8 Groovy Tips for Beat Detective

Using Beat Detective to slice up a loop into a series of individual beats is so simple that one hardly need glance at the Pro Tools manual. But there's
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Using Beat Detective to slice up a loop into a series of individual beats is so simple that one hardly need glance at the Pro Tools manual. But there's more beneath the surface of Beat Detective than meets the eye. With a little of your own detective work, you'll see that slicing up loops is just one of the program's many tricks.

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FIGS. 1a and 1b: Here are several audio regions that have been edited using Beat Detective, with the groove from the Stereo Drums track (track 1) applied to all of the separated audio regions.

Combined with tick-based audio tracks, which were first introduced in Pro Tools 6.7, Beat Detective is like having Propellerhead ReCycle and a sampler built in to Pro Tools. Now, just like a MIDI event on a MIDI track, your separated audio regions that are on ticks-based audio tracks will retain their bar, beat, and tick positions — even when a session's tempo is changed. Beat Detective is consequently more useful than ever as a tool for loop-based production and remixing.

Originally, Beat Detective was only available in Pro Tools TDM. As of version 6.4, however, Beat Detective LE was added to Pro Tools LE (and is also a part of M-Audio Pro Tools M-Powered). The primary difference between the TDM and LE versions is that Beat Detective LE doesn't enable you to edit multiple audio regions at the same time, whereas the HTDM version of Beat Detective allows you to edit several selected audio regions simultaneously. If, however, you typically edit only one loop at a time, that difference will be relatively minor and you won't miss it if you are using Beat Detective LE.

Marking Your Beats

At times, Beat Detective does not catch a transient until you've pushed the Sensitivity control all the way up. If you're editing a simple waveform that has well-defined transients, the beat markers will be placed right where you want them. If, however, the waveform is complex, with lots of tiny, smeared transients, then you will end up with more beat markers than you need. In that case, when you slide the Sensitivity control back down again, the markers you do want will usually disappear, along with the erroneous markers.

Instead of painstakingly deleting the markers you don't want, lock down the markers you want to keep. That is called promoting a marker. Using the Grabber tool, Control + click (on the Mac, use Command + click) on the markers you want, and then slide the Sensitivity control down to 1 percent. Only the beat markers that you promoted will remain.

If pushing the Sensitivity control all the way up still doesn't catch a particular beat, you can drop a beat marker in manually with the Grabber tool by clicking in the selected audio region. You can also use the Grabber tool to slide the marker around and fine-tune its position.

If you have an HTDM system, you can use the Collection mode, in the Detection section, to collect beat markers from different audio regions to create a single, composite beat map. For example, you could collect beat markers from each track of a multitrack drum session, and then use the composite beat map to slice up all of the drum tracks at the same time.

Groove Extraction

An important production skill for making parts groove well, particularly when working with elements from disparate sources — such as found loops, step sequencers, and live performances recorded at different times — is the ability to create and apply custom groove-quantize templates. Beat Detective allows you to lift the groove from one performance, save it as a template, and then apply it to other performances, giving you complete control over the feel of each track.

After you've set the beat markers for an audio or a MIDI selection, switch to the Groove Template Extraction mode in Beat Detective's Operation section. You don't need to perform a region separation beforehand, because the groove template is based on the position of the beat markers themselves, rather than on audio region start times. When you press the Extract button, you can either save the template temporarily to the clipboard or archive the groove template to disk in the Pro Tools Grooves folder.

From the Region Conform mode, you can apply the groove template to a selected audio performance, as long as its beats have already been separated into individual regions. Select Groove as the Conform mode, choose your groove template from the Grooves menu, and then press the Conform button to quantize the start of each audio region to the nearest beat or sub-beat of your groove template (see Figs. 1a and 1b, and Web Clips 1a and 1b). To apply a groove template to a MIDI performance, you will need to use the MIDI Groove Quantize window. Any groove template created in Beat Detective will appear in the MIDI Grooves menu as well.

