QLab Tested System Configurations

The following information describes known software conflicts that may affect QLab.

10.6, Snow Leopard

The Camera Cue in QLab 2.3 and later is compatible with OS 10.6.x.

The Camera Cue in QLab 2.0 through QLab 2.2.8 is NOT compatible with OS 10.6.x. Apple introduced a memory leak in the video input API for 10.6, which caused Camera Cues in these versions to eventually crash.

MP3 playback in QLab 2 mostly works on 10.6.x, although long MP3 files may be truncated.

10.5, Leopard

MP3 playback in QLab 2 mostly works on 10.5.2+, although long MP3 files may be truncated.

MP3 playback in QLab 1 works on 10.5.2+.

MP3 playback is NOT functional AT ALL on OS 10.5.0 / 10.5.1. Apple introduced a bug into CoreAudio in these releases that caused crashes to occur when playing back MP3 files on 10.5.0 and 10.5.1.

QLab 1 and Final Cut / Soundtrack

NOTE: The following information applies only to QLab 1.3 or earlier. QLab 1.3.1 or later is NOT affected by the issue described below.

Installing Apple's Final Cut or Soundtrack software introduces a software conflict that prevents QLab 1.3 or earlier from launching when some FireWire devices are connected. The symptom is that QLab will freeze on launch. (The icon will bounce in the dock, but the application never finishes loading.) You can work around this problem by disconnecting the FireWire device, launching QLab, and re-connecting the device when QLab has finished launching.

Specifically, the following Apple audio plugin causes this issue:


If you do not require this plugin, removing it will also fix this issue.

Mac System Settings

The following system tweaks will help the reliability of playback under QLab (and any other audio software):

Energy Saver

  1. System Preferences → Energy Saver
  2. Drop down menu "Settings For" → Power Adaptor

Start Up Programs

Ensure no unneeded programs are staring up automatically. For example, Skype, Limewire, iChat & Miro will need this feature disabled in their Preferences menus.


Ensure the Airport Network is off and no network cables are attached when in show mode. (Unless, of course, you're using the network for the show, e.g. MIDI over ethernet.)

Software Update

Do not allow your Mac to perform system upgrades that may either interfere with the running show, require a restart or be untested with QLab.

  1. System Preferences → Software Update

Anti-Virus Software

Although of limited availability for the Mac anyway, no Anti-Virus software or updater should be running during a show situation.