Audio Basics for Live Video

Mar 11, 2019 9:14:00 AM

There is no such thing as an Instagram filter for your video’s sound. Great audio is an elusive goal, and you can’t fake it with automatic software. You need to have some tricks up your sleeve to ensure you capture great audio on the recording so that there’s no need for special fixing after. This becomes even more important when you’re livestreaming because there is no post-production. The live broadcast is the whole production.

In a recent post about livestreaming gear, I covered some audio products that are worth looking into. In this post, I’m going to share some practical sound and audio knowledge that you can apply to your next live video.

Capture the direct sound

There are two types of sound in any video production environment: direct and diffuse. Direct sound is the purest form of the audible content, directly from the source. This is the sound of the video subject’s actual voice, directly from their mouth. Diffuse sound is the reflection of their voice off the walls, mixed with other sounds around the space, which add up to form your video’s ambience. Sometimes the diffuse sound can be cavernous, noisy, and distracting. For livestreams of music or sporting events, a healthy balance of direct and diffuse sound will actually help your audience feel more immersed in the experience. But for video that consists mostly of people (or a person) speaking, you want to isolate the voices of the people speaking and lose the background sound as much as possible.

For most mobile devices, the microphone is located a few millimeters from the camera. As you move the camera farther away from your subject’s voice, the microphone will pick up less of what they are saying and more of the diffuse sound from the environment. This makes it harder for the audience to focus on what is being said. To isolate your subject’s direct sound, try to keep their voice as close to the microphone as you can.

For example, imagine you are at a conference and you need to livestream a seven-person panel discussion. If you set your camera in the back of the room in order to fit all seven people into the frame, don’t expect to capture the direct sound of each person talking. Instead, set your camera close to a loudspeaker if possible, and point it toward the panel. If you have any kind of show with a lot of people, arrange your talent into two rows so that more people can fit into the frame while you keep the camera as close as possible. Instead of trying to decipher garbled ambient noise coming from the stream, the audience for your live video will hear and understand what is being said.

Audio and your iOS device

Audio can enter your iOS device through three main pathways:

  1. The built-in microphone
  2. The 3.5mm headphone jack
  3. A digital Lightning or USB-C connector

Let’s take a look at each.

Built-in microphone

iPhone microphonesThe built-in microphone is the default audio input used for video creation on your device. But did you know that iOS devices actually have up to four microphones on them? Different mics are used by each application depending on the device’s orientation. To find your mics, check out Apple’s support article about locating microphones on your iPad.

The problem with the built-in microphones is that you can’t always be sure which one is being used. Also, you can’t extend your mic itself toward someone speaking because it is built into your device. To make the best of your built-in mic, keep the subject close to the camera, and don’t try to stream a speaking engagement from the back of the room.

3.5mm headphone combo jack

For iOS devices with a headphone jack, you can use peripherals with a TRRS (Tip, Ring, Ring, Sleeve) connector to inject external audio into your device. Apple EarPods feature this TRRS connector, which has four conductors that correspond to the left output, right output, ground, and mic input respectively. That white block dangling on the right earphone wire has an omnidirectional microphone in it. Using EarPods will easily improve the sound quality of your audio if you need to do a quick handheld stream. There are several manufacturers of lavalier, a.k.a. lapel, microphones featuring this connector and made specifically for mobile devices. You can even add an XLR microphone or a line level input from a mixer using an adapter such as the iRig Pre or the Saramonic SmartRig+.

Digital Lightning or USB-C connector

The third audio pathway into your iOS device is the Lightning or USB-C port. With this port, you can connect audio interfaces with Lightning adapters (such as the SmartRig+Di or the iRig Pro I/O) directly to your iOS device to add higher quality sound to your videos. Using a USB adapter from Apple, you can also connect audio interfaces that are “class compliant.” For nerds, here’s the long version of audio device class compliance. The short version is that you can connect these devices to an iOS device without having to install any special control applications or software. They just work. Audio input and output pass through the interface like a seamless extension of your iPhone or iPad. The Zoom H6 is one popular device that allows for this kind of functionality, and it’s a pretty popular choice for Switcher Studio users in the Switcher enthusiasts Facebook user group.

The golden rule of iOS audio peripherals

The most important and overlooked facet of this issue is how your device decides which audio connection to use. As a rule, the last audio interface you connect to your iOS device will take over the audio for your device. For example, if you first connect Apple EarPods to your device’s headphone combo jack and then connect a SmartRig+Di to the Lightning port, your EarPods and mic will become useless. That’s because your iOS device has switched to the most recently connected peripheral and will now use the input and output of the SmartRig+Di. This short support article from Shure about the MV88 echoes the lesson about an iOS device’s behavior when it comes to connecting new microphones.

Key takeaways

If you can, always use something besides the built-in microphone to capture the audio for your video productions. A handheld microphone is a flexible piece of gear that you can use on a variety of livestreams. Whether you’re filming interviews with multiple people or capturing quick updates from a single person onscreen, a handheld option will give you the flexibility to get the most important sound directly into your video.

Wireless mics offer the most freedom. A wireless lav can free up your hands and set your live videos apart from others. Plus, you can walk away from the camera because you aren’t physically tethered to it.

If you don’t need to be portable, build yourself a solid studio setup. Look for a nice two-channel audio interface and one or more XLR microphones. I’ve heard good things about the Shure SM7B, and you can’t go wrong with a few SM58s.

Ask others what they are using for audio in their videos. Our Switcher enthusiasts Facebook user group is a great place to connect with others who are creating live video content on a regular basis.

Jimmy Burns

Written by Jimmy Burns

Switcher Studio Video Content Producer