The Region Conform mode and the MIDI Groove Quantize window provide a Timing parameter for setting the strength of the groove template, which determines how strongly the selected events will be pulled toward the groove. That control is essential, because performances that are too tightly locked together can sound unnatural. By using the Timing control, you can play with different percentages of the groove across different tracks to create a performance that pushes and pulls the beat just like a live jam.

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FIG. 2: This screen shot shows an example of a tempo map -generated by a live -percussion groove. The tempo for each 16thnote grid -division can be seen next to each tempo-change marker.

Tempo Map to Grid

A live performance that isn't recorded to a click track won't have beats that line up neatly to the grid in Grid mode. As a result, editing and MIDI sequencing is more difficult. No matter how carefully you nudge the audio region into sync with the grid and adjust the session's master tempo, the variations in tempo will cause the track to drift out of time. The solution: don't try to make the performance line up to the grid; instead, use Beat Detective to make the grid line up to the performance.

With Beat Detective, you can generate a tempo map based on the position of the beat markers (see Fig. 2). First, set your beat markers in the Bar|Beat Marker Generation mode, and then press the Generate button to deploy a series of Tempo Change markers in the Tempo Ruler. The grid will follow the tempo changes, with each bar and beat division tied to the bars and beats of the live performance. With the grid all lined up, on-beat edits are easy and MIDI events can be snapped to the grid for sequences that are perfectly in time.

Smooth Edits

After slicing up a loop and then changing the session's tempo, you may hear pops and clicks between some of the audio regions. That occurs when a region's waveform isn't separated at its zero-crossing point (the point where the waveform crosses the x-axis.)

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FIG. 3: After a Fill and Crossfade operation, you can see the crossfades between each region and the sync point for each beat within the regions.

In Edit Smoothing mode, there are two ways of silencing those annoying pops and clicks: Fill Gaps and Fill and Crossfade. Fill Gaps extends a region's leading edge to meet the ending edge of the region directly in front. That option can work well when there is silence between the beats, because in extending a region's edge, you'll probably land on a zero-crossing point. When there's a lot of audio between the beats, however, landing on a zero-crossing point is unlikely, and you'll need to use a crossfade to smooth out the transition between the regions. Fortunately, the Fill and Crossfade option can perform the fill, and then automatically crossfade the regions in one step (see Fig. 3). Fill and Crossfade usually works like a charm (see Web Clips 2a and 2b).

Both Edit Smoothing options offer a bonus — a sync point at the beginning of each beat. Because the fill process extends a region's edge in front of the beat, the sync point now acts as a marker for the actual start of the beat instead of the region's leading edge. Consequently, an audio region with a sync point will snap to the grid at its sync point rather than its leading edge. Even quantize and groove quantize will pull a region by its sync point. That makes rearranging beats in Grid mode an absolute joy, enabling you to cook up breakbeat and drum-and-bass style grooves in no time.

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FIG. 4: From the pop-up menu next to a track''s name, you can create and recall duplicate versions of the track.

Consolidate Your Regions

After separating and crossfading lots of regions, you can end up with a processor-intensive session because of all your edits. To ease the burden on your CPU and hard drive, use the Consolidate Selection command to merge groups of separated regions into new contiguous audio regions.

To make sure that you don't lose any of your edits, create a duplicate track by clicking on the arrows next to the track name in the Edit window and choosing Duplicate. Next, consolidate the regions on the copy (see Fig. 4). Leave the original track hidden, beneath the duplicate track, in case you need to adjust any of its regions (that is, to nudge a beat or shorten a crossfade).

Birth of the Groove

Beat Detective is easy to use and can be used in many ways. Its variety of functions will allow you to realize the hidden groove potential in almost every audio region in a Pro Tools session.

Erik Hawkins has written several books, the latest being The Complete Guide to Remixing: Produce Professional Dance-Floor Hits on Your Home Computer (Berklee Press, 2004).