In just three short blogs we’ve come a long way in improving the audio quality of our YouTube videos. This final installment in the series will cover three important topics that have not been discussed yet: Headroom, Level Consistency, and Limiting.
Headroom? What could my ceiling possibly have to do with this?
I’m referring to the headroom of your recording levels. As we saw in the second blog, once your microphone input is set on your DAW, you can see the audio level, or the “gain,” on the meter. The higher your gain setting, the closer to the top the meter will read.
Where we run into problems is when the gain crosses 0dB on the meter. If you were to look at the audio wave of a signal driven past 0dB, the peaks of the wave would be cut off. This creates a distorted, choppy kind of sound known as “clipping.” In the world of analogue audio equipment, some of this distortion can actually sound pleasant, adding some grit and warmth to the audio. If you are using digital equipment, which this guide assumes you are, then clipping will never sound good and should be avoided at all costs.
In order to ensure that you don’t clip while recording audio, it is a common practice to set your recording level so that the audio peaks around -12dB. This way there is a 12dB buffer separating your audio from clipping, giving it some room to play in case the audio source gets louder or has effects applied to it later that increase the gain. There is no need whatsoever to push your audio close to 0dB when recording. Doing so will only make your audio more likely to clip. Always record at conservative levels, then raise the gain to an average listening level later — more on that in the Limiting section below.
Level consistency? So all of my meters should be at the same level?
Not quite — Level consistency is about checking each piece of audio to make sure that its volume flows smoothly relative to the other pieces of audio. Naturally, some audio clips in your video are bound to be louder or quieter than others, like soft background music or loud sound effects. The key is to make sure that nothing sticks out as being too loud or too quiet, especially if you are recording multiple shots of one scene that is meant to have a consistent volume throughout.
As you can see in the image above, I have three different clips of audio in the timeline of my video editing software, in this case Adobe Premiere. The brighter colored segments depict the audio’s waveform (if the clip was recorded in stereo, then there are two waveforms, the left and right channels). The gray horizontal line across each clip represents its volume level in the mix.
The clip on the left was recorded at a much lower level than the green clip on the right. In order to balance these two clips in the mix, the clip on the left has its volume boosted, and the clip on the right has its volume drastically reduced. This may seem very simple, but it can be tricky when you have a lot of different audio clips that need to be adjusted by small amounts in order to flow smoothly.
As I mentioned in the previous blog on EQ, do not make your audio decisions based on what you see — make them based on what you hear. It helps to close your eyes and listen through your video as it plays back. When something jumps out at you, adjust the volume, then play the video back again until all of the clips are balanced relative to each other throughout the whole video.
Limiting? But I’m a creator! There are no limits on my creativity!
Well unless you put limits on your audio your work will suffer. If you remember from the section on recording levels, your audio clips were recorded at a conservative level (-12dB) to prevent running into clipping problems. This is much quieter than commercial releases for audio and video media, which have their gain boosted close to 0dB (technically they use a different volume measurement like LUFS, but for the sake of learning let’s stick with decibels).
If the media I listen to is boosted to 0dB how does it not clip?
That’s where limiters come in! A limiter is a tool that will clamp down on the gain of a piece of audio once it passes a certain threshold.
The threshold of a limiter is often called a “ceiling.” The Out Ceiling knob at the bottom of the picture above shows that the threshold is set at -1dB. The meter on the left shows the audio passing into the limiter, and the meter on the right shows the audio after being processed through the limiter. You’ll see that the meter on the left is clipping, but the meter on the right is pushed up against the ceiling set at -1dB. Thanks to the limiter, the audio we hear will not go past the ceiling into clipping territory.
A common practice is to set the ceiling of your limiter to -0.3dB so that you squeeze as much volume as you can out of your audio with a bit of wiggle room left over. This is important if you convert your audio to mp3, which can boost the level a tiny bit. A threshold of -0.3dB ensures that your audio won’t clip no matter what.
Great, so is that all I need to know about audio production for YouTube videos?
There’s a heck of a lot more out there to learn, but these four short blogs have given you the most important tools to transform your audio. Anything else is really just icing on the cake.
Now go forth and make videos with the audio quality they deserve. Huzzah!