THIS MONTH

KeyboardMag.com >> This Month >> Follow The Bouncing Track

Images

This tip from the days of four-track recorders is handy even in the age of unlimited track co

Follow the Bouncing Track

By Craig Anderton

In the days of four-track tape recorders, one of the tricks that made decent multitracking possible was bouncing, where you’d mix three of the tracks down into the fourth. You could then erase the three original tracks, and record three more in their place. Noise? Distortion? Yeah, but it was all we had.

Bouncing’s legacy lives on in track “freezing,” which essentially bounces the audio from a soft synth into a hard disk audio track instead of playing back directly from the instrument. This saves CPU power because it takes less juice to play a hard disk track than perform a zillion real-time calculations to approximate the sound of, say, a vintage Minimoog.

But bouncing has other uses, too — and that’s why we’re here.

HOW TO BOUNCE

Hard disk recording programs implement bouncing in different ways, but the basic principle is the same. Note that if the track being bounced includes plug-in processors, their sound will be part of the bounce unless you can specify otherwise; and if you bounce multiple tracks, they’ll mix together.

Mute any track or bus that’s not supposed to be bounced. Note: If you’re “bouncing” a soft synth track to turn it into audio, make sure the MIDI track driving the soft synth and the soft synth audio output are both enabled.

1. Select the section you want to bounce. Generally, the more you’ve selected to bounce, the more time it takes to calculate and execute the bounce. There’s no need to bounce the entire track if you need to bounce only a section.

2. Play back what you’ve selected and observe the track’s meters (or bus meters, if that’s where the bounce is coming from). Check that there’s no clipping; otherwise, trim levels as necessary prior to bouncing.

3. Read your manual to determine the available bounce functions. Generally, you’ll have two options: Bouncing creates a new hard disk audio track, or it exports the track to an audio file, which you can then import into the program.

4. Initiate the bounce.

5. Play back the bounced track to make sure there aren’t any glitches, overloads, etc.

OKAY, NOW WHAT?

Now that you know how to bounce, here are some applications.

Signal processor mix. You have a great soft synth track, followed by a way cool plug-in effect. But you’re not sure where you’re going to bring the effect in and out during the final mix, so you can’t freeze the soft synth/processor combination until you automate the processor’s mix level.

Bouncing provides the workaround. Set the soft synth track’s processor to effected sound only (Figure 1). Bounce it, then bypass the processor. You now have two tracks: the soft synth with the bypassed processor, and an audio track with only the processed soft synth sound.

Freeze the soft synth track (remember, keep the signal processor bypassed). When it’s time to mix, use automation to vary the level of the bounced, processed track. Not only is the soft synth track frozen to save CPU power, but the signal processor isn’t sucking cycles, either.

The “backwards tape” effect. To resurrect this classic effect, duplicate the track to which you want to add reverse processing, then reverse this copy (look for reverse under a program’s DSP menu). Next, bounce the reversed track through reverb (no dry sound, only processed) to another track. Delete the copied/reversed track; it’s not needed any more. Finally, reverse the reverb track that was bounced. And get creative with the reverb track — pitch shift it, slide it forward or backward in time to line up correctly (or incorrectly), and so on.

Creating a stereo master. Bounce everything down to two tracks, and voilà — there’s your final mix. So why not just export to an AIFF or WAV file? You can, and eventually will. But there’s an advantage to this approach. Suppose you listen back to the track, and decide the piano needs to come up a tiny bit in one section. Rather than start over from scratch or mess with automation, just set the piano level as desired, select the region where you want the piano to change, set up punch recording, and bounce just that section into the track with the final mix. The splice points should be sample-accurate, so you should hear no click or transition as the old mix transitions into or out of the new section, unless level changes occur in the middle of a note.

Jargon Jockey

DSP Menu: DSP stands for “Digital Signal Processing.” In a sequencer or waveform editor, a DSP operation actually alters a file, so it’s called a “destructive” edit because it destroys the original version. (Personally, I’d find “constructive” edit a lot more cheerful — after all, it’s constructing a new file!) Typical DSP operations include track reverse, gain change, normalize, remove silence, etc. Destructive editing operations contrast with non-destructive operations like cut and paste, which don’t actually change the original file — they just “point” to different sections of the file for playback.

The Backwards Tape Effect: This gets its name because back in the ’60s and ’70s, engineers would flip tape reels over to play audio in reverse (or to create masked Satanic messages, take your pick). Jimi Hendrix, the Beatles, the Byrds, and many others used this technique. Sometimes they’d take this further by feeding a track playing back in reverse through something like reverb, recording the reverb into an open track, then re-flipping the reels. Thus the audio would sound as it did originally, but the reverb would sound “backwards” — instead of a note decaying into nothing, the reverb sound would rise from nothing to full strength, ending in the note that triggered it in the first place.