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System Overload Message

There are several solutions given in the online help. Here are some more:

Turn Off Unused Effect Options

This is a very easy way to save some processor bandwidth. Many real instrument presets, including even the default "No Effects" instrument, include effects options that are turned on but have their sliders set to a setting that creates no change to the sound. An example is echo with the slider set to 0, or equalizer with Bass, Mid and Treble all set to Neutral. Find any of these (using the Track Info inspector) and turn them off.

You can also turn off the Echo and Reverb in the Master track if you aren't using them.

Delete Silent Parts of Real Instrument Tracks

If your arrangement is complex and involves multiple real-instrument (live-recorded) tracks, then there is a good chance your tracks will have silent portions. For example, the vocals are usually silent during instrumental bridges, and some instruments are silent during the verses, or on one verse or another. These portions of the sampled audio can be deleted. Any deleted portions will give the processor less work to do during that portion of the song. Select the track, open the track editor (command-E in the Control menu), select the silent portion and hit delete.

Export and Reimport a Mixdown Track

Usually, you'll have a few tracks that are already "done" — no more editing is needed — or at least, not until you've laid down the other new tracks and are ready for the final balance mix. Take these "done tracks" and export them to iTunes, then re-import the resulting AIFF file as a new track. The new AIFF track will take far less processing power to play than the original software and real instrument tracks did. Here is the complete procedure:

- Identify which tracks are ready to mix down. These are the tracks that you aren't likely to change anytime soon. Mute (turn off) any tracks you don't want to mix-down.
- Export to iTunes.
- Rename the track in iTunes (I call it something like "Mixdown Tracks 01-02-03-05-07"). Do not convert to MP3 (GarageBand will reconvert into AIFF anyway.)
- Select the track it the iTunes window and drag it into the GarageBand window; it will import back into your project.
- Use the Track Info inspector to turn off the track's echo and reverb settings (which are always enabled by default, but set to zero — see previous hint).
- Mute (turn off) the tracks you just mixed down, and turn the other tracks back on.

Later, when you are ready to do your final mixdown, mute the mixdown track and re-enable the original tracks. You can make any final adjustments to volumes, effects, etc. and then export all your tracks. Of course, you can create a new partial mixdown if there were problems in the first mixdown, or when you reach your CPU limit again and need to add even more tracks.

If the number of tracks in the window gets to be unwieldy, or if you want to speed things up a little more by eliminating the need for GarageBand to draw and scroll the muted tracks, you might choose to create a new GarageBand project that uses just the mixdown plus any newer tracks. Of course, you have to set the key, time signature and tempo to be the same as in your original project.

Reduce the Drawing

I have heard several suggestions that all amount to reducing the amount of time the program needs to spend on graphics (drawing). I have not yet verified that they work. The suggestions include: Hide Track Mixer (in the Track menu, or command-Y); Hide Editor (in Control menu, or command-E); change monitor depth to 16-bit (thousands of colors); hide GarageBand completely (in GarageBand menu, or command-H). That last one might sound pointless, or useless if you're trying to record a new track, but you can start playback (or record) then hide it before things start to get really intense.

Change Instruments Temporatily

Some software instruments take more processor power than others. I have not yet evaluated this in detail, but the basic idea is to switch to some other instrument that requires less processor power, then at some later point (like when your're ready to mix down) switch it back.

Store Project File on Another Drive

This might help if you have another hard drive that is faster than the one currently holding the project. "Faster" could mean RPM rate, seek time or data transfer rate. The reason this matters is that GarageBand has to periodically load in parts of your real instrument tracks while it is playing (because there is not enough memory to keep them all loaded all the time). This is another suggestion I have not yet verified.

Delay Bugs

I have experienced a couple repeating problems with GarageBand's output delaying behind the input (when playing live (real instrument selected, live monitor turned on). Sometimes it happens as soon as you launch the app (hardware-related causes, or hardware-related settings, see below) and sometimes it starts happening after a period of playing properly "in sync".

In this latter case, the bug seems to be in GarageBand itself, or perhaps the OS (I say this because it can happen if you launch something big like iTunes while GarageBand is running). This bug is fixed by getting GarageBand to play the track for a second or two, and then stop (in other words, hit the spacebar twice.) This seems to fix the problem by making the application or the audio driver clear (flush) its sound output buffer.

Other Usage Notes

You can move tracks left or right to fix synchronization problems (which often happen when you lay down live tracks alongside existing tracks, and happens because of buffering delays between the input and output.) Normally you can only adjust these in multiples of a quarter-note. To adjust more precisely, turn off "Snap to Grid" in the "Control" menu.

Live Performance Issues

If you're new to live recording, you might encounter a few of these simple issues:

Hum in the Guitar Input

The computer interface seems to add hum (or maybe the hum comes from the computer and the guitar is too close to the computer). At any rate, I have found that the hum is all coming from the guitar pickups. It is not heard in all guitar settings — for example Clean Jazz has no hum, and Modern Rock has a lot. Most of the hum can be cancelled out by using the hum-canceling settings on your guitar pickup switch. If you have a 3-pickup guitar, your pickup switch will have 5 positions — use position 2 or 4. On a 2-pickup guitar you have three positions and you should use the center position.

