Running a hybrid disputation on Zoom

Yesterday, I wrote about Agata Zelechowska’s disputation. We decided to run it as a hybrid production, even though there was no audience present. It would, of course, have been easier to run it as an online-only event. However, we expect that hybrid is the new “normal” for such events, and therefore thought that it would be good to get started exploring the hybrid format right away. In this blog post, I will write up some of our experiences.

The setup in the hall, with the candidate presenting to the left and the disputation leader to the right.

The disputation was run in Forsamlingssalen, a nice lecture room in Harald Schjelderups hus, where RITMO is located. We had seen the need for recording lectures in the hall and had even before corona installed two PTZ cameras and a video mixer in the hall. This setup was primarily intended for recording lectures and secondary for streaming on YouTube. We actually never got around to use the new system before corona closed down the university in the spring. So the disputation was a good chance for getting the system up and running.

Forsamlingssalen, seen from the lecture podium. One PTZ camera is placed on the left wall and one in the back next to the projector. LED lights help illuminate the speakers.

What turned out to be the most challenging part of the setup was to figure out how to interface the system with Zoom. We quickly decided to use a Zoom Webinar instead of a Zoom Room. The Webinar solution is better for public events where you want to control the “production”. It is also safer since only invited panellists are allowed to show their camera and to speak.

Zoom (both the Webinar solution and regular Rooms) is in many ways a small video production tool in its own right. However, we realised that it is quite challenging to use in a more traditional multi-camera setup. Its strength is on allowing multiple people with single-camera setups to interact. We did make it work in the end, but it was quite a puzzle to get right.

People and PCs

There were four people visible in the disputation: the candidate and disputation leader were present in Forsamlingssalen and the two opponents that joined remotely. The two opponents used the normal Zoom client on their PCs, so their part was easy enough (of course, we ensured that they had good audio and video quality).

The second opponent projected on the wall during the disputation.

For the setup in Forsamlingssalen, the candidate was standing at the podium with a desktop PC with two screens and cabled ethernet. Her presentation was shown on the right screen and her notes on the left. We played with the idea of showing her presentation as a video stream through the video mixer but ended up using Zoom’s screen sharing function. That meant that we had to run Zoom on the PC, and then we could also add her image from a web camera sitting on top of the left screen.

The speaker desk, with two screens, a desk microphone, and a web camera above the screen to the left.

The image from that PC is also what goes to the projected screen in the hall. That was not so important now, since there was no audience. But for future hybrid disputations (and other events) we need to also think about people in the hall.

The hall has a nice microphone setup, with a swan neck microphone next to the PC screens and several wireless microphones. We ended up equipping both the candidate and disputation leader with wireless clip-on mics to ensure that they had a good sound coming through. The mixed microphone signal was then fed into the lecture PC to be shared through Zoom.

Two wireless microphones were used, one for the candidate and the other for the disputation leader. These microphones were connected to the PA system in the hall and sent as inputs to the desk PC to be included in the Zoom stream.

The disputation leader only had an empty lecturer desk. His image was captured from one of the PTZ cameras in the back of the hall, and his sound was captured through a clip-on mic that was connected to the sound mixer.

Cabling

The cabling in the room is set up so that there is a combined HDMI signal being sent from the podium to the video mixer. This signal contains the main image from the PC, which is also projected on the wall. It also contains the combined audio signal coming from the microphones and the PC, played over the hall’s loudspeakers. As such, we can easily tap the same signal that an audience in the hall will experience. Also, the two PTZ cameras’ signals in the hall go into separate channels on the video mixer. Below is a sketch of the cabling in the room.

The AV routing in the hall.

The original plan was to run productions from the video mixer, which can stream directly to various servers and also record on an SD card. Since we used Zoom for the disputation, however, we hooked up a separate PC in the control room, to which we fed the mixed video signal through a video grabber. This PC was then connected to Zoom, and we could switch between the two PTZ cameras in the live stream.

Research assistant Aleksander Tidemann controlling the two PTZ cameras, video mixer, and Zoom PC in the control room.

Lessons learned

Many things worked well, but we also learned some lessons.

  1. Running a hybrid event is (much) more difficult than doing a physical or online-only event. It is challenging to create something that works well both in the room and with an online audience.
  2. Having good audio is imperative. This is particularly tricky in a hybrid situation, in which you can easily get into feedback problems. Fortunately, we have a very robust PA system available with high-quality clip-on microphones.
  3. Combining Zoom with a multi-camera production pipeline is challenging. Zoom is good for connecting multiple people with one PC+camera+microphone each. Adding in a multi-camera video in one Zoom channel worked, but it is difficult to mix video for a window size you don’t know. Zoom, the viewer can choose the size and position of windows. Doing picture-in-picture on the video mixer, for example, may lead to video images that are too small to watch if the viewer is using “gallery” mode.
  4. It is challenging to be the main “producer” of a hybrid Zoom event. I have run many Zoom Room meetings and also several Webinars. But this was the first time I tried a large-scale Webinar event with a hybrid setup. It worked ok in the end, but it was tricky when I did not have access to the necessary “tools” to actually control what was going on. For example, as a host, you are allowed to turn people’s video and audio off. But you cannot turn them on again. I had originally planned to turn the camera and microphone on the lecture podium off during breaks, and then turn them back on again when we started each session. The candidate should not have to think about such things, but this meant that I had to physically go over to the machine to turn things on when we should start. That also meant that I had to sit in the hall because it would be too far to get to the control room one floor up.

A view of the hall from the control room, one floor up from the hall.

I think the final result was fine, as can be seen in a recording of the event:

In the future, however, I would probably not run such an event as a Zoom Webinar. Given that we have a nice multi-camera setup in the hall, it would be better to run it as a regular video stream. Then we would have full control over the production. The candidate could stand at the podium and focus on giving her presentation, and we could mix the audio and video in the back.

However, the challenging part with such a setup would be to figure out how to best add in the opponents in the mix. I would probably opt to connect on a separate PC (trough a Zoom Room) that would be shown separately from the presentation. Exactly how to do that will be an experiment for our next disputation!