MIXING IN PRO TOOLS - PART I : LEVEL ADJUSTMENT
Back when we first opened the Pro Tools Demo Session, we experimented with adjusting the track playback levels by using the virtual faders in the Mix Window. This is really the easiest way to do basic mixing in Pro Tools, especially when you're dealing with just a handful of regions spread across a small number of tracks.
The default setting for the faders is "0", indicating "unity gain" -- which is another way of saying "no change" or normal level. Dragging the faders downward gives you various "minus" increments indicated in decibals. Fully closed faders are considered to be at "minus infinity." You can also push the faders up to boost levels up to a limit of +6 dB. [Hint: To reset a fader to "0" Option-Click on the vol bars or faders.]
This approach follows the model, or paradigm, of analog mixing from multi-track. It's especially simple if we have enough tracks so that each separate sound can be on its own track. This makes mixing easier; we can adjust the track level so it's just right for the sound playing on that track. Then, since there's no other sound on that track that we need to worry about, we can just move on to the next track adjustment. Once we get each track level set we should be able to sit back and play the whole session from beginning to end without any adjustments. (The slang for this is approach is "set and forget.")
Let's look at a simple example of how this works. Here we have a session with three different sounds.
We could fit our two "biplane bys" onto a single track, but in this case we want the 1st plane by to play much lower, as if it is more distant, so we place the two sound regions on different tracks. We adjust the level of Audio track 2 by clicking on the "vol" bar and dragging it downwards so that its about 12 dB lower than normal. (We could do this in the Mix window if we preferred.) We might continue spreading our regions across tracks and adjusting our track levels in this way. Eventually we might run out of Pro Tools tracks because there is a limit to how many simultaneous tracks the system can play back, but with simple sessions we could put each sound on its own track.
In most film mixing, though, we usually have a lot more material than we have tracks, and each track could end up holding a wide variety of sounds. Since it's unlikely that a "Distant Cat Meow" that first occurs on track 1 is going to play at the same level as the "Atomic Explosion" that follows it, this means level adjustments will have to be made during playback.
So one of the skills in good sound editing is to organize the material on the available tracks, spreading it out in such a way that it's easier to mix. The ideal might be a "set and forget" scenario; in reality we have to come up with a good compromise. So if we have 16 sounds and 8 available tracks, it's probably not a good idea to put all those sounds on just one or two tracks. If we arrange them around on the available tracks they should be easier to mix. There are some general rules to follow:
To illustrate, suppose we have a scene where our villain fires a gun three times in quick succession. If these three events happen in the same close-up, we could put our three gunshots in the same track, since no level adjustments should be needed. But suppose he fires twice in a wide shot, and the third time in a close-up. In that case the first two gunshots could be on the same track, but the third should be on a separate track.
Any time you are going to do traditional analog mixing -- either directly out of Pro Tools or by first doing laybacks to another medium -- you need to pay attention to these layout principles. There's much more involved than in the simple example above, but we're not going to discuss it here. That's because, if you're mixing directly in Pro Tools, you're entering a whole new paradigm with its own set of rules.
Many simple projects can be mixed as described above, just by placing a single region in each track (or similar-sounding regions in the same track), setting the track levels to taste, and playing the whole session while recording the mix onto a tape deck. In some cases, you may need to make a few adjustments to the "virtual faders" during playback. In those situations, you're basically doing a "live" mix, in real time.
That's the simplest way to work if you have only a few sound regions in a session. But as our sessions get more complicated, sooner or later we'll run up against track number or voice limitations.
[The LE systems can, in theory, run a maximum of 24 tracks, but this depends a lot on factors like CPU and drive speeds, etc. "Actual results may vary." The TDM systems can run 32 simultaneous tracks, but more virtual tracks can be created. Remember that "voices" refer to the maximum number of simultaneous sounds that can be played on the TDM systems. When we create 32 tracks, they are assigned voices 1-32.
But if we create 40 tracks on an 32 voice system, tracks 33-40 are assigned to voices 1-8 as well. This creates a possible conflict. If two regions assigned to the same voice are supposed to play at the same point in the timeline, the "top" track takes precedence, and only it will be heard. Example: if we have a dog bark on track 1 and a tire skid on track 33, they are both "voice 1." If they occur at totally different times, there's no conflict. But if they both occur at the same time, only the dog bark will play.
