The technology behind the Tänktanken Talkshow live stream

On Tuesday, May 6th we premiered Tänktanken Talkshow, an alternative to our regular podcast Tänktanken, which is run by a small group at Årstaskolan.

We streamed the event live in 720p HD on the web as well as in front of an audience. Here I thought I’d post a brief overview of the technology behind it, from camera to web. We’ve tried to build a production kit so we can create productions entirely in-house and make use of the skills we have in the building. And to do it quickly. If we can lower the barriers and make this as accessible as possible, it will also be used. That’s how we always roll. And the competencies we don’t have, we make sure to acquire. Learning new things is fun.

Cameras

The cameras we use are Blackmagic Pocket Cinema Camera with Lumix H-FS14140 lenses. The Pocket Cinema Camera is a film camera that can output a clean HDMI signal without on-screen display (OSD) or other information. We therefore bring in 1080p at 25fps into the computer. Two identical cameras were used: one on the guests and the other on the host. To get the HDMI signal into the computer we use Blackmagics UltraStudio Mini Recorder, which takes the HDMI input and gives us a Thunderbolt cable to plug into the computer, a MacBook Pro Retina.

Audio

For audio input we use a Focusrite Scarlett 2i2 external USB audio interface. The advantage is that it has two channels with phantom power (which lets you use condenser microphones), but also the ability to take a line signal, which is what we did from the mixer onstage, since everyone was using wireless headsets. Before the audio goes into the interface it passes through a compressor/limiter, a Behringer Autocom Pro-XL, for simple signal adjustment. The important part here is the limiter, since we want to be able to push the audio without it clipping.

Software

Now, when all sources go into the computer you need software to mix the video and stream it. We use Wirecast for this. The program lets you set up different types of shots, where you can easily pick and choose what you want to show. Wirecast can also ingest, for example, parts of other programs, which means you can output Twitter feeds, a Skype call or similar. For this event we streamed to the service Solidtango, which is a Swedish streaming service that I warmly recommend. Their player was embedded on the event page on our podcast’s site tanktanken.se. At the same time we also had a 42" TV on stage where we sent the entire broadcast out via HDMI from the computer.

Summary

For us this setup works excellently. What we aimed for was to find a kit that would be both affordable and easy to transport. Things to improve are lighting. Lighting is really important and even though we had a bunch of spotlights on stage, we should have placed them a bit differently. In addition, over time we’ll learn the cameras, how they work and how to squeeze everything out of them. This is what it looked like from my perspective during the evening. The big screen wasn’t used; it represented the 42" TV that stood on stage when we did the test rig.

Result

Here we see one of the episodes. It’s well worth presenting the people who made it run. Camera guest | Olof (curator) Camera host | Fredrik (media teacher) Video producer | Martin (intendent) Technical producer | Me (ICT educator) Live DJ stage | Martin (curator) The week after we also did a broadcast from Folkets Hus and the event #talasomTED, which you can find at talasomted.se. Then we streamed to YouTube. With two people it took us about 30 minutes to rig everything for the broadcast. If you have any questions, as usual, just post them in the comments.