I wrote previously about the difficulties of finding high quality and reliable live video playout software, and the Mac-based solution we eventually went for.  The project was always planned to be a portable video production studio that could be used for live video switching/mixing (IMAG – Image Magnification – where the stage or person is projected live on the screen), live recording and streaming and video playout.

The end result is an eight input HD vision mixer/switcher based around a Blackmagic ATEM 1 M/E unit.  It’s all integrated into a 4U Studio Flyer case and ready to go at a moment’s notice.  Here’s how I went about it.

The Blackmagic Switcher

An unfortunate name for kit that’s being setup for a church.  Regardless, Blackmagic have redefined live video in the same way that multi-input USB and Firewire audio interfaces redefined studio recording.  Doing away with a control surface saves a huge amount of money, makes the unit much smaller (2U rack mount at about 6cm deep including heatsink), and opens up the possibility of remote control from an iPad.

An important thing to understand about the Blackmagic switchers is that, in common with most broadcast units, they are NOT scalers or scan converters.  That means all the video inputs need to be at the same resolution and frame rate.  So this is not suitable for visiting speakers to rock up and stick in a VGA cable from their laptop, you need other hardware that will do the standards conversion.

I got hold of the Blackmagic ATEM 1 M/E Production Switcher for £900 on eBay.  Not bad for an 8-input broadcast quality unit.  Their current units are all 4k resolution, this is one generation behind which is fine for what we’re going to be doing.  It features:

  • 4 HDMI inputs
  • 4 SDI inputs
  • Multi-view output to HDMI and SDI
  • Programme output to HDMI and SDI
  • Preview output to SDI
  • 3 SDI Auxillary outputs

If you’re not familiar with SDI, it stands for Serial Digital Interface, and in fact all of the above are 3G HD-SDI which means they’re capable of Full HD (1080i) down a single coaxial cable.  For anyone that’s ever had to run HDMI cable more than 5m you’ll understand that it’s really not suitable for live work: the connectors are awkward and fall out, the cables are springy and unwieldy, and lengths greater than 5-10m generally need active boosters or converters to CAT5 or some other format.  SDI, on the other hand, uses standard (albeit expensive) coaxial cable that’s thin and flexible and can run easily to 100m.

A particularly good feature of these switchers is the built-in multi view that shows up to 8 sources and/or outputs in a grid, with a larger preview and programme output at the top.  Using the HDMI multi view output allows connection to a standard LCD/LED TV.  Here’s me doing some testing (yes it’s a selfie) with the programme output on the top TV and the multi view on the bottom.  You can see how small the switcher is, it’s the unit flat on the floor at the bottom-left.

The “1 M/E” name means that the switcher follows the “Mix Effect” broadcast video convention, with one digital effects unit.  This means you can do picture-in-picture, split screen, and all the various cheesy digital wipes and effects that you might want.  Unlike many cheap prosumer units, the ATEM has upstream and downstream keyers for doing bugs (e.g. the BBC or Sky logo in the top corner) and lower thirds (e.g. a coloured bar with the name of a guest) and chroma keying.  It also has a proper preview output in addition to the multi view output, and the three aux outputs can follow the program, a direct feed from any input, or a clean feed of the program for recording (i.e. no bugs or lower thirds).  These features make it particularly good for my dream of live event video with streaming and recording.

By the way, don’t be fooled by the 1080i vs. 1080p thing.  As consumers we’ve all been conditioned to think 1080p is the only True Full HD.  1080i is broadcast quality and is exactly the right standard to be using.  Honest.

So, having sorted out a vision mixer, I needed to sort out some cameras.

The Canon Vixia HV20/30/40

I needed to find a camera that I could purchase new or second hand for around £100-150 each so that there would be enough budget to get two or even three.  I considered SDI security cameras, of which there are loads on the market, but I thought they would be quite limited, and it would be difficult to know which were worth having without buying loads online and then sending quite a lot back.

I discovered that there are really four aspects of a video camera to consider, aside from aesthetics/ergonomics:

  • the lens
  • the sensor
  • the recording system
  • the live outputs

I wasn’t really interested in recording in-camera (although it would be handy), but what I needed was a camera with a decent quality lens, a sensitive high resolution sensor, and clean unprocessed full quality live outputs via HDMI or SDI.  I already had a Canon 7D SLR, which has a great lens and sensor, but sadly there is no way to get a clean HDMI feed from the camera – there’s always some information overlaid by the camera’s processor.  In any case, cameras designed for stills can’t really run in video mode for hours on end because the sensors tend to overheat.  After hours of searching through different reviews and forums, I found that very few cheaper camcorders would meet my criteria… but one very cheap option stood out from the crowd.

When the Canon Vixia HV20 was first released, it caused something of a stir in the pro and semi-pro video communities.  Although marketed as a consumer camera, people quickly realised that the full-size, full-quality HDMI video output could be paired with a better external recorder to produce near broadcast quality video.  The type of sensor (CMOS) isn’t what’s usually used for TV, but it was certainly good enough for wedding and event videos, corporate training etc., and the “wobbly cam” POV shots that have become so popular.  The beauty is, because it was a high-end consumer camera, there are now many of them being sold on via eBay at rock bottom prices.  I picked up three for £100-120 each.  The HV20, 30 and 40 are all essentially the same camera with slightly different styling and software tweaks, but nothing that matters for my purposes.  The power supplies, batteries and accessories are all identical.


The Vixia is actually a pretty decent camcorder overall.  The only thing that really lets it down is the tape-based Mini-DV recording, which is old hat now with an outdated recording format and the fun of having to transfer all of the footage to a computer in real time.  The lens features optical image stabilisation and a 10x optical zoom.  Although the controls aren’t ideal for manual usage, it is possible to do manual focus pulls and other classical video eye candy with a bit of dexterity, to set the aperture and gain, and to turn off the useless internal microphone.

The next step was to look at cabling and format conversion so that I could get the right signals to the right place at a live event.  Read on in part 2.