Why bother with creating more than 32 tracks if it can create conflicts? Often we can spread the sounds around in a way that will avoid conflicts. As long as there are brief gaps between the end of one sound and the beginning of another so that they don't overlap, there's no voice conflict.]
At some point we won't be able to easily put each region on its own track.
But even when we have tracks that are chock-full of different sounds, we can use the automation features of Pro Tools and still achieve a "set and forget" result. The simplest approach to automation is to experiment with "volume stamping" a region. Suppose that in our earlier biplane example, both regions were placed in Audio track 3:
If we click on the button in the Track
Strip that ordinarily says "Waveform", we'll see a choice of
alternate display modes. Right now we're interested in
volume, but first -- just to get it out of the way -- let's
take a quick look at the "blocks" option.
The "Blocks" display is sometimes chosen
after all the serious editing is done; it makes it easier to
read the "big picture" of the session, and on slower Macs it
requires less processing of waveform re-draws.
Leaving that aside, lets look at this other pull-down menu choice of
"volume." Selecting "volume" gives us this Volume Graph
display:
The waveforms take on a less distinct
look because we want to focus on volume information. The
horizontal line represents the volume graph of the track;
right now the line corresponds to it's normal level of "0".
Notice how it's at the same height for the entire length of
the track.
In the above case, the small vertical line in the middle of the first "biplane by" is the Smart Tool operating in the Selector mode. When we're viewing volume graph data, the Smart Tool behaves a little differently, which lets us use an important new feature of the Trimmer.
By raising the Smart Tool toward the top
of the region, it converts into a new Trimmer Icon. The
Trimmer has a unique function when we're in the Volume Graph
display mode. By dragging it up or down, we "stamp" the
region with a new volume level that is reflected by the line
of volume graph data.
<---- Here we've dragged the
volume down, lowering it by 16 dB. The light gray line below
the trimmer represents the "target" level, and the number
display above gives the details of how the level is being
adjusted.
Once we release the Trimmer/Smart Tool,
we can clearly see the result. Volume Graph "breakpoints"
have been created, volume stamping the region to play at a
specific level.
Now if we play the session, our first biplane region will play lower
than normal (-16 dB lower.) The second biplane will play at the
normal, or "0" level.
We can listen to the results and go back and make more adjustments by reapplying the Trimmer. Or we can adjust other regions in the same way, "stamping" each region with a level as appropriate.
If you prefer not to use the Smart Tool, you can always switch to the Trimmer simply by clicking on it. There's just one minor complication, one that makes the Smart Tool handier for this. You'll notice that our second Biplane By is actually made up of three contiguous regions. (The "fade in" and "fade out" are considered separate regions.) If you were to take the Trimmer and click on any one of those regions, only the level for that one region would get changed. But obviously you'd want to make the same level change to all three regions. You can easily do this with the Smart Tool working as a Selector.
First, place the Selector bar in the
middle region. --> Then double-click with the Selector. All
three regions should highlight. (Pro Tools recognizes the fades on either
side as "belonging" to the middle region.) Now you can just raise the Smart Tool
toward the top of the region to convert it to the Trimmer,
and you can raise the level for the 2nd Biplane
---> Here's the end result after you release
the Trimmer -- the 1st Biplane plays low and the 2nd Biplane
plays loud. ----->
Besides fade ins and fade outs, there are other times when you have a sound that has been cut up into several regions. Then you also need to use the Selector to highlight the entire area you want to volume graph. To Highlight more than one region, you hold down the Shift key while double-clicking the regions you want. (Or you can click and drag the Selector to highlight several regions as well.)
You can see that volume graphing is fairly easy to do; it's also easy to erase it and start over. To delete volume graphing, just click and drag the Selector Tool to highlight any number of breakpoints, then press the Delete key (or use the Cut or Clear edit commands.) When we're in the Volume Graph display mode, our actions only affect automation information, so we don't have to worry about deleting any actual audio regions. Only the volume graphing will change.
