Audio Performance Tips and Troubleshooting

On OS 9, if the sound is really choppy, the most common reason is you are outputting to two different audio devices. To remedy this, use the change ports dialog to change all audio ports to the same device as specified in the digital audio setup dialog.

Other common problems can be remedied by setting buffer sizes properly. Buffer sizes can be changed in both the Digital Audio Setup advanced dialog and in the Buffers Pane of the preferences dialog.

Audio files are usually large and can easily cause playback and/or recording problems for many computers. Problems occur most frequently when you try to monitor already-recorded audio tracks while you record new ones. Your computer tries to both read and write large amounts of data at the same time. Two solutions you should try before any others are:

Archiving any tracks you don’t need to hear during recording (see below)
Mixing tracks you need to hear during recording down to one stereo track to create a monitoring track (see below)

Note: Muting a track does not improve audio performance because your computer still has to process that track during playback. To archive tracks:

In the Tracks window, click the name of an audio track you want to archive. Command-click the names of any other audio tracks you want to archive.
From the Edit menu, choose Archive Tracks > Archive. The track names become grayed-out and Metro ignores the tracks during playback.

To unarchive tracks:

Select the tracks you want to unarchive.
From the Edit menu, choose Archive Tracks > Unarchive.

To mix a monitoring track:

Command-click the names of the audio tracks you need to hear during recording.
From the File menu, choose Mix Audio Tracks > To Track.

Metro mixes a new track from the tracks you selected and adds the extension Mix.AIF. Now you can archive all audio tracks except the monitoring track.

Audio Playback Troubleshooting Guide Possible Cause
Remedy
Too many audio tracks
Mix a monitor track and archive all other audio tracks
Too many clocks per quarter note
Reduce clocks per quarter note setting (Setup > MIDI Setup)
Too many tracks on a disk
Export some audio tracks to a different disk, if possible (not just to a new disk partition)
Buffer size too big or too small
Increase or decrease number in For Playback Allocate field (File > Preferences > Buffers)
Too many audio regions in a track. Metro creates a new audio region when you use an audio edit command or effect from the Edit menu.
View audio regions by turning on Show Audio Regions in the Switches menu (Metro dislays audio regions inside a red rectangle in the Graphic Editor). If a track has numerous audio regions, select it and use the File > Export Audio Track command, and check Replace source track with exported audio.
CD or DVD in driveIn some cases having a CD in the drive will slow down the entire OS. Eject the CD or DVD. Too much disk activityIn finder preferences, turn off all 'languages for searching for file contents'.

Problems with recording stem from the same causes as playback, with the exception of buffer size. Increasing the number of buffers instead of the size can sometimes improve recording performance.

In addition, there are several steps you can take to optimize your hard disk(s) for audio performance:

Disk Optimization Guide
Disk Problem
Remedy
Disk is fragmented, increasing seek time
Run a utility to defragment your diisk
Disk operation slowed down by unnecessary instructions
In the Finder, choose View > View Options > and uncheck Calculate folder sizes
Disk operation slowed down by unnecessary instructions
When you format a disk for recording, you may have the option to choose the Extended setting that supports small file sizes. Don’t choose this option—choose the Standard setting.

Audio Performance Tips and Troubleshooting