Tuesday, August 20th, 2019

Quantising in Pro Tools using Beat Detective

By Nick LucasOctober 1, 2012


Nick Lucas
Nick started out producing Drum & Bass and other Dancefloor styles under the pseudonym Veranova, still a major part of what he does.  Nowadays though, he also does a lot of Freelance work: composing for companies such as Morphsuits and producing music for the likes of Lewis Mokler, and Pob.  His most recent venture however, is Production Bytes, a web tutorials series aimed at Beginner & Intermediate level producers, which has led him straight into his passion for teaching and writing.

Following on from my article on audio Warping in Pro Tools last month (read here), the next related subject would be Beat Detective.  As I mentioned in the last article, Warping is great when you have an instrument that will sound most natural with a flowing release curb.

However, what if you have an instrument (such as Drums) where the transient is more important than the release, and extending or shortening the attack or release phases could have a big impact on the realism of the recording?

This is where Beat Detective comes in.

Beat Detective is a very powerful tool for pulling lots of types of audio into time, however I’m going to focus today on how to quantise drums with it; which is what it’s most well known for.  Beat Detective works by first detecting transients in audio, then allowing you to chop the audio up at these points and finally Quantise, or ‘Conform’, the newly created audio ‘Clips’ to the grid.  Bear in mind you will need to have recorded your drums to a Grid/Click in order for this to work, as Pro Tools conforms audio based on its grid.

First of all here’s the initial drums project i’ve got:

https://www.audio-times.com/audio/NL1-Initial Drums_011012.mp3

You can hear that the drums are quite sloppy against the click track, so today we’re going to move these drums onto the grid.  The first thing to do when you have multi-track Drums which you want to Quantise using Beat Detective, is group all the audio tracks as an ‘Edit Group’.

Select all the audio tracks in question and press Ctrl+G [Cmd+G on Mac], then select ‘Edit’ under ‘Type’.

This locks all the audio together, so any changes you make to one track will also be made to all other grouped tracks. With Multi-track/Multi-mic recordings this is important to keep the phase of all audio the same, and avoid phase interference or flam effects.

Now you’re ready to start using Beat Detective.  Select the audio you want to quantise, and go to Event>Beat Detective; or press Ctrl+8 (8 on the Numpad) [Cmd+8 on Mac].

You’ll now be presented with the Beat Detective window.  On the left you have the ‘Operation:’ area with 5 tabs, start in the ‘Bar | Beat Marker Generation’ tab.  Under the selection area, hit ‘Capture Selection’ to make sure the selected audio is seen by Beat Detective. You’ll also need to tell Beat Detective what time-signature the drums are, and what the smallest note the audio contains is. In this case it’s 4/4 time and 1/16th notes, but selecting larger note sizes (1/4 note for instance) will allow you to be less picky with the processing; and retain some of the natural timing by only Quantising the ‘on beat’ transients.

Now that you’ve set up the selection, look at the ‘Detection’ section.  To detect the transients you just have to hit ‘Analyze’, and then drag the sensitivity slider up until all the transients you want have been detected. You will probably want to set ‘Resolution’ to ‘Sub-Beats’ as this allows much finer detection than the other settings, but this stage usually requires some fiddling to detect everything you want.

The ‘Analysis’ menu simply provides some different detection algorithms.

‘Low Emphasis’ looks predominantly at low frequencies, ‘High Emphasis’ looks at high frequencies, and Enhanced Resolution is a more advanced algorithm that most of the time is the best way to go, especially with complex audio material.

Once you’re happy you’ve accurately detected as many of the transients as you need, move to the ‘Clip Separation’ tab; and hit ‘Separate’ in the bottom right hand corner.  This will use the markers you just generated to chop the audio up in a series of clips.

Now move to the ‘Clip Conform’ tab.  This is where the audio clips you just created are Quantised to the grid.  Under the ‘Conform’ area, set up your Quantisation options.  To Quantise perfectly to the grid, simply set ‘Strength’ to 100% and then hit ‘Conform’ in the bottom right. You might not want to completely perfect the timing, so just slack off this option if you just want to nudge the Clips closer to the Grid.  The other options are more advanced and useful when trying to create a new groove, but are beyond the scope of tightening up the performance.

This is the first point in this process where the Audio will have been changed, and there will be some spaces with no audio, and some overlaps too. This isn’t a particularly natural sound, but we’ll work on that in a moment.

The drums after conforming, but without any smoothing or manual correction.

https://www.audio-times.com/audio/NL2-Conformed Drums_011012.mp3

At this stage you should have a listen to the drums against your click track. If the rhythm is completely straight and the timing wasn’t more than half the ‘Selection’ resolution out of time at any point, it should be perfectly quantised.  But you may find some errors so listen through and if necessary nudge individual clips into time manually.  In the case of these drums there’s a kick fill halfway through which is meant to be in Triplets time, so with my edit window set to ‘Grid’ mode, and my grid set to ‘1/16th Triplets’ i’m just going to grab the clips from that fill and bump them into the right timing.

Before manually correcting the timing

https://www.audio-times.com/audio/NL3-conformed triplets before_011012.mp3

After manually correcting the timing

https://www.audio-times.com/audio/NL4-conformed triplets aftwe_011012.mp3

So here is the final conformed audio.

https://www.audio-times.com/audio/NL5-final conformed_011012.mp3

The next stage is to neaten this up and make it sound more natural.

Select the audio again, and go back into Beat Detective (Ctrl+8 / Cmd+8).  Now move to the ‘Edit Smoothing’ tab, and under ‘Smoothing’ select Fill And Crossfade.  The default crossfade length should be fine, but have a fiddle around if you get any clicks or chorusing at the crossfade points.  To apply the Smoothing, select ‘Smooth’ in the bottom right.

The Drum Track should now be perfectly in time, and sound natural again thanks to Beat Detectives Smoothing function.


Below is the final Audio for the drum track, and also the Pro Tools project so you can have a play yourself.


Audio Times Beat Detective Example (9.2MB zip file)

Also many thanks to Phil Jackson for providing the Drums Project and allowing me to distribute it.


Nick Lucas
October 2012

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