ArKaos VJ: Automatic Beat-Matching

One of the great things about ArKaos VJ is that it can automatically sync the visual effects to the music. You can do this in one of two ways: automatic beat matching of audio or MIDI sync. This month we’ll look at the syncing to audio.

In order to set up a patch that will automatically sync to the beat of the music, drag-and-drop the desired loops onto your patch and assign them transitions, all controlled by controller 7 and 8. Make sure all loops are in “Latch mode” by selecting the option in the visual info dialog. (This keeps the image on the screen without having to hold down a key.)

Now go to the automation set up (Edit > Preferences > Automation). If you want to sync to MIDI Time Code on the currently selected MIDI device, choose “From MIDI Time Code.”

If you want to sync to audio, select “Use Beat Detection” in the Automation dialog. (See your OS and/or sound card documentation for more information on selecting the desired sound source and routing music to it.) The visuals will respond to the signal appearing at the currently selected audio input and the waveform will appear at the bottom of the automation dialog. If the visuals seem to be out of sync with the audio, adjust the “From Audio Input Delay Compensation” slider until they seem in alignment.

In either type of synchronization, selecting “Generate Controller 7 and 8” will cause the Automation algorithms to generate the MIDI controller 7 and 8 data that many of the effects modules in VJ respond to. This controller data increases from zero to maximum over the period of each beat, thereby allowing for smoother transitions. Adjusting the beat ratio* in the automation setup dialog allows you to control how fast the blending happens. Lower beat ratio settings result in a more strobe-like quality, while higher settings provide smoother results.

You can also get VJ to switch automatically between multiple open Synth files by selecting “Auto change synths.” Similarly, “Auto change patches” can switch between Patches with open Patch windows in the currently active Synth. The “Change after (seconds)” control sets the interval at which Patches or Synths are changed when either of the Auto change options is engaged.

*Beat Ratio: Sets the frequency with which new keys will be triggered. A beat ratio of 1 means that a key will be triggered at each beat of the music. A ratio of 2 will cause a key to be triggered every 2 beats, etc. If you are playing long video loops, you should raise this slider to a high value.

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