We begin a two-part tutorial explaining Pro Tools' powerful facilities for automating your mix.
Pro Tools has one of the most sophisticated automation systems of any mix environment that money can buy. What's more, the LE and Free versions of Pro Tools share nearly all the features of the TDM 'Daddy' configurations. Various automation issues have crept into this Pro Tools column over the past two years, but this month we're going to give the subject the undivided attention it deserves.
Mixing is undertaken to meet two requirements of the music recording process: one artistic and one technical. Artistically speaking, the mix stage lets you balance and blend the elements of your recording in terms of level, position (panning) and tone (EQ). The technical side is about getting the best out of (and respecting the limits of) the recording medium/format where the music will end up being stored and reproduced. This is mainly about controlling the dynamic range of the sounds and complete mix (the difference between the quietest and loudest parts of the music).
With a simple song that doesn't change much in terms of level and instrumentation, it's possible to play through your session several times while adjusting mixer and plug-in settings until you achieve the sound you want. The song can then be bounced to disk and your project is complete. More often, though, a particular static setup of the mixer will not suffice for the whole song, so changes need to be made at particular points throughout to handle variation in instrumentation or arrangement and to add dynamics and interest. Like many audio mixers and programs, Pro Tools can store parameter data for the mixer with respect to time, resulting in the mixer changing throughout the session. These changes fall into two categories: dynamic automation, where control movements are recorded in real time for future playback, and snapshot automation, where a complete (static) mixer state is taken and applied at a point in time.
For many people, the first taste of mix automation occurs when a particular plug-in effect is required at one point in the song, but not in others. A simple way to achieve this is to insert the plug-in on the track, but bypass it during the parts of the track where it's not required. The basic parameters on the mixer (faders, pans, mutes and sends) are always ready to be automated, but plug-in automation must be pre-enabled before you can use it. This is achieved from within the plug-in window by pressing the 'auto' button (which appeared as 'automation' in earlier versions of Pro Tools), leading to the window shown above.
In the screenshot (right) you can see that I've already added 'Master Bypass' to the automation-enabled list on the right, meaning I can now automate this switch either by real-time recording or off-line editing. The second screen (top) shows that the track view now has an option to view the automation graph for this plug-in's Master Bypass control. I can now change to this view and use the Pen tool to draw in the data I require, which in the case of a bypass switch is a section where the graph is at the Bypass Off position. When automating sudden switches like this it's important to try to drop the changeover point during some silence to avoid clicking or glitching.
Now that we've tried a simple mixer edit operation, let's go for some dynamic mixer movement. At the end of the vocal track from the last example, the performance gets quiet so we're going to push the fader at that point. The first step is to select one of the automation recording modes on the track in question. Write, Latch and Touch modes will all do the trick (see 'Automation Modes' box), but for this example I'll use Latch mode. There's very little reason for ever using the basic Write mode, so it's a good habit to start using Latch or Touch from the beginning.
Now, open the Automation Enable window from the Windows menu and check that Volume is enabled (white is enabled, grey is disabled). This window can be used to make previous automation recordings 'safe' from future automation recording, but there's no real stress because as long as you use Latch or Touch modes you'll only be recording the specific parameters that you move. For this situation I started playback from somewhere before the point in question, and moved the fader as required to even out the vocal performance, stopping shortly after. The screen shot above shows the track in Volume display with the new fader automation displayed. The fader will now follow this graph always unless the track is in Auto Write or Auto Off modes. We'll return to this example next month as it raises an issue about how different systems handle automation...
Each track in the Pro Tools mixer has an independent automation mode selector. These can be assigned individually or, by holding down Option, you can switch all to the same mode at once.
- Auto Off: The mixer channel will ignore all automation graphs ('playlists') in the track.
- Auto Read: Automation will be followed at the playback or cursor position so long as the global automation Suspend button is not on.
- Auto Write: From the moment playback commences, any automation-enabled parameters will be written to the track. This mode is probably best used only if you want to set some parameters to their desired recording positions before you hit Play.
- Auto Touch: A punch-in type mode, where automation is only written while you are actually moving or holding a control.
- Auto Latch: Automation only starts being recorded from the moment you alter a parameter, and continues until you stop playback even if you subsequently 'let go' of the control. This is probably the best starting mode for fader automation.