Delay in Monitor Headphones/Speakers

You may find that the monitor or your headphones delays a bit behind your singing or instrument playing. Depending on your audio hardware, this is fixed in different ways. Some examples:

If you are using a USB audio interface through a USB hub, there will probably be a delay added by the hub. Connect the audio interface to a direct USB port on your computer.

For a similar reason, you might have better results on certain Mac models (like older iBooks) if you disconnect other USB devices (like a mouse) because both USB ports share the same USB controller chip inside the computer.

Some USB audio interfaces provide direct input monitoring, which directs the input signal to the device's output. Switching this on lets you hear your voice or instrument instantly. This solves the very important problem of keeping time with yourself. However, if you are adding a track to an existing project, you'll still have to deal with any delay in the audio output. Because of a delayed output, you're actually playing a bit behind the other track(s) even though it doesn't sound that way to you when you're recording the track. You'll hear the delay when you play back the result. To fix this you either have to fix it each time by shifting the newly-recorded track back in time, or find a way to reduce the output buffering delay.

See also the "Delay Bugs" section above.

Edirol UA-20 Notes

This is a great combination audio and MIDI interface, but the documentation is a bit lacking and most settings options don't work with GarageBand. I eventually got it to work by following these steps:

- If running GarageBand, quit. Also, quit any other applications that use sound output (like QuickTime Player).
- Set the "Advanced Driver" switch on the Edirol UA-20 to "ON". Disconnect, and then reconnect the Edirol UA-20.
- Go into System Preferences, choose "Audio". Set both Input and Output to use the Edirol UA-20.
- Select the Edirol UA-20 panel. Click Restore Defaults, then Apply.
- Quit System Preferences (or just select "Show All" or another Prefs panel)
- Start up GarageBand. Open your project or create a new one.
- In GarageBand's preferences, set Audio input and output to use the Edirol UA-20.
- Wait a couple seconds, and you should hear the sound coming out the Edirol's output.
- When switching instruments, there will sometimes be a delay of a couple seconds, or some silence.

Specific problems and issues are described below:

Input Hiccups, Noise, Dropouts

There is a bug in the input driver that causes this to happen when the input line level gets too high. The solution is to turn the input gain (the main knob on the UA-20) down to about 1 or 2. This of course makes the input audio level very low; you compensate for this by raising the input gain in GarageBand, raising the master volume, raising the MacOS output volume level, etc..

Advanced Driver Switch

In order to change this setting, you need to disconnect and reconnect the UA-20 after flipping the switch. That means you also have to quit GarageBand first, and after restarting GarageBand you have to reset the audio input and output devices in GarageBand's Preferences.

If you set this to "off", the Edirol driver doesn't load, and the default MacOS USB-audio driver takes over access to the device. The Edirol UA-20 System Prefs pane will report that it cannot find the device, and GarageBand reports that there is no MIDI interface. GarageBand works pretty well, but without MIDI it kind of defeats the purpose of getting the Edirol UA-20 in the first place.

If the switch is "on", the Edirol driver installs itself and is recognized as a MIDI interface by GarageBand.

"Device Could Not Be Found" Message in System Preferences

This message appears when you enter the UA-20 pane of System Preferences when the UA-20 is in OS-native driver mode (see above paragraph on "Advanced Driver Switch").

Settings in System Preferences

Here I refer to the settings in the Edirol UA-20 pane, which are only relevant if you have the "Advanced Driver" switch turned on (see above). I have gotten it work work using the default settings, and have had problems when I tried to set the buffer size to minimum and the other two to 0. The buffer size setting is important — the larger the buffer, the higher the delay between your instrument and the accompaniment when laying down a live track. If you set it all the way to minimum, there is no sound — I suppose there are buffer underrun problems and it just shuts down.

(Regarding the "Audio" pane in System Preferences, it appears you can set this however you want, but GarageBand will use its own settings (in its own Preferences window). This means you can have your other apps (I tried QuickTime Player and iTunes, which both worked) playing their sound through the computer's built-in audio and GarageBand playing through USB audio out simultaneously, giving you the ability, in theory, to play 4-channel (quadrophonic) music arrangements — although I don't know how you'd get them synchronized, apart from deftly hitting the space bar at the right instant.)

Input Sound Starts Looping

I only got this problem when using MacOS X's built-in USB audio driver ("Advanced Driver" switch set to "off"). The symptom acts like your input is a broken vinyl record — it repeats a snippet of sound about 1 second long, over and over again. The problem is within the input driver — quitting and restarting GarageBand does not help, nor does switching the audio input to built-in audio and then back to the Edirol. To fix this, you have to quit GarageBand, disconnect the Edirol unit, reconnect it and restart GarageBand.


Here are some places you can go for more information:

MacJams, a general-purpose site for musicians with Macs, has a heavy focus on GarageBand and accessory products. You can search their site here.

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This page was written in the "embarrassingly readable" markup language RHTF, and was last updated on 2008 Apr 30. s.27