I am working on a patch to use audio information as a triggering mechanism for live video effects. Basically, right now I'm trying to produce bangs on bass or snare hits. I am attempting to isolate the hits using a lowpass [lop~] and bandpass [bp~] and [highpass~] filters (though only a lowpass is used in the patch that I'm posting, any combination of filters can be inserted in it's place). [moses] only sends information from the right outlet when the signal received from [env~] (a measure of amplitude) is higher than the "trigger cutoff" sent to the right inlet.

I want to use this to manipulate video projections during live shows using the audio the band is putting out. Does anyone have any advice for better ways to isolate specific frequencies so I can narrow the triggering down to just the hits I want to trigger bangs?

http://www.pdpatchrepo.info/hurleur/audio_trigger_using_env.pd

if it's for live audio manipulation the best way to have precise control over the detection of hits is to send the kick and snare of whatever your source is to different channels and have pd listen in on those channels. Then it can't go wrong. If it's a live gig, take feeds from the mixing desk e.t.c.

bonk~ is designed for this (you can train it with your drum kit so it knows which sounds are which).

awesome.
thanks for the feedback. i'm projecting during live gigs so i'll definitely run an out from the main mixing board. also, i'll look into bonk~. i've been working on a new version of the patch i uploaded that filters out most of the extraneous bangs that get sent in the above version. once i figure out the detection issue in regards to narrowing down the sample, maybe using bonk~, i'll put it up.

@ClaudiusMaximus said:

bonk~ is designed for this (you can train it with your drum kit so it knows which sounds are which).

i am working on a similar sort of project in order to manipulate video for an a/v interactive installation, i am using bonk~ to analyze the stream of data coming in. I will be using a firepod with 6 lines into pd. essentially i would like to know about training bonk~ any advice or links would be much appreciated!

http://www-crca.ucsd.edu/~msp/Publications/icmc98.ps talks a bit about theory, not sure if there is a more practical explanation somewhere - althought the help patch on the right says this about the "learn $1" message: "Forget all templates and start learning new ones. The argument gives the number of times you will hit each instrument (10 recommended.) Turn on the output volume above for audible feedback as you train Bonk. "Learn 0" exits learn mode."

Here's the latest version of my trigger-on-beat patch.

In the original version each time the patch should trigger it sends hundreds of bangs, this version solves that problem by firing only one bang for every time a beat exceeds the cutoff point.

To test, just set the cutoff points on the [lop~] and [moses] objects and clap into the microphone.

For live shows I take a feed from the drum mixer and run it into my laptop, through this patch (used as a subpatch in a larger fx patch), and use it to trigger effects changes on the beat.

Any feedback is welcome.

http://www.pdpatchrepo.info/hurleur/audio_trigger_using_env.pd