Video Trigger

Free Motion Detector App for Media Artists

Attach a camera and trigger sounds whenever occupancy is detected in six user-defined areas of the video image. You have complete control over the playback logic and signal routing. Multichannel surround is supported. Video Trigger can also trigger shell scripts or AppleScripts! If you want to trigger videos to play instead of sounds, see my other app, Video Triggers Video.

I designed Video Trigger for artists who want to experiment with interactivity without building custom hardware or software. It aims to answer the question that I hear from many of my students:

“How do I make a sound play when somebody walks by?”

The answer often involves micro-controllers (like Arduino) and sensors, or custom software (via Processing, pd, vvvv, Isadora, or MAX). In the long-run these options provide much greater rewards, but if you have modest needs, Video Trigger is a painless way to get started.

Video Trigger works with many cameras. It can play up to six sound files (AIFF or WAV, 1-16 channels) through any Core Audio sound hardware (1-16 channels) with complete control over signal routing.

Whenever a zone is entered or exited it can also run a terminal command of your choice (to launch an Apple Script or shell script, run an application, open a file, etc. )

Video Trigger is not security software. It won’t email you a video of somebody breaking into your house! Try iSentry, iSpy, BTV Pro, SecuritySpy, or Blue Iris.

VPT (Video Projection Tool) is a free app by HC Gilje that handles all kinds of complicated video projection tasks (cueing, mixing, effects, keystoning, etc…). He made a VPT extension based on Video Trigger so you can use a camera to trigger any VPT function.

Sometimes video motion detection is a complex and unreliable way to detect people. A simple floor switch or motion detector attached to a Sparkfun WAV Trigger, hacked computer keyboard or Makey Makey board could do the job nicely. Applications like the (free and wonderful) Soundplant will play sounds whenever a key is pressed, with fine control over the playback logic.

Download Latest Version (2018-08-20) 90MB MacOS .dmg file

Read the Video Trigger Guide for instructions and a detailed Changelog.
See Installation Instructions. There is no Windows version (details).

Changes in this version:

  • Recompiled using Max 7 to make it more compatible with recent MacOS versions.
  • No longer needs JAVA (hooray!)
  • Now plays compressed formats (mp3, AAC)
  • Added elapsed time counter for each zone’s audio player
  • Minimum fade in/out time is now 5 msec (was 10)
  • Enter/exit behavior can now be swapped (so playback can stop when zone is occupied, and continue when zone is exited)
  • If using a movie as an input source, the audio can be optionally muted
  • Fixed: output routing matrix is no longer cleared every time you load a soundfile (only clears when you load a file with a different number of channels than the last one)
  • Fixed: script triggering was broken in recent OS versions
  • Fixed: updated online docs URL for recent website redesign
  • Lots of internal code cleanup to make patch easier to modify and update
  • “simple_beep.scpt” Apple Script is included and ready to enable in the Script Settings
Like Video Trigger? Donations are appreciated. (sorry, not tax-deductible)

Old Versions

2013-03-28 (Mac Intel, Not Compatible with PPC Macs) March 28, 2013, 20MB with MAX6 source patches.

2012-08-11 (Mac Intel, Not Compatible with PPC Macs) Aug 11, 2012, 20MB with MAX6 source patches.
2009-01-10 (Mac Intel/PPC) Jan 10, 2009, 17MB with source “patches” for MAX5. (Tested with Mac OS 10.5 Leopard.)