Mixing Part II: Real Time Plug-ins & Audiosuite Plug-ins
Volume level setting isn't always the only factor is creating a good mix, there are other things that need may adjusting like EQ, reverb, and processing. This section is just an overview; it's not going to be a detailed exploration of all these possibilities, largely because different Pro Tools systems vary widely in their processing capabilities.
For instance, the Audiomedia III set-ups have limited processing because they are "non-TDM" systems. "TDM" is a Digidesign term for "time division multiplexing" -- which isn't especially enlightening, is it? Let's just say that this TDM business requires dedicated Digital Sound Processing (DSP) chips that are on the higher-end Digidesign PCI cards. Without those cards, you have limited capabilities, especially in terms of "real time" effects.
However, Digidesign has just introduced a new form of real time plug-in, called RTAS for "Real Time AudioSuite." These use the processing power of the Mac CPU itself, which on the higher end machines will allow you to run a small number of real-time plug ins during a session (results vary depending on how complex the plug-in is.)
Most of these plug-ins are made by third-party companies as optional software add-ons designed to work with Pro Tools. So not all systems will have the same plug-ins installed.
Now -- what is this distinction about "real time" all about? Real time plug-ins work very much like having a piece of "black box" hardware plugged into a track. You push a button called an "insert," and select from a list of plug-ins. Suppose you pick one that adds reverb. You play the track and fiddle with the reverb settings until you're happy, then you can go about more editing and mixing. If you change your mind about the amount of reverb, you simply alter the setting.
But many of these plug-ins have non-real time "Audiosuite" versions that are accessed from their own menu. These Audiosuite plug-ins work by actually making a new "processed" copy of a region you select and replacing the original region with the processed version. (There's a "preview" function that gives you an idea of what the new soundfile might sound like.)
Since the Audiosuite process actually creates a new soundfile, changing your mind requres deleting the new file and going back to the original to try again. One advantage of Audiosuite plug-ins is this: once a file is processed, you're not dependent on the plug-in to achieve the effect; the effect is "built into" the sound.
Instead, suppose you had set up some perfect TDM-style reverb using the Brand X plug-in on a particular Pro Tools system. If you took that session and opened it up on a system that didn't have the Brand X plug-in, you'd be out of luck. You couldn't recreate the reverb. With a file processed via Audiosuite, that sound would already be reverbed to your taste.
The whole "plug-in" concept allows for a lot of flexibility and innovation. Since these plug-ins are software rather than hardware, they're constantly evolving -- which is another reason not to go into too much detail on how to use them, since a new version will be along any minute. You'll find Audiosuite versions of some interesting plug-ins on the Pro Tools LE systems. Likewise some really great RTAS toys. The better ones tend to have a fairly intuitive interface so the best thing to do is experiment -- just plug away.
Real Time Processing Via Insert Plug-ins
Let's look at a very simple example. (Lots of complex plug-ins may be available on the system you're working on.)
The most common "tweak" of your mix will probably involve EQ. You might want to add a little more bass to one sound effect, remove a bit of hiss from another, remove some wind rumble from a voice, or make it sound like it's coming through a cheap speaker. You can do all that with the EQ available in Pro Tools.
The easiest approach is to use the "real time" versions. These are available through what are called the "inserts" of each track.
[In the Audiomedia III systems, these inserts only access software. In systems with a more elaborate audio interface, hardware channels can also be accessed through the inserts buttons. Also, on the Pro Tools 24 systems, the TDM plug-ins are accessed through the inserts.]
You can view the inserts from the Edit Window or the Mix Window. Since the inserts would hog a bit of "waveform space" in the Edit Window, we'll access them from the Mix Window. To do so, we choose Display|Mix Window Shows|Inserts View.
Looking at our Mix Window, we should see a new set of buttons at the top of the window. (Your system will probably have five inserts -- the system shown here has only two inserts per channel, and just a few plug-ins.)
Clicking on one of the inserts buttons
will bring up a pop-up menu; this one has choices of high
pass, high shelf, peak notch, low shelf, and low pass.
These are choices for various forms of
EQ. Choosing to use one of these EQ inserts
on track 1 means that all the sound regions on that track
will get this EQ treatment (just as if we were adjusting the
EQ knobs for track 1 on an analog mix panel.)
The Insert EQs
Here's a very brief look at these EQ windows and a few examples of how they might be used.
The High Pass option allows all
frequencies above the selected frequency to "pass through."
(Since the purpose is to eliminate lower frequencies, these
are sometimes called "low cuts.") The frequency is selected
by moving the slider. 75 Hz is a rather low frequency; you
might use a setting like this to reduce wind rumble in a
recording made outdoors. Raising the frequency pass thru point
higher could result in a much "thinner" quality. With voice
recordings this might help simulate a telephone
effect.
High Shelving
"Shelving" EQ can be thought of like the
typical bass and treble controls found on consumer audio.
High Shelving is like a treble control. We can boost or
lower high frequencies by using the "gain" slider. One
difference from most consumer gear, though: with this window
we can choose the frequency at which the gain or boost
begins. This particular setting might be used to reduce hi
frequency tape hiss.
Peak Notch
This is a "peak/notch" type of EQ. (This
style is often called "parametric.") Here we can click some
icons and select the width of frequencies we're affecting,
from just a narrow "skinny" range to a wider "fatter" range.