Changes in playback level done via volume stamping in this way are essentially instantaneous. One result is that, as long as we're doing our mix strictly in Pro Tools, the usual rules about leaving enough human reaction time between events is no longer important. With volume graphing, we can mix very complex sessions, even as we cram more events onto fewer tracks and voices. (As a practical matter, it's still a lot easier to keep the whole workflow organized if you spread it out in some coherent fashion.)
By the way, if you find yourself switching back and forth between waveform and volume graph displays a lot, there's a combo keystroke that's very handy. Simply click within one or more tracks, then press CONTR and the "MINUS" key. This lets you toggle back and forth between the two display modes. Note: the "MINUS" key has to be the one on the main alph-numeric keyboard (next to the Delete key), not the one on the numeric keypad.
Adjusting Automation with the Grabber
Like those TV infomercials say, "But wait! That's not all!" You can also create and adjust Volume Graph points by using the Grabber Tool. In the Volume Graph mode, the usual Grabber converts into a "finger pointing" Grabber. With it, click anywhere on the Volume Graph line. A new breakpoint is created. You can move these points around by clicking and dragging on them. In the example below, we first create two new breakpoints:
<---- The first breakpoint is outside
the region; the second one is inside.
<---- Click and drag the first
breakpoint to its lowest setting. (This is like starting
with a fader fully closed.)
<---- Releasing
the mouse, we see the result. Sound level will start off
silent, then increase up to normal. (This is another way to
do a sound fade in.)
There's yet another way to create a series of volume graph points. When viewing Volume Graph information in the track display, the Pencil Tool allows you to "draw" volume points by clicking and dragging the Pencil. Here's one done in the "Freehand" style. [You can change styles by clicking and holding down the Pencil Tool button to reveal a menu.]
There's still more you can do with Volume Graphing -- like copying and pasting Volume graph points onto other regions and so forth -- but that really covers the essence of it. It's a very selective, accurate way to make level adjustments.
There's also a slight "artificiality" to mixing in this way. After all, we're not actually listening to the sounds as we tweak and fine tune these volume breakpoints. First we "visualize" a volume change, then we listen to it, then we re-visualize it and re-adjust it.
Which brings us to another automation option --
This is basically like having the kind of "moving faders" that fancy automated mix boards use, only we use "virtual faders" that can only be moved one at a time with the mouse.
[There are a number of hardware interfaces on the market that provide real faders and knobs that will read and write information back and forth with Pro Tools. With these devices, more than one fader can be adjusted simultaneously.]
In the Edit Window's Channel Strips, you may have noticed a "Read" button to the right of the "Rec" button. This button enables automation features.You can do automated level adjustments in the Edit Window, but the virtual faders in the Mix Window will give us smoother control. So bring up the Mix Window by either choosing Windows|Show Mix, or by using the shortcut Splat-Equals Sign.
In this example we want to fade up a bit of stereo music that for some reason we've elected to put on two separate mono tracks rather than a single stereo track. These means that we'll need to group these two tracks together so that any level adjustments we make will affect both tracks.
Notice in the Mix Window that there's a little list of "Mix Groups." These are groups that already exist in this session. "All" is always an option; this would group all the session faders together. "Group 1" is a group I made earlier to illustrate how the names appear in this display. Our new mix group will appear in this list after we create it.
To create this group, we first click on Audio 1, then we hold down the shift key while clicking on Audio 2. Both track names are now selected/highlighted.
[To deselect a track, click on an highlighted track. Or if all are highlighted, Shift-Click on one of them to deselect it.]
Next we select File|Group Selected Tracks. (The shortcut is Splat-G.)
A Dialog window appears, prompting us to name the Group. I'm using
"1/2" because it's clear & concise.
About the "Group Type": there are times
when we might want to group tracks for mixing or editing
functions only, but in this case we can use both Edit &
Mix. (Presumably, if we make any edits in our stereo music,
we want to edit both Left & Right at the same
place.) Pro Tools will also create a "Group ID"
letter that will be used in the mix display. After naming the group, press
"Ok."
Notice the new group name is displayed in the list. It's highlighted, meaning that it is active. (We can deactivate it by clicking on the group name.) Also notice the "b" on the fader slices indicating that group "b" is active on those faders.
The default for automation is for it to
be in the "auto read" mode, meaning that if any automation
instructions have been written, Pro Tools will follow them
during playback. To write the instructions, we click on
"auto read" to show a pop-up menu and select "auto write."
