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What is Live Switching?

Streaming Media Producer kicks off its "What Is...?" series tackling essential topics in the streaming media production world with a look at live switching, touching on the differences between switching and mixing, assembling the components and crew of a live switch, and the basics of "punching" a multi-camera show or event for live delivery.

Enter the Switcher

But when using multiple cameras for a live event that is either shown in the room on big screens (often called IMAG for IMage MAGnification) or shown somewhere else via broadcast, recording, or streaming, you'll need a way to switch between the different cameras as the event happens. This requires a video mixer.

A video switcher is a device that makes a hard connection between video sources and destinations. A video mixer, on the other hand, enables smooth dissolves, wipes, picture-in-picture, keys, and other effects between the live feed and other sources. But today, "mixer" and "switcher" are often used interchangeably.

A video mixing station from Grass Valley switching a football game broadcast

Think of watching any sporting event today. Multiple cameras, sometimes more than 20, are put to the task of showing different aspects of the game. The Director is the person who "calls the shots" and determines which camera is "live."

Live switching is also used in a somewhat less "live" situations called "Live to tape" where the event is something you can start and stop as needed. This event happens in front of multiple cameras, like a TV sitcom, or even a cooking show, such as the live-switched PBS program Flavors of America, which I worked on for more than a decade.

On the set of the live-switched (to tape) PBS cooking show Flavors of America

Instead of recording all the cameras and then trying to edit through all the footage later, mixing the video live, while the event happens, gives you a master tape that generally needs only a little bit of trimming to make it fit a given time slot for broadcast TV.

Components of a Live Mix/Switch

There are several pieces required to mix any live event. At the bare minimum, you need multiple cameras, a video mixer, and a director. This is about as simple a live switched event as can be. Jan Ozer detailed this setup in his series of articles on Telestream Wirecast (see "Related Aricle" links at the bottom of this page), one of the software packages that can be used to mix between different cameras inside the same computer that can record and/or stream the video to the web.

Telestream's Wirecast live-switching (and webcasting) software application

There are even "TV studio in a box" solutions which can use multiple remotely controlled camera heads connected to a touchscreen control surface. Just touching the shot you want with your finger will tell that camera to pan, tilt, zoom, and get the shot, and then, when it has stopped moving, the system will automatically mix the video to make that shot "live."

Rushworks "TV studio in a box"

Related Articles
This is the first of a three-part tutorial on using Wirecast to mix two streams of video and other disk-based content. In this first tutorial, I'll describe how to install and configure two Blackmagic Design Intensity Pro cards into an HP Z600 for switching with Wirecast.
This tutorial describes how to install and configure ViewCast's dual-channel Osprey 820e card ($1,795 MSRP; as low as $1,400 street) into a Windows system for driving two cameras within Telestream Wirecast, and discusses the board's highly functional set of utilities and SimulStream feature, which allows it to feed audio and video streams to more than one encoding application.
Streaming Media Producer continues its "What Is...?" series tackling essential topics in the streaming media and live production world with a look at IMAG, or image magnification, a common and effective way of delivering instant video projection of speakers and performers at corporate, conference, and faith-based events. We examine the technical challenges, the required gear, and the preferability of producing separate feeds for projection and streaming of the same event.