When most video editors hear the word “compression,” they might think about getting the video file to the smallest size possible. In audio terms, it means that you are using more of the sound range. In this movie, authors Richard Harrington and Cheryl Ottenritter explain what compression means and how to compress audio in Adobe Premiere Pro.
- Cheryl, what's the goal with compression? Most video editors, when they hear compression, think about getting the file down to the smallest size possible for delivery, but we're talking about audio here. - Right, compression here means the dynamic range compression. Meaning from, how to compress the lowest of the low volume, and the highest of the high volume. So when you compress you're really bringing up the lows and tightening up the highs. So you're compressing, think about it as the compression of the sound.
And then that way if you're bringing down the highs, you can actually bring everything up a little bit. - So the low sounds, the quiet moments aren't quite as quiet, and the highs don't spike as much. So it's in a way, it's what many people think of as normalizing the volume, but it's both the lows and the highs and you're making sure that you're using more of the sounds range. So that the person isn't cranking up the volume on their speakers and then all of a sudden it blasts them? - Right, exactly, it limits the really, the big range so, and it keeps on getting it tighter.
As you get it tighter and tighter and tighter and tighter and tighter, until almost you're limiting. - I've noticed that with commercials, for example, that they overdo it on commercials so everything sounds loud and it cuts through. - Yeah, I'm to blame for that. - Alright, it's her fault. - It's all my fault. - Let's look at a sequence here and we'll apply some basics of compression, and then we'll revisit this here for specific individuals. But why don't we take a look at this? Should we do it maybe globally to the master or do you want to play it on a clip, what would you do? - [Cheryl] Well, can apply it on a clip but you're going to have more limitations that way because you'd have to apply it exactly to all the clips just like you did the EQ, but it even harder with compression.
So I would say let's go ahead and put it on the track. - [Richard] Which track should we use? - [Cheryl] We could use another dialogue track, that's fine. - [Richard] Alright, so, I'll solo this so it's a little bit easier to hear, just that track. Let's just close the VU meter for just a second. And we'll come down here to Dialogue 2 and solo that. And at the top here, we just need to make sure we're seeing the controls and so, let me make sure I got the right one, there it is and we'll open that up and we're looking for compression and so which one are we going to use? - [Cheryl] We're going to use the one called Dynamics.
- [Richard] Okay, and so this actually does a lot of different things, but compression is one part of it. - [Cheryl] Right. This is a very, very unique tool, in that it gives you different ways to control the dynamic range of your sound. We're going to focus on the Compressor right here. It comes up with the Compressor checked and the Auto Compress checked. I'd immediately take the Auto off. - [Richard] You mean Auto's not as good as if somebody thinking for themselves? - [Cheryl] Exactly. - [Richard] Alright. - [Cheryl] And so one thing that it will do if we go ahead and put it in and then out.
Looping is your friend when you're mixing. Make sure you're on Loop. (plays man speaking) - [Cheryl] You can loop this and before I actually listen to what I'm doing I want to show you what's happening. This is a nice tool, in that, it will actually show you how much you're compressing the sound. - [Richard] Okay. - [Cheryl] So let's go ahead and bring down the threshold. You can see that it's compressing. Almost to the point where it's muting it. - [Richard] Right. - [Cheryl] You don't ever want to see that much on this Compressor on this tool.
Most compressors... You only want to compress between two and six or zero and 60B. Most compressors can't even handle 60B. Of compression, so this is a visual tool to help you know where you've gone too far. - [Richard] Okay. - [Cheryl] So we're going to get into this more but this is the threshold. This is the threshold of when the compressor is actually going to kick in. - [Richard] And that's on the loudness side, the high end side? - [Cheryl] Right.
So a good safe place is 20 but we'll talk about that more. Ratio is how much it compresses. - [Richard] It's more aggressive? - [Cheryl] How aggressive, one is nothing. No compression will happen. No matter where you set your threshold. Two is a good compressing to start with. But you can see... That four to one. By the time you get up to eight one or 10 to one, you're really limiting. There's no actual breathing room there at all.
- [Richard] So somewhere between one and two is most common? - [Cheryl] I would say between two and four. One to two is barely, barely to clean the compressor. I usually start with two. Attack, depending on what you're doing, a quick Attack is nice. - [Richard] And that means how quickly it latches on and engages the compressor? - [Cheryl] Exactly. Release is the opposite. How quickly it will release. Depending on what you're doing, you'll want either a long or a shorter release.
For a voice, it's mid-range. - [Richard] Okay. And you would use short on something like music? - [Cheryl] Um, I actually use longer for music because it's so long and you prevent... Because it's so long. And also I use longer for the actual mix itself. - [Richard] Okay. So if you're applying it to the master track? - [Cheryl] Right. - [Richard] Okay. - [Cheryl] If you're applying it to the master track. MakeUp gain is how much MakeUp you want to gain, because remember when you're compressing, you're bringing it down some. So it allows you to actually have more volume, more punch. (plays man speaking) And that's how a compressor works.
- [Richard] Alright, so to break this down, my understanding here, I'll pause this, is that Threshold is affecting how much we're going after. And this is going to be, not a direct relationship but you're going to have to dial this in subjectively, based upon what you're listening to. - [Cheryl] Yes, Threshold is the level in which it engages. - [Richard] Okay. - [Cheryl] The point in which it engages. - [Richard] Alright, and our Ratio is going to affect how often it engages? - [Cheryl] How much. - [Richard] How much, okay. And then Attack is going to say when does it get triggered and Release is when does it stop applying? - [Cheryl] Correct.
- [Richard] So, depending upon the subject, this is how frequently it engages and how smoothly it transitions out. And because were lowering things down, we need to use MakeUp to bring everything back up. So essentially, if you don't add MakeUp, you're going to be lowering everything, or pushing it down. And then this brings everything back up but it means that everything got louder, but the higher end stuff got limited and pulled back down. So this is a lot like a limiter in a way as well. - [Cheryl] Right. A compressor is a limiter but, laid back.
I always call a limiter, a compressor on steroids. - [Richard] Okay, so this is a more gentle way to do it that just creates a more even mix and keeps your volumes more consistent. Alright, I think we got a pretty good overview on how EQs and compressors work. The basic mechanics. Why don't we move on and take a look at some specific scenarios and apply these in a real world situation.
- Setting up your tracks in Premiere Pro
- Organizing tracks on the Timeline
- Adjusting audio levels on the Timeline
- Switching between track and clip control
- Using the Clip Mixer and Track Mixer
- Using submixes for routing and stem mixing
- Adding clip-level effects to audio clips
- EQ for male and female voices
- Removing background noise
- Compressing the master track