After an automation recording, you can Undo straight away if you're not happy. If it's mostly good but needs a tweak, switch the track into Auto Touch mode and play through. You can now grab the fader and make your adjustment, then let go and allow the fader to glide back to catch up with the previous data. The time it takes for the fader to glide back out of a Touch recording is set by the 'Auto Match Time' setting in the Preferences (Automation pane). This defaults to 1000ms, which is often too slow: 250ms will give you a much tighter punch-out from a Touch pass. If it's proving tricky to get the exact movement you want, it may be better to edit the graph instead. There are a few ways of doing this, each linked to different edit tools. The simplest but most heavy-handed method is to use the Pen tool in Freehand mode and simply draw into the graph with the mouse. For smooth transitions such as fade-outs there's the Line sub-mode of the Pen tool. When the Grabber tool is selected, the cursor becomes a pointing finger that can be used to create and move breakpoints. You can also Option-click breakpoints to delete them.
The Selector can be used to highlight sections of the automation, allowing other subsequent editing techniques. The most basic of these would be hitting Delete or Backspace to remove the section. A subtle and often more useful variation of this edit is to use a Cut (Command+X on the Mac or Ctrl+X on Windows) which causes breakpoints to be created at the boundaries of the selection, leaving all areas outside unaffected. With some automation selected, another trick is to use the Nudge keys ('+' and '-' on the numeric keypad) to edge the section earlier or later, which is great if you reacted too slowly during the record pass.
Finally, a really useful technique with a selection is to switch to the Trimmer tool and drag vertically within a highlighted area. This will scale the whole graph up or down without losing the overall shape (see screen shot). While Auto Touch mode is useful for punching in and rewriting sections of automation, there is a subtler 'tweak' mode called Trim. Any of the modes can be switched into Trim, but I'm going to concentrate on a mode called 'Write while Trim' which is the most useful. Switch a track that already contains fader movements into Write mode, then click again on the automation mode selector and tick Trim. The fader cap will change to a gold colour, and will jump to the 0dB or null position. When you play across your existing automation you can now make adjustments to the overall level of the track without disturbing the basic shape of the moves you already made. In other words, if you pull the fader down to -6dB while making the pass, all the existing automation will remain but be scaled down by 6dB. When you stop, the graph will be redrawn incorporating the new 'delta' data -- a method sometimes called coalescing. Cleverly, even though you are using a variant of Write mode, plug-ins are assumed to be in Latch mode so that you don't stomp all over your effects automation while trimming.
Next month, we'll look at some further automation concepts and techniques, such as working with snapshot automation, dealing with 'anchored' automation as opposed to 'virgin territory', and advanced automation editing.
- Don't overlook the humble Mute Region command, accessed by selecting a MIDI or audio region and choosing Command+M/Ctrl+M (Mac/PC). This can be a really useful edit function when compiling vocal tracks or quickly trying out alternative arrangements.
- With Quick Punch enabled, Pro Tools has to pre-allocate recording space the moment you hit Play (and start recording in the background), which can take several seconds when you have a large number of tracks record-enabled. You can reduce this time significantly altering the Open Ended Record Allocation setting in the Operation Preferences. Switch from 'Use all available space' to 'Limit to x minutes' and set no more time than you are likely to need.
A quick diversion here to talk about mastering or 'maximising' plug-ins: tools that help out with managing the dynamics of a mix. The main job performed by effects such as Digidesign's Maxim, Waves' L1 Ultramaximiser and TC Works' Master X is to limit the loudest parts of the mix, allowing you to make a mix sound much louder without turning up your speakers. This may sound paradoxical, but think about it this way: when you're listening to a CD or record, there's a certain maximum loudness that the medium can represent (a row of 16 '1s' on a CD, or the biggest wiggle in the vinyl before the needle flies off). This maximum will correspond to an actual sound pressure level coming out of your speakers, depending on the position of your hi-fi's volume knob.
Now, when you make your final mix, the very least you can do to optimise for CD is to make the loudest part of the mix line up with the maximum level of the Pro Tools mixer before a red light. This means that you're using 'all 16 bits' to encode the music. But what you'll notice is that the very loudest thing that happens in your song now defines the level at all other points (which are somewhere down the scale from the loudest bit). So if you want to bring up the average level or energy of the whole mix, you only have one way to go which is to pull down (limit) the peaks in the song. Now when you line up the peaks with the maximum level, all the other sounds are not so far down the scale. This is exactly what maximisers do: they limit the peaks, then push up the whole mix into the clear headroom that is freed up.