Music 265B Week 09 Editing, Part 3
PDF version available HERE
So far, we have used the Smart Tool to cut, drag, splice, and assemble a good master performance. We used Strip Silence to cut down on unwanted leakage, and Beat Detective to clean up our performance’s rhythmic accuracy. Elastic Audio allowed us to stretch and warp our audio to fix up any additional mistakes. But what about tuning and pitch? A musician could have accidentally played the wrong note on the right rhythm, or the singer could be out of tune. We can attempt to fix some of these mistakes through an editing process known as Pitch Correction: altering the intonation on any given track.
Pro Tools has some built-in functions that let us alter a track’s pitch, but for inexperienced editors and non-musicians, identifying a “bad” note can be fairly difficult and subjective. Because of this, we will also look at a few Third-Party Plug-Ins (plug-ins that do not come standard with Pro Tools: they must be purchased separately) that make this task easier. That being said, this is where a musician’s theory, harmony, and ear-training skills come in handy.
Just as we had to prepare our clips for Beat Detective, we have to do a bit of preparation for pitch correction. First, we need to identify the “bad” notes. They may be rhythmically on the grid, but the note may sound dissonant or out of place against the other members of the band. We can say the note is wrong if the player accidentally played a different pitch – they struck the wrong note, fretted the wrong string, or sang the wrong pitch in the musical scale even though the part was rhythmically accurate. For example, if a piece written is in the key of C Major, the note C# is probably a wrong note. The interval distance between the notes C & C# is called a Semitone, or half-step. In pitch correction, Coarse adjustments are usually measured in semitones.
Alternatively, the musician may have played the right note on the instrument, but the pitch may have been slightly too high (sharp) or slightly too low (flat). In pitch correction, these smaller Fine adjustments are called Cents. In western music, there are 100 cents in a semitone, and 12 semitones in an octave.
In either case, we need to identify where the trouble spots are, and determine if these bad notes can be fixed. Vocals can be especially problematic. Keyboards, guitars, brass, and woodwind instruments may have poor intonation from time to time, but they usually have a specific key, valve, fret, or string assigned to specific pitches. Because of this, they are more likely to stay on a consistent pitch. Vocalists do not have that, so they are prone to drifting around, and sliding to or from note to note – if they even land on the right note in the first place.
We may run into a few problems. Pitch correction software can easily identify and edit Monophonic material; that is any instrument or sound source that produces one note at a time, like a saxophone or a single human voice. However, most pitch correction software can’t understand Polyphonic material; that is any sound containing more than one pitch or noise. This includes everything from an instrument playing chords, to another instrument’s Leakage our track. If we don’t have proper isolation, we may not be able to correct a track’s pitch without causing other problems. Let’s say we have two recorded instruments, with one leaking into the other’s track. If one of the instruments is in tune, while the other is a half-step out of tune, altering the pitch on the out of tune track will also alter the leakage on the same track. Because of this, we may have to search through our other takes in order to find a clip of that instrument playing the correct pitch. In that case, we can just copy and paste over the bad notes. Otherwise, we may just have to find a clip that is “close enough” to the right pitch. If we have an isolated monophonic track (no chords and no leakage), we can easily correct the pitch, or alter the track to create new harmonies.
Editing With Elastic Pitch
Just as Elastic Audio can warp and stretch the rhythmic timing of an audio clip, Elastic Pitch can non-destructively alter the intonation of an audio clip. To activate it, set the track’s Elastic Audio Plug-In Selector to Polyphonic mode – it’s on the edit window, beneath the track’s name. Next, highlight and separate the note or notes we want to correct. Right click on the note, and select Elastic Properties. When our clip is selected, we can alter the intonation with the Pitch Shift settings in this Elastic Properties window – we can ignore the other settings for now. Under Pitch Shift, we can raise or lower the pitch in Semitones or Cents. Enter a value, and the clip will change pitch. How much should we adjust it? That depends. We don’t have any visual representation of the pitch, so you’ll have to rely on your ears for this method.
Let’s assume our track is in tune, but we want to alter the melody or create a new harmony. For example, imagine an instrument playing a Major scale: “Do Re Mi Fa So La Ti Do.” With Elastic Pitch or any other pitch correction software, we could change this from Major to a Minor scale fairly easily. Separate and select all of the “Mi” notes, and lower them by 1 Semitone with Elastic Pitch. The scale is now in the Melodic Minor form. Next, lower the “La” notes by 1 semitone – we are now in Harmonic Minor. Lastly, lower the “Ti” by 1 semitone. We are now in Natural Minor. Like Elastic Audio, Elastic Pitch and other forms of pitch correction sound best when they are used in small increments. Extreme edits can have unnatural sounding artifacts.
