Doing IMAG with two people vision mixing

January 21, 2009

Last summer I did an IMAG gig in the Glasgow Royal Concert Hall and we went for a three-screen setup. One main central screen and two side screens, with the side screens getting a separate feed from the central screen. It was a big event so we wanted maximum impact for the IMAG setup.

There were seven cameras set up as follows:

  • Two large studio cameras at FOH, one for solos and one for group shots
  • One DV cam at the side of the seating area for a side angle on soloists
  • two DV cameras at either side of the rear choir seating
  • One locked off DV cam at the back of the stage as ‘conductor cam’
  • One mini DV cam on a remote Pan/tilt head for ‘guitar cam’

In addition there was a PC graphics feed, and the projectors were 5k lumens on the sides and 6500 lumens on the centre (all Sanyo)

We set them up so that the centre screen did all the soloist and group work and the side screens were mainly instrumentalists, choir and conductor shots.

In addition we wired the two vision mixers (Panasonic MX50 and AVE55) so that the centre screen output (MX50) could also be fed as an input to the side screens (AVE55). This meant that we would choose to have all thee screens with the same shot (or graphic),  or split them to be different feeds.

I’ve done this kind of setup before and it’s a real brain-twister to get your head around the setup and to be able to concentrate on driving two different sets of screens at the same time. This time I decided to try something different and ended up having two people vision mixing, which was a first for me.

I operated the centre screen mix and directed, while my trusty colleague (who has done plenty vision mixing on his own) operated the side screen mix.

So, how did it go?

Well, you can judge for yourselves on this rather wobbly handycam footage shot by one of the artist’s associates

and here’s another clip


Overall I was very happy with the results over the three nights – the first night was solid but not exceptional, while by the third night we were hitting all the cues and really working flawlessly.

I would highlight a number of important factors that make this kind of thing work:

  • We had prepared a detailed breakdown for all songs of intro details, solos, instrumentals, etc. all laid out in an easy to read form.
  • We had a full rehearsal and 3 nights of concerts to build on, so we had a chance to make notes and improve.
  • We were located in a separate room so could communicate easily.
  • My colleague and I had worked together many times, knew each other’s styles and had a certain intuitive way of working together.
  • We avoided both cutting to different shots at (or near) the same time, as that was too hard to sync and looked a bit weird.
  • We paced out the show so that we didn’t over-stretch ourselves, i.e. the first three songs were the same on all screens, then we split for a couple, then song words on all three – etc. Just enough to break it up and to give the audience a range of stimulus so they wouldn’t get bored with it.
  • We also had very good camera operators who coped well with having two voices in their heads calling shots (and sometimes disagreeing!!)

Finally using the Matrox Dualhead2go for a live event

December 19, 2008

Some of you may recall that I wrote a couple of years ago about the Matrox DualHead2go box that can let you drive two monitors (or projectors) as if they were a single super-wide screen.

Since then they have expanded the range to include analogue VGA units, digital DVI units and also a 3-way unit called (unsurprisingly) the triple-head2go

Well I finally got hold of one on ebay (if you wait long enough, everything becomes affordable!!) and tried it out at a recent live event. It pretty much worked exactly as you would expect.

Projector setup was two Sanyo XP100 6500 lumen projs back projecting  onto two 10’x7.5′ screens cable-tied together.


We were then driving the Matrox box from a MacBook Pro which was quite happy dealing with a single 2048×768 screen, and running VGA cables to the two projectors. It was important that the two projectors were the same make and model so they matched pretty well without too much tweaking.

We used Apple Keynote as the main display software, dropping pre-rendered 2048×786 quicktime h.264 movies into Keynote and playing them back to the VGA output.

Movies were created in Apple Motion, using a combination of custom motion graphics and also some HDV video and high res stock photos from  cropped to fit the screen aspect ratio. For ‘sing-a-long songs’ we put words up on both halves of the image (i.e. both screens) to make sure everyone could see them.

It all worked remarkably well. The superwide movies played smoothly and we even keyed song words over the top of movies in Keynote which looked very slick. We got lots of positive comments from audience members.

Here are some shots of the stage showing how it looked.


large still used as backdrop

large still used as backdrop


big closeup still on back screens

big closeup still on back screens

We had no real issues, except that we were using a longer USB cable for the power to the matrox box and got a little bit of banding on the screens at times, so for again I might look at getting a separate power supply for it.

So there is a super-cheap way to get a widescreen effect for graphics.

Colour correction for rubbish projectors – Part 1

August 16, 2008

Hey – don’t all die of fright, but I’m posting a new post here again.

I won’t bore you with a detailed explanation, but suffice to say that a young family and a new job in a different city, house sale, purchase, rennovation etc. etc. meant that VLOBLIVE posts weren’t high enough up my priority list to surface for a long time.

Anyway – enough excuses –  how about a post, you all say…

Well I was finishing off a video for showing in a Church today and the church in question had a rather limited video projector – I think it’s around 2000 ANSI lumens and it doesn’t cope too well in strong sunlight.

I was thinking how to colour correct for this and thought I would note down my musings here.

This first post concentrates on preparation…

Read the rest of this entry »

Great projector calculation info at

March 22, 2007

I don’t usually post ‘hey look at this on the web’ type posts here at VLOBLIVE, as I like to focus on content, but this one is too good not to pass on.

Ever wondered what the throw distance of a projector is, or how the brightness is affected by the screen size etc. etc.

Pretty much every numerical calculation required to spec out a new projector is shown in the wonderful projector calculator at Projector Central .

Read on for more info on why this particular interactive calculator is so useful

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Gig Blog: Learning to say “No”.

February 13, 2007

I did a gig a while back where the organisers were VERY keen to have IMAG.

We had the gear, we had the crew, we had the time, but we said no.

Read on to understand why… Read the rest of this entry »

Understanding Video-over-Cat5 cable

February 13, 2007

 There’s a growing trend in live and installation video circles to move towards the use of Cat5 twisted pair networking cables for long video and VGA runs.

As with many new technologies, it’s easy to get caught out, so read on for a quick primer from an engineer’s perspective…

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Using iTunes for audio and SFX playback at live events

February 12, 2007

Hi all,

iTunes is a great music player app for organising your music library and buying tunes from the iTunes store. However with a few very simple tweaks it can be a very effective live audio and SFX playback system. Read on for more details…

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