K403/K503 Assignment 5: Digital Performer Audio I

• Importing CD audio
• Soundbites window
• Sequence window
• Edge edit and fades
• Create volume and pan data by drawing

Ripping Audio From a CD

First, we'll capture some audio from a CD and import it into a Digital Performer project. This capturing process, known as ripping, is a digital transfer of samples from the CD to a sound file on the hard disk.

NOTE: Do not include copyrighted recordings in a piece of your own without written permission from the copyright holder! Otherwise, you may be exposing yourself to legal action in the future. Note that some of the sound effect CDs we have do not seem to give such permission. (Then what good are they?!)

1. Grab a few sound effect CDs from the closet in room 302.

   Be sure to put these back when you're done!

2. Insert an audio CD into the Mac's CD drive. Drag a track icon from the CD onto the Desktop. This extracts the audio for that track into a new interleaved stereo sound file on the hard disk.

   Remember that 1 minute of stereo CD-quality audio takes about 10 MB of storage space. If you want a smaller segment of a track, trim it in Peak. (You can also extract CD audio using Peak, which lets you extract only part of a track.)

Grabbing Audio From the Internet

SoundSnap

Browse the sounds — you can play them to find out which ones you like — and then download them as AIFF or WAV files. (Try to avoid MP3 files, if possible.) These sounds are all free to use.

Here is a list of other sound sites.

Of course, you can also play with any of the sounds you recorded in Assignments 1 and 2.

Next we'll import our audio into a new Digital Performer sequence.

Placing a Sound File into a Track

1. Launch Digital Performer, and create a new project.
2. A new sequence file already has some empty audio tracks. The tracks are either stereo (for 2-channel audio) or mono. The number of squiggles next to the track name tells you which (1 for mono, 2 for stereo).

   

   You can use stereo soundbites only in stereo audio tracks, and mono soundbites only in mono audio tracks. Files ripped from CDs are stereo.

   If you need more tracks, create them by choosing Mono Audio Track or Stereo Audio Track from the Project > Add Track menu.

3. The easiest way to get a sound file into your project is to drag it from the Desktop into an appropriate audio track.

   

   When you see the light blue rectange, release the mouse button to drop the file into that track. Digital Performer won't let you drag a stereo sound file into a mono track, or vice versa, and it won't let you drag a sound file into a MIDI track. The imported audio file appears in the track as a new soundbite; the soundbite refers to the entire duration of the audio file you imported.

   When you import sound files, Digital Performer automatically copies them into the Audio Files folder inside of your project folder. If a file is stereo, DP de-interleaves the file — making a pair of "split stereo" files, one for each channel — and uses these instead of the original interleaved file.

4. Now you can drag the soundbite around in the track, as if it were a MIDI note. You can create other instances of the same soundbite by option-dragging it (i.e., holding down the option key while dragging).
5. Once in your sequence, the soundbite appears in the SoundBites window, which you can open by typing shift-B. As you edit soundbites, Digital Performer will create more entries in the soundbites list. You can place an instance of a soundbite into a track by dragging its move handle (the squiggly shape in the MVE column of the Soundbites window) into a track.

   

   In the Soundbites window, you can click on a soundbite name to hear the soundbite. (If this doesn't work, click on the speaker icon in the window's title bar so that it turns yellow.)

   CAUTION: If you double-click on the soundbite name, instead of single-click, then you'll open a destructive audio-editing window. You don't want to do anything destructive now, do you? Close that window before it's too late.

Project Folder Organization

A project folder contains a sequence file, as well as folders for sound files and other things. Sound files are much larger than MIDI files. Because a project contains multiple files and folders, you need to be especially careful about backing up. My recommendation is to keep everything relevant to the project inside your project folder, and copy this folder to and from the CECM Server for backup. Keep an extra copy on a USB flash drive or portable hard drive.

NOTE NOTE NOTE
You should not run your project directly from the CECM Server. Even though this may work some of the time, it's usually too slow to be reliable, and you will certainly not be able to record reliably to the server. You might hear audio drop-outs, or Digital Performer might complain about not being able to run all the audio effects you want. Never try to run a project directly from a CD or USB flash drive, which are too slow.

To reduce the chance that Digital Performer will use a sound file on the CECM Server or your CD or USB drive instead of one on the hard disk, eject all servers and other disks before opening your sequence file.

Soundbites — What are they?

Here's the important part: the soundbite does not contain a copy of the portion of the sound file. In other words, the soundbite does not contain audio samples copied from the sound file. It just contains two references — start time and end time — to the sample data in that file. This means that the soundbite doesn't take up very much memory or disk space — nowhere near the amount used by the audio data. It also means that editing soundbites is very fast, because only the start-time and end-time references must change, not the actual audio data in the sound file. Soundbites are the cornerstone of Digital Performer's non-destructive editing environment: they make it possible for you to cut and paste bits of audio without ever altering the original sound file.

NOTE: Soundbite is a Digital Performer term. The same thing is called a region in Pro Tools and some other software.

Editing with Soundbites

You can hide and show audio tracks in the Sequence Editor window in the same way that you do this in the Mixing Board window: by clicking on track names at the left of the window. When you first open the Sequence Editor window, though, it won't show this list of track names. To see them, click the box icon in the title bar.

Here are some of the more common editing techniques.