We can alter pitches in a few other ways. Elastic Audio & Elastic Pitch are non-destructive editing tools. They process our audio clips in real time, leaving the original clip unchanged: if we make a mistake, we can undo it. Audio-Suite plug-ins let us edit, and render a clip into a new audio file. Let’s go back to our original clip of the Major scale. Separate the notes into individual clips. Now, instead of editing the notes with Elastic Pitch, select the note, and choose Audio-Suite > Pitch Shift > Pitch Shift (or Pitch II) from the dropdown menus. Once again, make our adjustments: select the “Mi” note, and lower the Coarse adjustment by 1 Semitone in the Audio-Suite plug-in window. We can preview this change by clicking on the Speaker (called Preview Processing) icon at the bottom of the Audio-Suite window. If we like that change, press the Render button to turn this highlighted section into a new Audio File.
Mix Window: Plug-Ins
Audio-Suite Plug-Ins and changes made in the Edit Window will only affect specific sections of the track: we may only want to change a few notes, or change the tone of a specific clip without affecting the entire track. However, we may need to affect the entire track from time to time. In that case, we can use pitch correction plug-ins on the track’s Inserts in the Mix Window. Switch over to the Mix Window (shortcut ⌘=). On the track’s Insert, and use the dropdown menu to locate our pitch shift plug-ins. We can use the same Pitch Shift plug-ins here, but shifting the adjustments up or down by a few semitones or cents will Transpose the entire track’s pitch up or down.
Third-Party Plug-Ins: AutoTune
We can easily re-harmonize a track with the standard plug-ins and Elastic Pitch functions in Pro Tools, but fine-tuning our out of tune tracks can be a challenge. Because of this we often turn to Third-Party Plug-Ins (plug-ins that do not come standard with Pro Tools) for some of our detailed work. Antares AutoTune is a common one, known in the industry for its “T-Pain” vocal sound. This plug-in analyzes the incoming signal, and retunes the pitch to the nearest note in the musical scale. Because of this, once we dial in the right settings, we can usually let the plug-in do the rest of the work for us. Let’s take a look at some of these settings.
Input Type refers to the kind of sound source we’re dealing with: voices come in different registers from the high-pitched female Soprano & Alto to the lower male Tenor & Bass voices. There are options for standard Instruments & Bass Instruments as well. Select the appropriate Input Type for each track.
The next set of options requires a bit of music theory. We need to adjust the Key and Scale options to fit our song. For example, a piece could be written in C Major, E Harmonic Minor, or a more exotic scale. If the piece is not strictly Diatonic (only using notes in the same key/scale), then it may be easier to set our scale to Chromatic, which uses all 12 notes. Alternatively, we could program our AutoTune plug-in to Remove or Bypass specific notes in the scale.
We have a few pitch correction controls that will drastically affect our processed audio. Retune Speed adjusts the time the plug-in takes to correct the pitch. A fast speed provides more of the plug-in’s characteristic robotic and hard pitch correction, while a slower speed sounds more natural. Vibrato is the natural rapid pitch variation that singers use. We can recreate a vibrato effect in AutoTune, use the singer’s vibrato, or ignore it entirely.
This “set and forget” method is ideal when our tracks are already “close enough” to the right pitch. For sloppy parts and inaccurate singers, we need to use more extreme methods.
Third-Party Plug-Ins: Melodyne
Celemony’s Melodyne is one of the best pitch correction programs available today. Unlike most other pitch correction software, it is capable of analyzing and editing Polyphonic material. Before we use Melodyne, finish all of your edits in the Edit Window: we need to finish chopping up, moving, and fading our clips before we start using Melodyne. To use it, activate the Melodyne plug-in on the track’s first Insert. In the Edit Window, highlight the entire track, from the first clip to the last. Next, open the Melodyne plug-in and adjust our settings. Just like Elastic Audio, Melodyne uses a few different algorithms, depending on what kind of editing we plan on doing. In the Melodyne plug-in, click the Algorithm menu option, and select Melodic. Next, pick the Key & Scale type by right clicking on the Piano-Roll: the vertical pitches on the side of the editor window. Melodyne may try to analyze this by itself during the next step, but it may be incorrect depending on how badly out of tune our track is: always choose the key & scale type ahead of time when you can.
