Setting Up Your Recording Space and Dampening Surfaces:
The goal in ADR is to get a very clean recording of the new dialogue, with as little reverb and as little ambient noise as possible. Reverb is how noise sounds in a confined space as it reflects off walls and objects. Ambient noise is background (or “wild”) noise like fans, air conditioners, refrigerators, etc. The reason why you need to record audio as clean and reverb/ambience-free as possible, is so that you can introduce ambient noise and reverb you want after the fact.
Select a room that’s large enough for proper mic positioning (more on that in ‘Mic Positioning’) and which will allow your actor to face the larger portion of the room as he speaks. Make sure that he’s not too near walls on the side or behind him. (3’ to 4’ is a good distance to keep the side and back walls from the speaker.) The actor will need a lectern or music stand on which to have his lines (more on that in ‘Looping’).
Now that the actor’s location has been placed, it’s time to dampen all reverb as much as possible. There are complicated books on the subject of acoustic tiling and dampening that I’m not going to pretend to understand on this subject, so I will give you a very simplified, very visual concept of what sound dampening is. Think of sound like a bouncy ball. Just as hard surfaces release the kinetic energy of the bouncy ball when it’s thrown against one, which causes the ball to bounce higher, so hard surfaces cause audio reverberations to bounce back to the mic. When you put foam and dense blankets over hard surfaces, these dampening materials help “catch”—or absorb the “kinetic energy” of—the sound and prevent it from bouncing back.
With that said, you want to hang blankets and foam around the recording area to try and deaden the sound as much as possible. Also, hang a thick towel over the top of your music stand/lectern, as these stands have at least one part that consists of a large, hard surface.
Before you record anything in this room, make sure that every object that makes noise in the room is either turned off or covered with some sort of absorbent material. The most common “invisible” noises that corrupt ADR are ceiling fans, air conditioners, refrigerator compressors, ticking clocks, computer fans, kids playing outdoors, and the like. Obviously, you’re going to have a computer somewhere connected to the mic you’ll be recording with, so try to cover as much of it as you can with foam, blankets, and other sound dampeners. Also, have your actor completely turn off his cell phone—not just turn it to vibrate. Even on vibrate, cell phones emit interference when receiving calls that is audible to most audio recording equipment.
Choosing Your Equipment & Software:
You will need a computer that has a software package that will allow you to play sections of audio in loops and record audio on a separate track. While expensive studio software like ProTools and Nuendo provide a number of ways for you to do this, you can actually find this very useful feature in Sony's Vegas. Other editors like Adobe Premiere Pro can perform this function, though their looping and recording ability isn’t quite as good as Vegas’ due to the fact that Vegas started out as an audio program. Of course, if you’re going to be audio looping, programs like Sony’s SoundForge and Adobe Audition will allow you to play and record loops of audio for this purpose.
Next you will need the mic you recorded most of your dialogue on your film with. Hopefully this will be a shotgun microphone of some sort—unless you used lavaliers, which are good, too. Whatever mic you used for the primary recording of your feature, you should continue to use for the redubbing process, if possible. You will also need a mic stand that can be adjusted to accommodate your actors. (We'll cover more of that later.)
Now, you need to get the mic connected into your computer. There are a couple of ways to do this, depending on if the mic you wish to use requires additional power to run. If a mic requires additional power, it is referred to as requiring "phantom power". If the mic is phantom powered, PreSonus' Inspire 1394 is a preamp that will provide phantom power for up to two mics and convert the signal generated using your computer's FireWire port for $229. If the mic is not phantom powered, SoundTech has recently released an XLR-to-USB cable called the Lightsnake USBXLR10 for $69.99. While we haven’t reviewed it yet, it sounds very promising for home ADR studios, as many shotgun mics at least have the option of being powered by AA batteries, instead of phantom power.
Now we’re to the point where the choice of visual or audio looping comes in. If you are using visual looping, most video editors will let you kick out a video feed to an external monitor, but, like I mentioned before, your computer does need to have either multiple video cards or a multi-head video card to do this. If you have that, you will obviously need a monitor or television with the necessary length of cable to reach your actor. Finally, for both forms of looping, you will need a good quality set of headphones for both you and your actor, a headphone splitter, and enough length of audio extension cord to reach your actor comfortably. Sony’s excellent Pro MDR-7506 studio headphones run about a hundred bucks a piece and would be a very good investment. If you can’t swing that, then Sony’s MDR-7502 Pro Stereo Headphones run about half that and still give you pretty good sound.
To see how to set this process up in an editing program, read this article from a few issues ago which shows you the process in Vegas. Even if you’re not a Vegas user, this will give you the basic idea of how to set up the editing program of your choice.