We can select the parameter of the frequency located in the
center of that range. Then we select whether to reduce or
increase the level of those frequencies. In this example we
are reducing a fairly narrow band of frequencies around the
60 Hz range. You might use this setting to reduce certain
types of electrical hums.
Low Shelving
"Low Shelf" -- this is like the common
consumer "bass" knob. Again, we can use the frequency slider
to change the point at which the boost or reduction
occurs. You might use this setting just to bring
up the bass response of some music.
Low Pass
A "Low Pass" lets low frequencies pass
through unaffected. (Or you can think of it as a High Cut,
since it's used to "cut off" high frequencies.) 15 KHz is getting toward the upper scale
of human hearing -- "dog whistle" territory. You might use
this setting to eliminate a high pitched whine from a
recording -- the kind of subtle whine that television tubes
sometimes give off.
You can use more than one insert per channel and combine the effects of these EQs. For instance, combining a high pass with a low pass, so that only a fairly narrow range of middle frequencies passes through can create the effect of a very cheesy loudspeaker.
One point to be aware of: when you boost frequencies, you boost overall level. Make sure that your EQ setting doesn't create levels that will cause digital clipping on your track meters.
There's a whole menu of choices under the Pro Tools "Audiosuite" menu choice. Contents may vary, but you might see something like this:
A number of these, especially the "D-FX"
sets, are optional items. The standard Audiosuites are:
Invert, Duplicate, the EQs, Normalize, Gain, Reverse, DC
Offset Removal, Time Compression/Expansion, and Pitch
Shift. A few are unlikely to be used by most
students. "Invert" will flip the phase of a soundfile by 180
degrees -- useful if you have a stereo recording with phase
problems; not much use otherwise. "Duplicate" will create a
new soundfile that is a copy of a region or portion of a
region. "DC Offset Removal" will eliminate an obscure and
rather rare problem with some digital files. The "Normalize" and "Gain" plug-ins allow
you to increase the gain of low-level soundfiles. The EQs available give you somewhat more
choices than the insert EQs -- for instance, the 4-Band EQ
gives you two shelving bands and two Notch/peak bands that
you can use simultaneously. Of perhaps more interest are items like
Reverse, Time Compression/Expansion, and Pitch
Shift.
We'll look at only couple of these, but there are features common to
all that we should be aware of.
If we highlight a region, or a portion of a region, and select "Reverse" from the menu, the following window comes up. Let's look at the default settings:
The name of the plug-in -- "Reverse"
appears in the upper left. (Clicking on the plug-in name
will bring up the list of available plug-ins -- just another
way to access them.) To the right, "Playlist" indicates that
our selections are made in the track display area of the
Edit Window (rather than the Region List.)
The next item -- "use in playlist" -- is highlighted to make it
active. That means that whatever new soundfile we create will
automatically appear at the same place and in the same track as the
region we've selected, replacing the old selection. (Otherwise the
new file will just appear over in the regions list, as if it was
imported into the session, and we could then drag it into a track.)
The next item "create individual files" is especially important. This means that the original soundfiles stay intact, while additional new processed files are created. Some of these plug-ins will give you the option of destructively overwriting the original files. This would usually be a bad idea, since overwriting cannot be undone.
"Region by region" means that if you've selected, say, three separate regions to process, then three separate new files will be created. (Or you can choose to create one larger file.)
Clicking on preview lets you hear what the processed file should sound like. (If you've made a very large selection, only a portion of it may play in the preview mode.)
Clicking on "process" will create the new file. It will appear in the Edit Window track, and it will get a default name based on the Track Name and the processing done. For instance, reversing a region found in Audio 2 will produce a new file called "Audio 2-RVRS-00-00." (Usually you'd want to rename these files.) In any case, this new reversed file will sound like a backwards version of our original region.
Next, here's the window for "Pitch Shift":
<---- There are a few more buttons
overall because there are more parameters to the processing
itself, but it's essentially the same kind of window. In
this case, by dragging the "coarse" and "fine" sliders, we
can control the amount of pitch shifting that takes place.
(You can think of pitch shifting as playing a higher or
lower note on a keyboard -- you produce essentially the same
kind of sound, but at a different pitch.) Note also two new buttons common to some
of these plug-ins: the "bypass" button next to the "preview"
button allows you to momentarily bypass the preview mode,
giving you an easy "before" and "after" audition. The
"compare" button is automatically highlighted whenever you
adjust a parameter; it can give you a visual "before" and
"after" of your settings. "Factory default" in some cases allows
you to pull up a menu of pre-set process settings. There
aren't any for Pitch Shift, yet there are a number of
interesting pre-sets for plug-ins like Lo-Fi, Sci-Fi, and
others. The button just to the left of "Factory
Default" brings up a dialog that allows you to save some of
your own custom settings.
Most of these interfaces are fairly intuitive; especially after
you've used one or two, the others will seem like "variations on a
theme." Time permitting, you may want to take a few sounds of your
own and just experiment with likely-looking plug-in. Just make
sure that you are not destructively overwriting your original
soundfiles.
Go to Bouncing, Consolidating, and Duplicating Sounds
Copyright ©2000 by Rodger Pardee