There are lots of components that go into making a good video. Footage shot with proper lighting; appropriate camera support for the clip you're about to shoot; gentle camera motion to give depth to your shots; spot-on timing when transitioning between clips; solid color correction so that your clips have visual continuity; appropriate transition selections; and many other visual things. However, there's an aspect to great video that often gets neglected, especially by those relatively new to video: the audio.
My friend and fellow CPM writer, Mark Hanna has a great saying that I'll quote here: “In the world of video, audio is king.” And this is really true. People will tolerate poor visuals in video far more than poor audio. While the visuals deliver the emotion and context, it's normally the audio that delivers the details of what's going on. If you can't understand the audio, or have to strain to hear it, people will more quickly tune out or stop watching than if the video quality isn't great.
So, what are some of the key aspects of getting good audio capture?
Proximity
First, you always want to get the microphone as close as possible to the source of the audio you're trying to capture. Most of the time (like 99.99%), this means you do not use the microphone built-it to your camcorder.
If you are using a lapel microphone, determine which direction the person is going to be facing and attach it to their clothing such that they are facing the mic. If you clip it to the left side of their shirt and they turn and face to the right for most of the shoot, your audio will not be as good. Just make sure they aren't doing to blow into the mic when they speak through either their mouth or their nose, otherwise you'll get some nasty noise in your dialog from plosives (consonants which usually cause a lot of air to be blown out, like “B” and “P”).
Even better is the use of a shotgun mic on a boom pole. Not only will you usually get better sound, but as the microphone isn't in the frame, it provides better aesthetics as well. I use a Røde NTG1 shotgun mic and boom pole and a generic shock mount for most of my audio recording for video and have been very happy with it. It's a cost-effective mic and sounds incredibly natural, like you're just sitting in the room listening to the person speak.
Position the mic just out of frame pointing at their mouth as close as you can get it. While mic'ing from above is the most typical, think outside of the box and consider whether mic'ing from below or from the side might actually get you closer. If your subject will be stationary, I frequently use a C stand (Century stand) and pole clamp for holding the boom securely without exhausting someone by holding the pole over their head. Matthews makes a variety of clamping accessories for holding booms via a C stand.
Make sure you use a shock-mount for placing your mic on your pole to lessen the handling noise transferred to the mic from the person holding the boom. And train your boom pole operator—have them put on your headphones and manipulate the mic pole so they understand what sort of actions transfer noise into the microphone.
Audio Connection
Whenever possible, you should use a balanced audio connection from your mic to your recording device. Balanced audio is less susceptible to electronic noise/interference. Any decent professional video camera will have balanced connectors and be able to provide phantom power (a way of transferring power to a condenser microphone from the camera or other audio recorder). However, if you are using a DSLR for shooting video, these don't have balanced audio or phantom power. In these cases, you may want to invest in a separate audio recorder such as the Zoom H4N, Tascam DR-40 or the Sony PCM-D100 which CPM recently reviewed. These provide XLR microphone input jacks with phantom power.
Use Headphones
I will often do editing for clients where the footage was shot by someone else, and I've been surprised at the number of times the audio was completely distorted. Clearly the cameraman wasn't monitoring the audio with headphones, as there's no way they could have missed the issue if they were. Always wear headphones and monitor your audio recording. I actually keep a pair of cheap ear buds in each of my camera cases in case I forget to grab my good headphones from my editing suite when I head out for a shoot.
Sound Check
Do a sound check before you start shooting for real, and ask the subject of your shoot to laugh or purposely speak loudly while setting your levels. People almost always talk louder during the video capture than they do during a sound check, so get them to be louder than they think they will be when setting your initial levels, and be ready to quickly adjust during your shoot.
Also, err on the side of recording too quietly vs recording too strongly. You can bring the levels up in post without perceptible quality loss, but once your audio is clipped, you have a major problem to solve. Tools like Adobe Audition have some audio repair capability, but it's of limited usefulness. If you find yourself frequently having audio that's either clipped, or recorded in an environment with a lot of ambient noise (such as HVAC sounds), then you may need to invest in a program like Izotope RX3. RX3 does an amazing job in fixing clipped audio, removing noise in a particular frequency range, and removing background noise and even reverb. However, it doesn't come cheap—the professional version of RX3 is $1,200. It's far better to prevent the problems from happening in the first place.
Audio Processing
Lastly, you will have some audio editing/processing to do once you get into post-production. You want your audio levels strong on your video. For interviews, I always bring my audio into Izotope RX3 first if the audio has noise or clipping problems, and then into Adobe Audition to work with levels. If the audio is very clean, I might just use run-time effects applied in Adobe Premiere, but usually I use Audition.
First, I apply some amount of compression to get the levels evened out. Most of my work is with interview or presentation type videos, so I want the audio of the people speaking to be consistently strong. If you're doing dramatic theatrical-style work, more dynamic range is called for to reflect the emotion being conveyed, so I'd go lighter on the compression. If you're not familiar with compression—well, that's an entire article in itself. But in a nutshell, compression reduces the difference between your quietest levels and your loudest levels by reducing the volume by a certain ratio when the volume exceeds a specific threshold point.
For example, let's say that as I look at my audio wave form in Audition, I see that my presenter's volume ranged from a minimum average of -20 dB to the loudest at -5 dB. I'd probably set my threshold at around -18, and apply a 2.5 compression ratio. When the signal is below -18 dB, it's passed through unchanged. When it's at -15, the output would be -16.8. When it's at -5, the output would be at -12 dB. So, instead of the audio ranging across 15 dB in volume, it now only varies across 6 dB in volume. And as the peak is now at -12, you can bring your overall level up another 12 dB in gain without clipping.
Be careful, however—if there is a lot of background noise in your audio, and you apply too much compression, you'll notice the noise coming up and down in levels as well. This is referred to as “pumping”, and can be a noticeable distraction.
If you shot your video in a location like a gym, and you got an exceptionally clean recording through close mic'ing, you might find that it feels a bit “fake.” You might want to add in a little bit of reverb to make the recording sound more like a large room, but just a little—enough to add some realism, but not enough to make the speech harder to understand. Likewise, using a program like RX3 to remove all the background noise in an interview shot in, say, a factory, would make the factory background seem fake. Or perhaps you shot inside a room that looked out over a noisy scene, and that background noise wasn't audible in the room you were shooting. Record some audio of that background noise later so you can mix a little of it in to add some realism.
With a little practice and some attention to detail, your videos can go up significantly in quality by paying attention to the audio side of your video shoot and post-production work.
