Adjusting the timing of a multi-track performance while maintaining phase relationships

Editing a multi-track instrument, such as a multi-microphone drum kit or a full band, requires a little more care than editing a solo performance.

When stretching or quantizing multi-track audio, it is critical to maintain the phase relationships of the original recording. This can only be achieved if the tracks are stretched at the same exact points in time across all tracks.

AudioSnap provides tools that make it easy to preserve the phase relationship across tracks when editing beats on individual tracks.

In the following example, you will learn how to use AudioSnap to edit a multi-track drum kit alongside a piano track. The drum kit was recorded with three microphones (kick, snare, and overhead), each routed to its own track.

To adjust the timing of a multi-track performance while maintaining phase relationships

The following figure shows the last three hits of a song. The top track is piano and the rest are drums: kick, snare and overhead.

Figure 230. The drum hits are rushed and are not in sync with the Piano track

A. Piano track B. Drum tracks

As you can see, the drummer has rushed and is not in time with the piano. At the beginning of the measure, the drummer is in time with the piano. Over the course of the measure, the drummer is performing a fill and on the next three beats is way ahead of the piano player. You can see how the transient markers on the drum tracks are progressively earlier as the measure goes on (the drummer is rushing).

Our job is to align the drum hits with the piano hits so that the drum and piano tracks in time all the way through the measure.

1.	Select the Smart tool in the Control Bar.

2.	Assign the track’s Edit Filter control to Audio Transients.

Audio clips display transient markers and the AudioSnap palette appears.

3.	Select the three drum tracks and make splits right before and right after the area you want to edit. For details, see To split clips into smaller clips.

4.	Select only the kick and snare clips.

5.	On the AudioSnap palette, set Resolution to 1/16.

6.	Select only the drum overhead track.

7.

On the AudioSnap palette, set Threshold to 100% to ensure that there are no transients detected. This step is necessary because the overhead track contains audio from both the kick and the snare, and you want to make sure the kick, snare and overhead tracks are always synchronized when stretching beats.

8.	Select all three drum tracks.

9.	Right-click any selected clip and select Merge and Lock Markers on the pop-up menu.

All three drum tracks now share the exact same transient markers, and each clip’s position is locked.

Note: When you fix timing errors in multi-tracked drum parts, you typically need to adjust all the drum parts in exactly the same way, because drum parts often contain “bleed”—the sound of other drums in the track of the drum that you are trying to record. For example, if your snare mic also picks up some of the hi-hat sound, you can’t move hi-hat clips around without also moving the snare clips in exactly the same way, otherwise the sound of the hi-hat in the hi-hat track will conflict with the sound of the hi-hat in the snare track. Any time you have a track that contains “bleed” from other audio tracks, such as drum overhead tracks or room ambiance tracks, you want to make sure the track has the same identical transient markers as the individual close-mic tracks. The first step is to disable all transient markers in the overhead/room track, then use the Merge and Lock Markers command to copy the transient markers from all individual close-mic tracks.

Figure 231. The Merge and Lock Markers command has copied the same transient markers to all three drum tracks.

The drum tracks are now ready to be edited.

We want to keep the feel of the piano track, so our goal is align the drum tracks with the piano track, while preserving the phase relationship between the three drum tracks.

When editing multiple transients to adjust the timing of a performance, often times you need to speed up or slow down a section rather than just move an entire section later or earlier. In this example, the drummer was speeding up through the drum fill and then hits next downbeat too early. To fix this, you need to proportionally drag the drum transients so they are better aligned with the piano track.

10.	Using the Smart tool, lasso select all transient markers from the first hit through the third hit, across all drum tracks.

11.	Hold down the CTRL key and drag any selected drum transient marker until the third drum hit is aligned with the third piano hits.

The selected transients are stretched proportionally. The first and last drum and piano hits are now aligned. The effect of this edit is that the drummer no longer rushes through the fill and he lands on the downbeat much closer with the piano.

Figure 232. The drum and piano hits are aligned

The second drum and piano hits are close but not perfect, so we need to fix this single beat.

12.	Hold down the CTRL key and double-click any drum transient marker on the second hit.

All drum transient markers for the second hit are selected

13.	Drag any selected transient markers until it aligns with the second piano hit.

All three drum and piano hits are now aligned properly, and the phase relationships between all drum tracks have been preserved.

Figure 233. All three drum and piano hits are perfectly aligned

For information about maintaining phase relationships without stretching audio, see To quantize multi-tracked drums without stretching audio.

 

See:

Adjusting the timing of a solo performance

Synchronizing the rhythms of out-of-sync tracks

Making multiple clips/tracks groove together

Quantizing audio

To quantize audio to the project’s time ruler

To Groove Quantize an audio clip

To quantize an audio clip to another audio clip (Quantize to Pool)