Music 265B Week 08 Editing, Part 2
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Remember, during the editing phase, we try to accomplish three goals.
- Assemble the best performance out of all the recorded material.
- Fix any mistakes: correct pitch and adjust rhythmic accuracy as needed.
- Clean up, polish, and prepare our tracks for the mixing phase.
By now, we should be able to accomplish that first goal using the skills we developed in the previous lesson. Those are:
- Analyzing, selecting, and separating clips.
- Cutting, copying, and pasting clips into different Playlists.
- Moving, sliding, and nudging clips forward or backward in time.
- Creating fades: fade in, fade out, and crossfades.
This part of the process can be long and tedious, but it needs to be done manually. Pro Tools has some semi-automated editing functions that can do a lot of the tedious jobs for us, but we need to make sure our tracks are free of any obvious mistakes first. The computer doesn’t know if a musician played a note on the wrong beat: it can only determine that there is a transient or peak in the audio waveform near one of the beat markers on the grid. We have to decide if that part is right, wrong, or “close enough for punk rock.” Ultimately, we have to analyze, separate, move, and fade the clip into place. We may need to do this hundreds or thousands of times throughout the session. Let’s look at some of the tools that make this part of the job a little easier.
Strip Silence is a non-destructive editing command in Pro Tools that functions like a noise gate. It analyzes audio clips, finds the loud peaks in the waveform, and deletes the quieter spaces (silence) in between each peak. Strip Silence is ideal for cleaning up some of the leakage in our noisy drum tracks. For example, in a typical drum recording, we have individual microphones on every part of the kit. Even with ideal microphone placement, our kick track will have a strong signal from the kick drum, with some minor leakage from the snare & toms. Our snare track will have a loud snare signal, with leakage from the rest of the kit, and so on. That leakage can either add unwanted noise to the overall drum sound, or it could be a necessary characteristic part of the drum set’s sound. If we want to remove some of it, Strip Silence is our best tool for the job.
To use Strip Silence, highlight a small section from one of our drum tracks and select Edit > Strip Silence (shortcut ⌘U). When the Strip Silence Window appears, little white boxes might form around the peaks in our audio clip. These boxes represent the parts of the clip we want to keep: we use the sliders on the Strip Silence Window to adjust the boxes. Strip Threshold determines how quiet a sound has to be in order to be considered Silence: the space outside the white box. Going back to our kick drum example, we want to adjust the Strip Threshold until the box includes only the kick drum’s peaks: we want the leakage to stay outside of the box. This can be tricky if the drummer plays with lots of dynamic contrasts: we don’t want the instrument’s softer hits to be considered part of the silence. If this is a problem, separate the softer parts of the drum tracks into smaller sections and start over.
When peaks appear close together, Strip Silence may include two or more peaks in each box. In the end, we want to have one peak per box. To fix this, move the Minimum Strip Duration slider. Sliding it all the way to zero milliseconds may create hundreds of individual boxes inside the “Silence” area, while sliding it all the way up will usually select the entire audio file. Adjust it until we see one box around each of the peaks we want to keep. In the end, we don’t want to chop off the beginning of the drum’s attack sound, and we don’t want to cut away too much of the sound’s decay at the end of the waveform. If needed, we can adjust the Clip Start Pad to move the start of the box, and the Clip End Pad to move the end of the box. Adjust all of the sliders to include the parts of the waveform we want to keep.
When we’re ready, we have a few options available at the bottom of the Strip Silence Window. The Rename button will let us rename our new clips. Extract will delete the parts of the clip within the white boxes (our peaks). We can use this to hear the “Silence” that we want to delete. If you hit extract, you can undo this by pressing ⌘Z. Separate will break the file up into individual clips: peaks within the white boxes, and silence outside. However, when we use the Strip Silence command, we usually want to use the Strip command: this will turn our peaks into individual clips, while deleting the silence. All of these functions are non-destructive, so we can undo or alter the edits at any time.
After we Strip Silence, play the clips back and confirm that we like those edits. There may be some unnatural entrances & cutoffs at the start & end of each clip, but we may be able to correct this with some fades. Rather than manually fade in & out of each clip, we can affect all of these clips at once. Highlight all of the clips, and bring up the Batch Fades menu with ⌘F. Batch Fades use the same custom fade menu found under the Edit > Fades > Create menu. Unlike individual fades, Batch Fades create multiple fades across several clips. In this menu, we can adjust the Shape, Placement, and Operation of each fade, most importantly how long the fades will be, measured in milliseconds. Once you have picked your settings, press OK to create the new batch fades. We now have individual, isolated drum hits that can be dragged around and aligned to the grid, or lined up with another player’s performance.
