has "loop-through" connectors or THRU. This means that the signal connected to the input loops through the connector right next to it allowing the signal to come back out and "daisy chain through different pieces of equipment. The trick here is to make sure to terminate the THRU when it is not used. This is done by either flipping a little switch next to the THRU connector (labeled 75 ohm) or acquiring a 75 ohm resister attached to a BNC connector called a terminator available at professional video supply stores and connecting it to the THRU connection. An unterminated THRU will result in the signal connected to that device appearing "hot".

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