• Drag a soundbite to move it to another place in the same track or to move it to a different track, just as if it were a MIDI note. Pay attention to the Edit Resolution controls in the upper right part of the window.
• Option-drag a soundbite to place a copy of it in another track or at another time in the same track.

  CAUTION: Click in the waveform part of the soundbite, not in the colored title bar above the waveform, when you have the option key down. If you option-click the title bar, you'll be asking to change the name of the soundbite.

• Control-drag a soundbite to make it snap to the edge of another soundbite.
• Option-control-drag a soundbite to copy it and snap the copy to the edge of another soundbite. This is a way to make repetitive patterns.
• Double-click a soundbite waveform, and then drag across the waveform to select just a part of it. After you drag, you'll hear the segment you selected (as long as the speaker icon in the window title bar is lit up yellow — see the previous graphic). Then you can cut or copy the selection and paste it elsewhere, using commands in the Edit menu. Before pasting, click with the cross-hair cursor somewhere in the empty space of an audio track. Digital Performer generates new soundbites as needed.
• Use the Split command (Edit menu) to break one soundbite into three separate soundbites. Double-click a soundbite, select part of it, then use the Split command.
• You can change the dimensions of a soundbite by edge-editing. This means dragging the left or right boundary of a soundbite to reveal or exclude some of the underlying audio file. Move your mouse over the left (or right) edge of a soundbite — over the waveform part of the soundbite, not over its colored title bar. Your cursor changes to the edge-edit cursor.

  

  Now click and drag. This changes the start (or end) time of the soundbite, relative to the start of its sound file.

  NOTE: When edge-editing, don't drag the edge near the top of the soundbite, since that time-stretches the soundbite instead.

  What happens after you edge-edit depends on the state of the Edge Edit Copy item in the mini-menu. (That's the little icon just to the right of the close icon in the window title bar.)

  

  • If it's checked, then dragging a soundbite boundary creates a new soundbite with the new time range, leaving the original soundbite definition alone. (Think: edge-editing copies the soundbite.)
  • If it's not checked, then the time range of the soundbite is redefined. Since this affects all other instances of the soundbite in all tracks, you need to be careful with this setting, lest you redefine soundbites that you can't see in the current view.
  Both settings have their place, so you should become very familiar with them. (You can toggle between them quickly by holding down the option key while you edge-edit.)

Volume and Pan Automation

1. Open the Sequence Editor. At the left of each track is a control panel. A pop-up menu lets you select different editing modes. Normally you'll see Soundbites here. This mode lets you drag your soundbites around and edit them.

   

2. Choose Volume from this pop-up menu. Now any soundbites in the track are dimmed, and you can use the pencil tool to draw a volume line. (If you don't see the Tool palette, choose Tools from the Studio menu.) The volume line works by "connecting the dots." You supply the dots, and the program draws lines between them to ramp the volume from one setting to another. Digital Performer calls one of these dots an audio volume event, which you can edit very precisely, as if it were a MIDI volume controller event.
3. The volume lines you've drawn may display as dotted lines. This means that automation is not play-enabled for that track. If you play the track, you won't hear any volume changes. You can play-enable automation using the Mixing Board window, as we did for MIDI tracks. Or you can use the handy Auto pop-up menu in the Sequence Editor control panel.

   

4. You can drag the dots around to change the shape of the volume line. Click on a dot and press the delete key to delete it.

The audio volume event values are expressed in decibels (dB). A value of 0 dB means the audio plays from the disk with no amplitude scaling. If you shape the line so that it goes above 0 dB, the audio samples will be multiplied by a factor greater than one, and you could easily cause clipping (digital distortion). If this happens, the track's meter in the Mixing Board window will show it.

Panning works similarly to volume:

1. Choose Pan from the same editing mode pop-up menu from which you chose Volume.
2. Shape the line just as you did for the volume line. To pan to the left channel, drag a dot to the top of the graph. To pan to the right channel, drag to the bottom. The vertical center of the graph corresponds to the center of the stereo field.

Choose Soundbites from the editing mode pop-up in order to edit soundbites again.

Shortcut: Hold the option key down while selecting an editing mode (e.g., Soundbites, Volume, Pan) from any audio track's popup menu: all tracks will change to that mode.

Fortunately, audio volume and pan is easier to handle than MIDI volume and pan, because you don't have to worry about inserting initial controller values, as you do for MIDI.

Preventing Audio Clicks

You get rid of clicks by applying a volume envelope to a soundbite. Even a very quick, barely noticeable attack or release can suppress a click. There are two ways to create these envelopes:

• Volume ramps, as described above — not really recommended for click suppression.
• Fades, created using the Fade command (Audio menu). To create a fade, select a brief time region overlapping the start or end of a soundbite, then invoke the Fade command. Make your selection in the Sequence Editor for precision. This method is preferable to the volume ramps, partly because the fades move with the soundbite when you drag it, but the volume events don't.

  There is a graphical shortcut to using the Fade command: move the mouse over the edge of a soundbite, in the area just between the waveform display and the colored title bar. When you see the crossfade cursor, click and drag toward the middle of the soundbite to create a fade (or crossfade).

  

This may strike you as an obscure consideration, and you can safely ignore it for this assignment. But to get professional results, you'll have to deal with the problem of clicks sooner or later — like in your final project!

Combining MIDI and Audio

Back up your project folder to the CECM server!

©2007, John Gibson, Christopher Cook