Vision mixing basics: ATEM and vMix

By James Jones, founder of Granary Digital · Updated 5 November 2026

ATEM and vMix do the same job in different ways. An ATEM is a hardware box from Blackmagic Design with physical video inputs, and vMix is software that runs on a Windows computer. Both let one person choose which camera, slide or remote guest the audience sees. For a simple camera show with a handful of inputs, an ATEM is the steadier, simpler choice. When the show needs lots of graphics, remote guests, replays or sources over the network, vMix gets there more easily.

I have mixed live shows for more than twenty years, and these days I work freelance as a video engineer on Barco E2 and vMix. The tool matters less than people think. What matters is whether the person running it knows the show.

What a vision mixer does

A vision mixer, or switcher, takes in several pictures and sends one of them out. That is the whole idea. The details are a short list.

• Sources. Cameras, a laptop with slides, a graphics machine, a video file, a remote guest on a call.
• Programme and preview. The programme output is what the audience sees. The preview is what you are about to send. You line up the next shot on preview, then send it.
• Cuts and mixes. A cut changes the picture instantly. A mix, or dissolve, blends from one to the other over a second or two. Cut most of the time. Save the dissolve for slow moments.
• Picture in picture. Two pictures at once, such as a speaker beside their slide.
• Keyers. These lay one picture over another: names on screen, a logo in the corner, or a person shot against green screen with the background replaced.
• Audio. Most mixers include a small audio mixer, but a show with more than a couple of microphones is better with a proper sound desk.
• Macros. One button that fires a saved sequence, such as switching to a slide and bringing up a name.

A mix effects bank, written M/E, is a set of buttons and keyers that builds one picture. Small switchers have one. Bigger ones have several, so you can prepare a complicated picture on one while another is on air.

ATEM: the hardware route

Blackmagic makes a family of ATEM switchers, from the small ATEM Mini range to the larger Constellation range.

According to Blackmagic's pages, the ATEM Mini Pro has four HDMI inputs and a USB output that appears as a webcam to software such as Zoom or Teams, and the Extreme models have eight HDMI inputs. They stream over Ethernet with a built-in engine that supports RTMP and SRT, and they record to USB disks. The larger Constellation switchers use SDI inputs, ten on the smallest HD model, and Blackmagic recommends converters for HDMI cameras.

ATEM Software Control is a free app for Mac and Windows that connects over USB or Ethernet. It gives you a visual switcher, an audio mixer, stills loading and macro programming, and several people can connect at once.

What I like about hardware:

• It starts in seconds and does one job. There is no operating system update waiting to interrupt the show.
• The inputs are physical, so you can see what is plugged in.
• Operators who come from broadcast pick it up quickly.

What to plan around:

• The number of inputs is fixed. Count your sources before you buy.
• Graphics come from the media pool as stills and motion graphics. Anything that has to change live, such as scores or a long list of speaker names, usually needs another machine.
• Remote guests arrive from a computer running a call, plugged into one of your inputs.
• HDMI cable runs are short. For distance, use SDI, or a converter at each end.

vMix: the software route

vMix runs on a Windows computer. Its published requirements list Windows 10 and 11, and its page does not mention macOS. A vMix show gets its pictures in through capture cards, over the network with NDI, or from SRT feeds, plus files, desktop capture, PowerPoint and remote guests through vMix Call.

According to vMix, the software handles animated titles, data-driven graphics, virtual sets and chroma key, and it streams to several destinations at once. Instant replay is in the 4K and Pro editions. The editions include vMix 4K, vMix Pro and the vMix Max subscription, and there is a free 60 day trial, so you can try it on your own computer before you commit.

What I like about software:

• It scales. Sources are limited by the computer, not by the number of sockets.
• Graphics, replay, remote guests and streaming all live in one place.
• You can build a layout once and reuse it for every show.

What to plan around:

• It needs a computer that does nothing else. Slides, chat, email and a browser belong on another machine. The published recommended spec is a starting point, and for a multi-camera show I would go well beyond it.
• Windows updates, sleep settings and notifications are all yours to turn off before the show.
• More sources and more features give an operator more to get wrong.

ATEM and vMix at a glance

Using both

Many professional shows use both. The ATEM takes the cameras and does the cutting. Its output goes into the vMix computer through a capture card, and vMix adds the titles, brings in remote guests and sends the stream. We run vMix on a dedicated streaming computer and Blackmagic vision mixing at the studio, and our event AV team brings both to events.

The cost is delay. Every extra box adds time between what happens and what the stream shows, and your audio has to be delayed to match. Test it before the show. The latency and sync test files give you something to measure against, and NDI, SDI or HDMI explains how to pick the connection.

Which to pick

• Two cameras, slides and a stream, one operator. Either works. An ATEM Mini is simpler. vMix is easier if you want names and slides under control.
• A panel with remote guests. vMix with its call tool is the shortest route. An ATEM can do it with a computer feeding it.
• Sport with replays. vMix, in an edition that includes replay.
• A multi-camera event with long cable runs. SDI cameras into a larger ATEM, with vMix for graphics and the stream.
• A solo creator with a mirrorless camera and a laptop. An ATEM Mini, or OBS if you want to start free. Our free software list has the options.

Your first show, in order

1. List every source. Cameras, slides, a video file, guests. The count decides the kit.
2. List every output. The stream, a recording, a screen in the room. Each may want a different picture.
3. Name and number your inputs. Camera 1, Camera 2, Slides, Guest. Label the cables too.
4. Build your standard shots. A wide, a close on each speaker, slides, a holding slide for before and after.
5. Rehearse the transitions. Run every handover, video and guest in and out with the real people and the real stream.
6. Record every camera on its own if you can. The stream is one edit. Isolated cameras are next month's clips.

Our run sheet template, the live event run sheet, lays out the order of the day.

Habits that keep a show clean

• Set every camera to the same resolution and frame rate before you start. In the UK, 25 frames per second is a common choice.
• Keep a wide shot one button away. If anything goes wrong, cut to it.
• Cut on what is being said, not on a timer.
• Do not move to a camera that is still moving.
• Use talkback so camera operators know which shot is coming.
• Listen to the stream, not the room.
• Do not operate and present at the same time.

For the problems that sink streams, the five things that actually go wrong is worth reading before you start. If you are unsure whether you need a mixer at all, do you need a vision mixer answers that.

Sources

• Blackmagic Design, ATEM Mini, read 5 November 2026
• Blackmagic Design, ATEM Constellation and the ATEM family, read 5 November 2026
• vMix, Live production software, read 5 November 2026
• vMix, Supported hardware and system requirements, read 5 November 2026

Related guides

• Streaming bitrate and bandwidth calculator
• Live event run sheet template, and how to fill it
• Latency and sync test file: how to use it
• NDI, SDI or HDMI: which to use and when
• Free software for live production: OBS, Companion, CasparCG
• All guides and tools

The picture at the top of this page is an illustration, not a photograph of a client or a real job.