Beat Detective is a powerful editing tool that can quantize our audio & MIDI drum tracks. Because of this, it works best when editing tracks that were recorded to a click. It can line up every peak to the nearest point on our grid. This can either tighten up the drummer’s performance, or make the player’s natural feel sound robotic depending on how you look at it. Remember, Pro Tools can’t tell if the drummer made an obvious mistake. If a drum hit was supposed to be played on the downbeat or on an odd 16th note, we need to manually fix those mistakes first until the part is at least “close enough.” With that in mind, we also need to determine what the drummer is playing: what is the smallest rhythmic value being played? Is the drummer swinging? Is the drummer playing triplets? But how do we figure all of this out? You’re a musician; use your ears.
To start using Beat Detective, highlight a small section across all of our drum tracks. Bring up the Beat Detective window by selecting Event > Beat Detective (shortcut ⌘8 on the number pad). Select the Clip Separation tab under the Operation section of the Beat Detective window. Under Selection, set the Contains dropdown menu to the smallest rhythmic value used in this performance. Does the drummer play 16th notes? If so, then choose 16th notes. What about Triplets? If yes, select the 3 option. If not, leave it unchecked. Once we have our settings, press the Capture Selection button. This will set the Start Bar/Beat & End Bar/Beat values to the current highlighted section. Next, move over to the Detection section (in Clip Separation mode). Click the Analyze button, and select Sub-Beats under the Resolution settings. Gradually raise the Sensitivity slider. As the slider moves toward 100%, lines marking what Pro Tools thinks are our drum hits will appear. A drum hit in one track will draw the line through all of the highlighted tracks. This is where Beat Detective will separate our clips in the next step. If we raise the slider too far, Pro Tools will display some false-positives: peaks that it thinks are drum hits. If the slider is set too low, it won’t select all of the hits. Adjust the slider until only our drum hits are selected. When we’re ready, press the Separate button at the bottom of the window (in Clip Separation mode).
With our clips separated, we can move on to the Clip Conform tab under the Operation section of the Beat Detective window. This Conform option will slide our clips around on the grid. The Strength slider determines how accurate the quantization will be. 100% will lock the clips to the grid, like a drum machine: the drummer’s original feel (or sloppy playing, depending on how you look at it) will be lost, and the tracks may sound like a drum machine played them. Exclude Within will preserve some of the drummer’s original hits if they were “close enough” – adjust the slider to determine how close that should be. The Swing slider will swing the performance using an 8th Note or 16th Note swing. Adjust these settings to your liking, and click the Conform button to move the clips into place. Play the section to confirm that the clips are rhythmically correct. If they are not, Undo this Clip Conform, change the settings, and try again. Even if the new clips are on time, there may still be various clicks, pops, and gaps in between these new edits. To correct this, we use the Edit Smoothing function in the Beat Detective window. This will do two things: Fill Gaps will, as the name states, close the gaps between each clip, just like we would with the Trimmer tool. Fill And Crossfade will take this one step further by adding fades & crossfades between each clip. We can adjust the Crossfade Length to our liking as well.
Once again, listen back to the edited section to make sure everything is ok. At this point, we may still have to make some manual adjustments. Go through and check each crossfade to make sure the hits we wanted to keep weren’t accidentally chopped off or hidden within a fade. We may have to use the Smart Tool to adjust the size and placement of some of the new crossfades. To avoid potential phasing issues, move the crossfades across all of the edited drum tracks together in time.
Tips and Tricks with Beat Detective
The method we just used will affect all of our drum tracks; every hit from every drum will be quantized. On the other hand, let’s assume we want to keep the drummer’s overall groove, but we want to tighten up the performance around the kick & snare hits. Instead of analyzing all of our drum tracks, we can start with just our kick & snare tracks (or any other track for that matter). Following the same procedures, we should select and analyze only those tracks. Highlight, capture, analyze, and adjust the sensitivity until only our kick & snare hits are selected. Next, select all of our other drum tracks in time, by Shift Clicking on them. DO NOT hit Analyze again. Our current kick & snare analysis markers should appear across our other drum tracks. From here, we can continue editing normally: separate, conform, and smooth out the clips. Be sure to double-check the crossfades for any unintentional cuts. If everything worked properly, we should have quantized our kick & snare, and synced the rest of our drum tracks to those edits.
