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In this course, professional audio engineer Scott Hirsch shows how to create an evocative sound mix for a film or video, built from basic audio collected during the shoot and transformed into a final mix using Pro Tools 9. This course shows how to set up and optimize a Pro Tools session template for projects with unique requirements, record Foley and ADR audio, layer sound effects, perform corrections such as noise reduction and pitch shifting, mix for stereo and 5.1 surround sound, and finally, how to format and deliver the finalized mix, whether destined for DVD, movie theater, broadcast, or the web.
Playing music underneath a spoken voice is a very common practice in documentary and other types of video. In this movie we will explore a technique called ducking that can help the voice to always be heard above the level of music. Here in this session we have a dialog track and music track to play under it. Let's take a listen. (Music playing, speaker inaudible) So obviously here the music is way too loud and this is a common scenario when you bring in any arty mastered music into your audio over video session.
The music is going to be typically too loud. So we are going to have to pull that down and we'll just take a listen and we will roughly get the volume level of the music into the ballpark. (Music playing, speaker inaudible) That seems about a good spot for the music. It's about -13 and let's hear a little later in the track when the music kicks in a little more. (Music playing, speaker inaudible) So here the music's got some more drums and bass and at that point it's still kind of sitting in the right place, but you can hear it gets in the way of the dialog a little bit.
One technique we can obviously use to control this would be too automate it down a little bit there, which we may end up doing. But also I want to show you this technique called ducking which actually uses a compressor plug-in on the music track and that compressor plug-in is going to get triggered by not the music track itself like a normal compressor, but from an external track. So in other words the dialog track will be triggering the compressor on the music track. Let's see how we can set this up. We are going to Music > multichannel plug-in > Dynamics and we will use Compressor/Limiter Dyn 3 plug-in.
So this plug-in like a lot of compressor plug-ins has a special area over here called Side-Chain and when you use the Side-Chain it means that you use something called a key input. So, to activate this, first we want to select and activate the little key where it says Side-Chain which means that the compressor is now listening externally for a key input, and the threshold is not going to be activated by the music on this track, but rather another track, in this case the dialog track that we send over the key input.
We do that via an internal Pro Tools bus. So let's go over to the dialog track here and I will go to the mix window. So on this track we are going to go in and activate a send and on the first send slot, we will send this on Bus 1 and we want to Option+Click on the send fader to get that to unity. So now we are sending the dialog track over this bus and we are going to return that bus back into the compressor. So where it says key input here, that little key icon, we are going to set that to Bus 1.
So we are sending over the dialog track into this compressor. On a normal compressor the levels of the track itself that the compressor is inserted on reach the threshold and therefore activate that compressor to reduce the volume of the track. In this case it's not going to be the music itself, but the key input, the dialog. So in other words whenever the dialog is spoken it's going to activate the threshold of this plug-in and therefore the compressor will act on the music. So we are going to be ducking the music whenever the dialog occurs.
So we have are key input set up over Bus 1. We've activated the key button over here in the Side-Chain. Now we just need to set the controls of the plug-in so that they activate correctly so they don't compress too hard or too little. So one thing we are going got definitely want to do is turn up the Ratio. We don't want to get into a situation where we are limiting it too hard. The limiter would be up here about 100:1 ratio, but we are not going to be too light with it either. We are going to probably around 25 to 1, which is a pretty hard compression, but again we do want to duck the music when the voice happens.
So we will set it somewhere around there. We can actually also turn up the Knee, which in this plug-in kind of reduces the compression artifacts. Again, we want the compressor here to be somewhat transparent. We don't want to be hearing the music compression. We just want to feel it a little bit to reduce down when the dialog happens. So maybe soften the Knee a little bit it should help us to have less artifacting. For the Attack and Release, those are our time-based controls. So the Attack should be fairly quickly. We want to grab onto the audio as soon as the dialog hits the threshold. We want to grab onto the music pretty fast and start compressing right away.
And Release we will be a little more gentle with. We are going to let it go a little slower. So it lets go of the gain reduction in a slightly slower way. Then the last most important setting is our Threshold. So if the Threshold is too high up here, then it won't hit the threshold as it comes in over the key input and we won't hear any compression at all. If the Threshold is too low it's going to activate too much and we are going to hear it all the time. But for demonstration purposes I am going to start out really, really low on the Threshold. So it will be really hitting the compressor hard and we will back it up from there.
So let's take a listen to what this is going to sound like. Keep in mind on the meters here, gain reduction is the amount of compression. So if we set everything up right you should hear gain reduction here coming from the top down only when we hear the dialog. That means again that the dialog is actively controlling this compressor. Input and output are going to be the level of the music. So the input is how the music comes into the compressor and the output is how the level of the music coming out. So if we are doing our job correctly, when the dialog is spoken the meter on the Out should be a little less than a meter on the In.
But of course, we are going to just use our ears mostly just to determine if it's working or not. So here I am going to play the music and we will listen and right now the Threshold is really low. So it's going to be a very obvious use of this technique and we will back it off from there. (Male speaker: And in that year we met a woman named Barbara Scott from San Francisco who did a workshop in Santa Paula.) (Male speaker: Right just down the?) So here since the threshold is so low it's actively compressing the music so much that we can barely hear it. But if you notice right there in that section the actor stops speaking and the music just poked right back through.
So again it's really working that when he's talking the compression's happening and when he stops talking the music creeps back in. Let's take a listen to section one more time. You can hear what I am talking about. (Male speaker: Stuff started making sense for us.) Now just in that little instant when he stops talking the music creeps back in. So doing what we need to do, we just need to back off the Threshold little bit so becomes a little less intense. (Male speaker: Stuff started making sense for us.) (Music playing softly) (Male speaker: So we formed a group and at first there were very few of us.) (Male speaker: But over time we began to learn things and we began to?) So that's more kind of in the ballpark of where we want it.
I mean, we are still hearing the compression act pretty hard on the music. So in that case if you're hearing that we want to refine or Attack and Release and kind of refine our Threshold a little bit. Now I am going to listen one more time and just try to get it. So it's a little more subtle. (Male speaker: In Santa Paula right just down the street here.) (Music playing) (Male speaker: And suddenly a lot of this tuff started making sense for us.) (Male speaker: So we formed a group and at first there were very few of us.) (Male speaker: We didn't know what we?) So around there it's starting to work for me. It's not totally obvious in terms of us hearing the music duck drastically, but it's just carving out a little to space underneath every word that he speaks.
Then if we wanted to really go in here and do this the right way, we would go in and automate the volume as well. So we are getting the benefits of our ducking plug-in plus any automation we would do. And this is how a lot of engineers do it. They will use this ducking technique along with volume automation, just enough to make the music get out of the way of the voice so it doesn't get lost on any type of listening system. Remember, you don't know what type of listening system this might be heard on. If it's a laptop, you got a lot smaller speakers to deal with. If it's a TV. So you just want to make sure that the voice is heard in all cases and the music is still present, but this technique allows us to really make sure it's out of the way.
It also can be a real timesaver. If you're working on a lot of commercial spots and you don't have time to really go in and detail your automation moves, you can use this ducking technique in even a more dramatic way than we are using here just to quickly duck the music out of the way of the voice that it can always be heard.
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