Understanding Switchers

By: Tim Adams

The world of production switchers can be at times amazing with the sheer capabilities that are now standard, but also confusing to know which features are important to consider and essential for your setup.

First, let’s understand what a production switcher does, which is to allow the operator to change between different sources and output that “switched feed” to a recorder, a live stream host, the display system (e.g. projector, TVs, etc.) or some other destination.

While this is the primary function of the production switcher, additional capabilities also allow for that process to be supplemented with overlay graphics using keyers, and many productions switchers can even allow you to control PTZ cameras and send commands to other equipment, introducing a considerable amount of potential consolidation, space-saving and less personnel required.

Let’s dive into key terms and capabilities you need to know when learning about production switchers and which one will be the one to choose.

Inputs/Sources:

Simply put, this is how many devices you can connect to your production switcher that will SEND signal to the production switcher.

Program & Preview/Multiview Outputs:

These outputs represent the main output (Program) that is being sent to projectors, the live stream, recording, etc. and includes all graphics. The Preview is used to make your next source “ready” and allows the operator to select their next camera shot or source and make sure it is ready to transition that source to the Program output. Most production switchers these days have opted to change the dedicated Preview output to a more utilitarian Multiview output. The Multiview shows all active sources, plus shows what is on Preview and Program-all on one screen.

A note of warning here: some smaller and less expensive production switchers only have ONE video output and you have to choose whether you want Multiview OR Program. The design philosophy behind this was that you would send your Program output via USB to a connected computer for live streaming and use the HDMI output for Multiview. Not a bad way to save some money and pass those savings on to you, the customer.

However, many churches were caught short with this during the “COVID scramble” to find live streaming equipment and flooded the forums and social media asking how they could get two video outputs from these production switchers and the answer was that they couldn’t. This is why it’s important to do your research before you buy!

Program and Preview Buses:

These are identical physical rows of buttons you can use to select your inputs, usually located in the lower left of a production switcher. Generally, you would use the top row as your Program bus (indicated by red colored buttons) and the bottom row as your Preview bus (indicated by green colored buttons). The operator can cut between sources using the buttons on the Program bus, or they can select the next source on the Preview bus and use the T-bar or fader to smoothly fade between sources for a smoother transition. There can sometimes be a button to automatically accomplish this transition so you don’t have to constantly use the T-bar or fader, but it’s not a universal feature so again, do your research as this is a very nice feature to have!

M/E:

Short for Mix/Effect, this refers to the ability for production switchers to take different sources and apply effects to them, such as a Picture-in-Picture. Effects also can refer to your overlay graphics which utilize “keyers” to achieve. Larger production switchers have multiple M/Es available, which means more graphics and effects can be applied simultaneously and introduces additional complexity and cost.

Keyer:

This is the very heart of a production switcher and there are different types of keys that can be applied with a production switcher, so let’s go through them one by one as it’s important to understand what each one does and how it fits into your workflow. It could be helpful to think of keys as layers, stacked on top of the sources and sometimes, each other!

Linear Key:

Also called compositing or alpha blending, it is the simplest to understand as it combines two separate images or sources to produce one, combined image. I often use linear keys to remove black from a PowerPoint slide for a quick and dirty overlay graphic. It’s simple and effective, but you have to be careful about which graphics and colors you use as you can also remove text outlines and darker elements, depending on the parameter settings in the linear key options!

Chroma Key:

Synonymous with green screen and blue screen backgrounds, this key is used to remove a specific color and can be used to remove any color you select. I once used a chroma key to remove a magenta bedsheet for a quick and dirty (and VERY last second) video for an event and it worked just fine.

DVE Key:

Digital video effect keying is primarily used for multiple “boxes” of sources, so if you had multiple individuals needing to be on-screen that are all remote to each other, you could use a DVE key to accomplish this.

Alpha Key:

Most often used to create partial transparency in an overlay graphic, this is a way you can create a really high-end look for your lower third graphics.

DSK:

Downstream key allows you to key a graphic or source over all sources and transitions, which means you can have an overlay graphic or source while switching the camera shots behind the key. This could be helpful in some situations, but generally we train our clients to remove keys before transitioning to a different source. It’s less intrusive and distracting for the viewer.

Putting It All Together

Now that you have an understanding of the language related to production switchers, it’s time to put that knowledge together with the other features we are finding on these units of late.

Many manufacturers also include on-board audio mixing with cameras and computers being audio sources that can deliver sound into the switcher. Audio-follow-Video switching allows you to setup your production switcher so that audio that is coming in from the cameras can be turned off when switching to the computer, for example. While this isn’t immediately useful in most live streaming systems, we like to install small production switchers into projection and display systems to provide a simple way to smoothly transition between sources. This allows volunteers to avoid changing inputs on the projectors or TVs with the remote or with a scaler; both of which tend to create quite jarring transitions and draw attention to tech, which we want to avoid.

In this use case, having the audio follow the video makes sense since we can run all sound from sources such as BluRay or computers through the production switcher and only require one input on the audio mixer at front of house. Otherwise, each source would require its own input, which could take two inputs per device!

Many switchers can also connect directly to a computer or even a network for live streaming, which can help eliminate a dedicated encoder, saving space in the booth and money!

When you’re learning how to operate your production switcher or evaluating which one to get, you will need to consider how many inputs you have now and how many you will likely have in the next few years. One thing I always try and do is connect the live streaming system to the display system so cameras can be shown on the screens, if necessary. The client doesn’t always indicate that as a need, but I have found over the years this becomes a desirable functionality at some point post-upgrade so I build it into the design at the beginning.

You really need to sit down and draw out all your inputs and outputs, think about others in the church who could benefit from being able to see and hear the service (the people in the kitchen preparing potlucks, for example, or the Mother’s Room) and then plan out how you will get signal to those locations. There may not be an immediate need, but if you build the system with the ability to grow the system in the future, that will only help you in the long run!

Spend your time and really think through the M/E and keyers, as well. Most churches don’t need more than a single M/E, which will keep you in the “affordable” category of production switchers. In fact, I’d go so far as to say that if you need more than a 1M/E production switcher, you don’t need this article to say that you know enough that you know what you do and do not need. Most churches can get away with lower third, full screen and logo bug graphics to serve all their events throughout the year.

One last word: I have been focusing on mostly hardware production switchers, but the same advice and terminology goes for software production switchers, such as vMix or OBS. You do have some additional contemplation, though, with the addition of how to get multiple source signals into the computer using capture cards, USB adapters, NDI (over the network), etc.

In the end, your production switcher is the heart of your video system and you should research it well enough that you know what you’re getting, what capabilities you will have and have a rough idea of how to use it before it arrives. T

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Tim Adams spent over 20 years volunteering in church technical ministry and now focuses on helping small churches achieve technical excellence through equipment upgrades, training, sharing best practices and teaching leadership how to cast God-sized vision.