Beat Detective serves some other functions as well. When we Quantize MIDI information, we have the option of locking our notes to an absolute time reference (bars, beats, 8th notes, etc), or quantizing to a set of Groove Templates – timing references found in programs like Logic, Cubase, and others. We can use these templates to quantize our notes to one of the preset grooves, or we can use our drum tracks to create a template of our own. In Beat Detective, select the Groove Template Extraction option. Follow the normal Capture & Analysis methods described above, but instead of separating and conforming our drum tracks, use the Extract option to create a new template. In the Extract Groove Template, we can leave a comment describing this new template. We can save it in one of two ways: we can save this template permanently with the Save to Disk option, or make a temporary version with Save to Groove Clipboard. With this feature, we can quantize any MIDI data in our session to this new customized drum groove. To use this template, highlight some MIDI notes and bring up the Event Operations > Quantize window with the shortcut Option 0. Under the Quantize Grid option, we can find our new template in the dropdown menu.
Beat Detective can perform one last function with the Bar/Beat Marker Generation functions. To make our lives easier when it comes to editing, we usually have the musicians record with a click track. This ensures that all of our tracks will be consistent from take to take, and they will easily sync to our tempo and grid settings. However, we still run into situations where the band did not or could not record to a click, but we are expected to fix everything as though they did, or record MIDI data on top of these inconsistent tracks. With the Bar/Beat Marker Generation functions in the Beat Detective window, we can make our session’s Tempo ruler conform to our audio tracks. Open up beat Detective, select Bar/Beat Marker Generation, Capture the Selection, Analyze, adjust the Sensitivity, and click Generate. A Realign Session warning will appear, giving us an option to move any tick based tracks. We will discuss the difference in a moment. In this case, we will use the Preserve Sample Position (Don’t Move) option. With this selected, our Tempo Ruler will conform to match the tempo shifts associated with this section. It may change from note to note, adjusting to fit the players’ inconsistencies.
Ticks & Samples
Tracks in Pro Tools have two kinds of Timebases: Sample based, and Tick based. Sample based positions are absolute time references, associated with the minutes & seconds ruler. For example, one minute into the session will always occur 60 seconds away from the start of the session. Tick based positions are relative positions, associated with the bars, beats & tempo rulers. For example, the downbeat of bar 3 can occur 4 seconds into the session, or 14, depending on the tempo. Audio tracks are usually Sample based, whereas MIDI & Instrument tracks are usually Tick based by default. We can switch between these timebases with the Timebase Selector, located beneath the track name on the edit window: Sample based tracks have a little blue clock icon, and Tick based tracks have a little green metronome icon. Click on the Timebase Selector and pick a timebase. We will use this function extensively in the next steps.
Elastic Audio is a powerful editing function that lets us speed up, slow down, stretch, and warp our audio tracks in real-time without changing pitch. We saw some similar effects with our Trimmer Tool’s TCE (Time Compression Expansion) mode, but Elastic Audio lets us do more. We can easily speed up or slow down the entire session by changing the manual tempo. First, select all of our tracks, and change their Timebase to Ticks: click on the Timebase Selector icon, and select the green metronome icon. Next to the Timebase Selector is the Elastic Audio Plug-In Selector. Click on it and select the setting that is appropriate for the current track: Rhythmic for drum tracks, Monophonic for instruments that only produce one note at a time (vocals, woodwinds, and so on), Polyphonic for instruments that can produce more than one note at a time (keyboards, guitars, and so on). The Varispeed option will behave like a tape machine: when the clip gets stretched to play slower, the pitch will go down. When it is shrunk to play faster, the pitch will get higher. We won’t use Varispeed for any of these edits. For now, stick to Rhythmic, Monophonic, or Polyphonic, depending on the type of instrument we’re editing.
Locate the MIDI Controls on the edit window, next to the Transport. If they aren’t visible, select View > Transport > MIDI Controls, and make sure MIDI controls is checked. Next, disable the Conductor Track – the button under the MIDI controls that looks like a conductor with raised arms. The Tempo Ruler should now say “Manual Tempo.” We can manually set a new tempo for the session: change the Tempo in the MIDI Controls section. Since our tracks were converted to a Tick based reference, they will stretch to match the new tempo. This is a quick way to change the overall tempo, but this can create some problems. If our tracks have a lot of leakage, then this stretching could cause some serious phasing issues between tracks. It may be necessary to use Strip Silence and other methods to mitigate some of these problems.