Now we can play our session and any fader moves we make on
group 1/2 will be recorded as automation
instructions.
Before we do so, there's one last item we might want to check, which
is a menu that serves as a kind of Master Automation Enable Window.
To view it, select Windows|Show Automation Enable Window:
<---- Here we can see that all the
parameters of Volume, Pan, and Mute, etc. are all enabled.
If we had automation data written for various tracks in a
session, but wanted to play the session back with no
automation, we could toggle the "auto suspend" button in
this window. That would disable automation for all tracks at
once. (This would "gray out" the little automation buttons
in the Edit & Mix windows.) As displayed here, all is in readiness to
write our automation. We can close this window and
proceed. [Tip: if you ever have a problem where Pro Tools
doesn't want to record automation, and you think that your
other settings are correct, check this window to make sure
that one of your parameters of Volume, Pan, or Muting isn't
disabled. Or if you get some warning message about the load
on the Mac CPU, you might disable automation types you
aren't using.]
Let's suppose that I want to do a slow fade-up on my music. First, I
press "Return" to place the Playback cursor at the very start of the
session, and lower the my faders so that they're fully closed. Then I
press the Spacebar to start playback. I used the mouse to gradually
bring up one of my Group 1/2 faders, listening critically to not only
my music but the other sounds in my session. I do some more
adjustments as needed. When I'm done, I press the spacebar again to
stop playback (which stops the automation writing.)
I've now written a series of volume graph points, and I can view them in the Volume Graph mode. My automation data looks like this:
You can see that there's a fairly gradual fade up over during the first 10 seconds, a slight level increase at 20 seconds, then there's an abrupt drop at 30 seconds and finally a quick fade out.
We could use the Grabber tool to go in and adjust some of these points. We can also use another automation mode to fine tune our work. This is called the "auto touch" mode. [Pro Tools will switch to this mode right after writing an automation pass if an option called "Write Switches to Touch After Pass" is selected in the Automation Preferences.]
In the "Touch" mode, Pro Tools will play back your automation as written. (You'll see the faders move in the Mix Window.) But if you use the mouse to "touch" a fader and make a new adjustment, Pro Tools will write this new adjustment to the existing automation. You can repeat the process as needed.
The potential is obvious: time permitting, you could get very finicky about mixing with automation.
One last tip about volume graphing: when you're switching back and forth between volume graph and waveform displays, and moving regions around, it's easy to forget that while much of the volume graphing "sticks with" the regions, some volume breakpoints can get "left behind" in the tracks. And sometimes, after volume stamping, regions undergo further edits which can result in unexpected volume graph changes. So it's a good idea, at the end of a complicated session of editing & automating, to switch all tracks into the Volume Graph mode to look for any left-over automation points, errors, etc.that may need deleting or fixing. (To switch all track displays at once, hold down the Option key while choosing the display type.)
Besides level adjustments, you can also automate pans in a similar way. Just select "pan" instead of "volume" from the track display. You'll notice a vertical bar that represents a continuum between Left and Right:
In the above example, our first region (a biplane by) will play in the Center. Using the Grabber, I've created some breakpoints so that the second biplane sound will start in the Left and pan to the Right.
Again, you can also choose to write these pans with the Pencil Tool or while listening in "real time" by moving the pan sliders during an "auto write" pass.
That's pretty much it for basic automation.
[You may have noticed that there's also an "Mute" automation mode for muting selected portions of a track. Experiment with it if you like. Frankly, there are easier ways to Mute regions -- you can just select a region and choose Edit|Mute Region (the shortcut is Splat-M.) There is a subtle advantage to creating an automated track mute, though. On the TDM systems, if an Option called "Mutes Frees Voice" is enabled, it means that if you Mute Track 2, Voice 2 for a spell, during that time any regions that occur on the next track that is also assigned to Voice 2 would be free to play. See, ordinarily track 2 regions would take precedence, but since track 2 is muted at that point... Well, I did say that it was a subtle advantage. Usually if you have a region that you don't want to play, you wouldn't bother leaving it in the track -- you'd clear it, or at least mute the whole region.]
Go to Mixing Part II: Real Time Plug-ins & Audiosuite Plug-ins.
Copyright ©2000 by Rodger Pardee