It was with 2 days notice that the Sydney Festival informed me that they'd like some way of getting tweets onto six giant screens (each roughly the size of 240 computer monitors) that were going to be viewed by hundreds of thousands of people. So sure, how could I say no?
With such little time to burn I decided to adapt the code from Visible Tweets into a format that would be suitable for what they had in mind -- live video stream above, tweets scrolling below. In addition to the design changes, there was also the request that all tweets be moderated. I'm not a big fan of moderated tweet streams at an event because inevitably the moderator can't keep up or forgets to add tweets to the stream and you end up with a stale, lifeless display. (Sure, filter out dirty words, but there's plenty of ways to do that)
Anyway, moderation was required, and with the aforementioned constraints we didn't really have time to create an entire moderation system, so we went quick and dirty -- pull all tweets from a specific account and use retweets from that account as the signal to put tweets from other people onto the screen. It worked pretty well. This workflow had the added bonus that everyone with access to that account could retweet interesting tweets using their existing Twitter client. As they were spending most of the festival running around madly with just their mobile phones, this was quite handy.
It was quite interesting working on an event of this scale and seeing the effort that goes on behind the scenes. For Festival First Night they had well over 200 people doing stage management, crowd control, logistics, production and a whole host of other stuff. My main concern was with the audio visual systems that we'd by tying a laptop into.
I've never dealt with a fully produced A/V setup before, so it was amazing to walk into the producer's trailer and see racks of processing equipment and big monitors that combined live camera feeds, pre-taped advertisements and our little Twitter visualisation into what the audience sees out on stage.
In order for the visualisation to appear in combination with live video we used a chroma key to separate out the background. This meant that I wrote my Flash app to sit on an eye-searingly bright green background and the A/V guys masked out that colour and put live video underneath. It worked amazingly smoothly, and with full alpha transparency!
With virtually no time for testing it was inevitable that a few hiccups would strike on the day, but I'm kind of used to being huddled out the back of a stage furiously trying to debug stuff that's happening on the screen right now. I'll spare you the details and offer two items of advice: 1. Never rely on an Internet connection at a public event; 2. Throttle your API calls.
But those are all memories that are easy to reminisce over when you're sitting on the grass of the Domain watching tweets flow across the screen. And to make it all seem so much smoother than it was, I've compiled a video of the outcome, which you can see below. At the end of the day, all that really matters is happy organisers, and a happy audience.