Elastic Audio is ideal for small adjustments. If Pro Tools thinks the audio clips are being warped too much, the clips will turn reddish-orange. However, we still need to use our ears. If we hear noticeable artifacts and distortion from this processing, undo it and try a different approach. Elastic Audio’s ideal use is for Warping audio: stretching and sliding individual transients around inside a clip. This is an excellent tool for cleaning up sloppy performances. To warp a clip, change the Track View Selector from Waveform to Warp in the dropdown menu. The clip will turn grey, and small black lines will appear on each transient in the waveform. These are Warp Markers. If needed, we can add additional warp markers by Right Clicking a point with our Selector Tool selecting Add Warp Marker.
At this point, simply clicking and dragging a warp marker will stretch the whole clip. If we only want to affect one transient/marker, we need to Double-Click on some of the warp markers in order to Lock them in place. Lock down the warp marker in front of and behind the marker that we want to edit. This will ensure that we only warp the one marker in the middle. After that, we can Click & Drag the warp marker we want to alter until it is in line with the beat. Alternatively, we can simply Shift Click on the marker we want to edit: this will lock down the marker before & after the one we want to edit.
For a practical application, let’s assume we’re done editing our drums: after using Beat Detective, the drums are set to the grid, and we’re happy with the drummer’s groove. After all of those edits, our bass track might be a little out of sync with the drums from time to time. Some notes may be on point, but others may be a too far ahead of or behind the beat. We can warp the bad notes into place by locking down the good notes, and sliding the bad ones into place. We can use a few tricks too. Elastic Audio can be Quantized, just like MIDI. Select that bass track, and activate the Warp track view. Next, bring up the Quantize window with the shortcut Option 0. From here, we can adjust our settings as needed. However, we did use Beat Detective to make that Groove Template earlier in this lesson. Go to the Quantize Grid dropdown menu, and find our groove template near the bottom of the list. Once we are done adjusting our settings, hit the Apply button to quantize the clip. Once again, listen back to the edited track, and make any adjustments as needed.
Finishing the Editing Phase
Using the skills we developed in the last lesson, we assembled the best composite performance out of all of our recorded material. Using the skills we discussed in this lesson, we can fix a lot of the minor mistakes, and adjust the rhythmic accuracy of any given track. To clean up and polish our tracks, we just need to trim away the noise & dead air, and use fades to avoid any unwanted clicks and pops as we transition from clip to clip. Once that is done, we can move on to mixing.
When we are completely satisfied with our edits, we can remove the unused material from our session. However, before we do this, be warned: if we made a mistake and need to go back and fix something, we won’t be able to retrieve a file that has been deleted. More often than not, it’s better in the long run to save everything on a hard drive until the entire project is complete. Even then, it’s still safer to keep everything archived on a hard drive. Do not clear or delete your clips unless you know what you’re doing.
Before you do anything, Save this current session. Look for the small dropdown arrow next to the Clip List. If you don’t see the Clip List, select View > Other Displays > Clip List. In the Clip List dropdown menu, choose Select > Unused (or use the shortcut Shift ⌘U) to select all of the clips that aren’t being used in the Edit Window. They will be highlighted in blue in the Clip List. Next, click on the dropdown arrow again and choose Clear (shortcut Shift ⌘B). A menu will pop up, giving us several options. Remove will unlink the clips from this session file: the files will still exist on the hard drive, but they will no longer be associated with this particular session file. Move to Trash will try to move the files into the computer’s Trash folder: you will have to manually empty the trash to delete these. Delete will permanently remove these selected clips from the hard drive: they will be destroyed.
So which one do we pick? Only Delete clips when you are absolutely certain that you will not need to recover any of them. This is a good way to clear up wasted space, but use it carefully. If we plan on sending this session off to someone else for mixing or additional recording, we may want to Clear the unused clips, and then create a new copy of the current session using the File > Save Copy In command. With this option, we can save a copy of this session along with all of the relevant audio & MIDI clips into a new folder. We can then send this copy off to someone else, or delete the original session. Whatever you do, choose carefully: you can’t go back.