A/V Mixing Best Practices for Live Event Streaming

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Now I'm gonna talk about the video switcher/audio switcher set up. Again, these are the kind of questions I like to get cleared with the stage manager or whoever is running the actual live event that I'm gonna be broadcasting, or webcasting in this case. And again, just knowing how many speakers we're gonna have is gonna depend on what kind of audio boards and what kind of video switcher I'm gonna use.

One of the most important things that can be difficult to patch into live events is computer-based audio. And it happens usually at the last minute. Like, "Oh no," they'll tell me, "We're just doing PowerPoint slides, no one's doing embedded video." Then we don't have to worry about audio coming because our laptop audio can be difficult to drive to both the room and a live webcast because it's coming out over HDMI and if it's embedded over HDMI, your typical audio switcher isn't gonna be set up for handling the HDMI.

So you need a way to break that out and run it to the room. Usually I will use Roland V-60HD to run audio back out from that switcher out to another audio mixer, so that it's available to use in the room if I need it to be in the room. There's any number of ways to conquer that problem, Probably the most important question when I'm doing the kinds of live webcasts that I do is, where are all the audio sources coming from--and making sure I've got the hardware to support it during the live event.

Of course, if I'm doing more advanced things like lower-thirds--which is putting people's names, titles in graphics--or any kind of graphics, during a live event, all the Roland switchers I use support DSK to of overlays, based on the green or blue, or whatever chroma key you wanna use. And so getting lower-thirds well in advance of the event--of course that's at a cost, because someone has to prep those lower-thirds, and someone has to drive those lower-thirds during the event. When I'm TD'ing, I'm often driving lower-thirds as well as switching cameras as well as monitoring my broadcast, so if I've got the budget to have other team members there, so that I don't have to be driving as much, then that's perfect.

The day prior to the live event, I do more testing with audio sync. I think that's probably one of the biggest issues when you isolate audio through an audio mixer and you're bringing it into your video switchers testing audio sync. You'll typically get anywhere from one to two to maybe even three frames of delay, depending on how many video sources you have. These days you don't need genlock to have a multicamera shoot. The video switchers will buffer one frame per video input, but that one frame can accumulate for each input depending on the design of the switcher, so you have to be able to dial it in.

Most of the good switchers, those from Roland, let you control that audio delay and you have to go in--usually I just I get these el cheapo clappers from Amazon, and we just do clapper tests. One of the things I love about the Odyssey that you don't find in the Shogun recorders or Atomos recorders is the ability to scrub audio while you're watching a playback of a recording. With the Odyssey--and that's what, if I was doing this in a workshop, I would demo this for you with actual Odyssey, I just don't travel with the gear for this session. But you can actually scrub and see your clapper peak while you're going frame by frame in the video. So I can do realtime adjustments, or near-realtime adjustments when I'm doing clapper tests at a live venue.

It will add up. If you see a delay in your recording, it's gonna pass through to all of your webcasts and everything else, and so that's another thing to keep in mind with your switching gear. Roland advertises that V-60HD as being able to drive the room and your webcasts or whatever you're doing with that switched output, but one of the problems there is you start dialing it in with an audio sync delay, that will translate to the room too. The more expensive switchers will account for this because they'll have discrete circuits to handle it.

But if I start playing with audio delay and I'm right in front of the speaker, I'll hear a delay and it's really unnerving, right? You know, it's almost like an echo, so that's why I always have a dedicated audio mixer for all my live events so it can drive the room. I can add delay on the switcher and no one in the room is gonna be the wiser.