Next, press the Transfer button. When we press play, our track will now be recorded into Melodyne. This means the track will now play back from Melodyne as well: if we make any more edits in the Edit Window, they won’t be heard until we transfer them into Melodyne again. Once the track has finished playing, Melodyne will analyze the recorded audio, and organize the different pitches onto the lanes in the piano-roll. When we’re done transferring, we should see the Pitch Centers (the colorful waveforms centered around a specific note), and the Pitch Drift (the wavy line drawn through the notes).
This next task requires a bit of music theory skills. Melodyne will analyze and display what it thinks it heard. We need to play back the track in Melodyne, scan through and check for any additional mistakes. Let’s say our piece is written in the key of C Major again. If the sloppy singer sang Do & Re (the notes C & D) as two slurred 8th notes, Melodyne might incorrectly analyze this as one quarter note centered on the note C# or Db: a semitone between C & D. We will need to use Melodyne’s Note Separation Tool (the line with two arrows) to break up this note. How do we know when we have to do this? You’re a musician; use your eyes & ears.
As far as pitch is concerned, Melodyne will display the note’s current pitch center as the colored waveform. Melodyne will display where it thinks the correct pitch should be as a shaded box. We can alter the pitch in a few ways. First, click and drag to select a musical phrase: work in small sections by selecting a few notes at a time. Next, click the Correct Pitch button. A menu will appear with two sliders. Correct Pitch Center will drag the waveforms toward the shaded areas: 0% will not change anything, while 100% will center the pitch on the “correct” lane. Correct Pitch Drift will center the note’s vibrato (the wavy line) on the note. Experiment with the different settings until you find an option that works. We can undo these edits by pressing the Undo button in Melodyne (the counterclockwise arrow icon).
Alternatively, we can edit these pitches manually with the Pitch Tool (next to the main pointer tool – right click on the Pitch Tool for more options). With the Pitch Tool, simply Double Click to center the pitch on the nearest lane, or Click & Drag to move the centered pitch to a different note. Holding down the Option button while dragging will let you adjust the pitch in cents instead of semitones.
Right clicking on the Pitch Tool reveals a few more options. The Modulation Tool alters the vibrato on any given note. Double clicking on a note with the Modulation Tool will eliminate the vibrato. Clicking and dragging up will widen the vibrato, while dragging down will reduce it.
The Pitch Drift tool corrects bending pitches: if the note starts flat and ends sharp, the Pitch Drift tool will center and even out the pitch’s drift without affecting the vibrato.
If some of the notes end up sounding too processed or fake when we repitch them, the Formant Tool might be able to help correct some of this. If the note is pitched up too high, click and drag the formant bar down. If the note is pitched too low, drag the bar up.
The Amplitude Tool will raise or lower the volume of individual notes. Double click to mute, drag up to raise the volume, and drag down to lower it.
The Timing Tool works like Elastic Audio. Double click to quantize the note to the nearest grid marker, or drag it forward or backward in time to stretch & warp the note’s timing.
When Melodyne transfers and edits our audio clips, it creates a new temporary file somewhere on the system’s hard drive. If we take our session home or to a different studio, this file may not come along for the ride. To make a permanent copy of this newly tuned track, we can simply record the output back into Pro Tools on a new track. If we are tuning a mono track, create a new mono audio track. Disable any extra plug-ins and sends on the Melodyne track: leave Melodyne active. Next, assign our Melodyne track’s output to an empty bus (one bus for mono tracks, two for stereo). Assign our new track’s input to that same bus, and arm the new track. Arm the transport and record until everything has been recorded onto the new track. After that, we can deactivate & hide the old Melodyne track. This way, we have our original content, and our newly tuned track safely archived in our session.
That brings us to the end of the editing phase. So far, we learned how to…
- Select, separate, slide, copy, cut, paste, and create fades.
- Make a composite “master” performance out of all of our recorded material
- Use Strip Silence to clean up our noisy tracks
- Use Beat Detective to quantize our audio
- Use Elastic Audio to warp our audio
- Use Elastic Pitch & AudioSuite plug-ins to harmonize our tracks
- Use AutoTune & Melodyne to fix our tracks’ intonation
- Remove the unused material from our sessions
When all of these editing tasks are done, we can move on to mixing.