Envelop extraction for laser sync

[kecked]

Lots of posts today

I have some passages that I want to do real tight timing on that are rhythmic. Is there a way to xtract a visual envelop of the audio and show it on the time line so I can set markers better than using my hand and a mouse? I want to have some objects pop on and off the screen real fast in response to a drum part but also want to do some rather fancy rotations and such to match. To make this work I have to be nearly to the 100ms to make it work. If I could see the amplitude peaks as markers it would be really easy to make it work. Oh I work in ld2000 and beyond.

[tribble]

I had a similar need. In Beyond, you can expand the audio track slightly and zoom the timeline down pretty far, to 1ms resolution I believe. My issue was that the audio envelope was not high-enough resolution in amplitude to show me the hits in the quiet parts of the track or when they were embedded in other sounds. I ended up looking at the waveform in NCH wavepad, getting the timing, and just aligning to the ms in Beyond by time.

There is a discussion of this over on the pangolin forum.

[LaserCo]

colouredmirrorball cmb created something to trigger in this fashion for LSX, an expression that uses OSC to send commands to an EtherDream DAC.

[kecked]

I am experimenting with an envelop follower. I'm going to take the output of that and see if I can make midi from it by driving an osc and then converting to midi. I'm setting my own scale that defines the peaks. The interval defines the scale of two notes. Once I have this I can put it on one channel of audio so I can see the markers. The other way I might do this is to first put it through a gate first so only the peaks pass. Once again removing the peaks to convert to markers. Using bandpass filters I might be able to isolate instruments like the bass drum or cymbals. Then pass the signal through the gate to extract the peaks. We shall see. This should be pretty easy to program as a software dsp.

[kecked]

I tried my idea and it works. What you do is take the file and first use an eq. I used a parametric. to find the beat you like and then isolate the frequency. Now you run a strict gate over it to just pick out the peaks. Next you blow up the file volume to make all the peaks saturate at 100%. You now have just the peaks. You can clean it up a bit more with a second gate treatment. Next I have to take this into a sound to midi convertor to make the beat file.

I attached an example. One is a high pass the other a low pass the third the unprocessed. Grant you this was only drums so it was easy but the principle is the same. if you slice the frequency tight enough it will work for drums at least since they don't change note often.