How do I reset a ramp signal at audio rate?

Question

This is a follow on question to my question about reading VCS controls at 4000hz.

My Ferranti Oscillator sound is starting to work! Thanks to SSC for the pointer to the InputOutputCharacteristic sound.

I am using a full wave ramp to index through the array of VCS toggle buttons and that works great.

What I wanted to do next was have a VCS control to set the number of steps to cycle through the array. So although I've got 60 toggle buttons on the screen, I might want to just cycle through the first 12.

I used an Equality sound to compare the output of the ramp Oscillator with a VCS slider. I fed the output of that into a SoundToGlobalController which then sets a !Reset event value. This event value is in the Reset parameter of the oscillator. My intention is that if I set the slider to about 20% along, the ramp wave should reset after stepping through 12 of the toggle buttons.

But instead what happens is if the slider is set to anything less than 50% it doesn't seem to have any effect and after 50% it's erratic. I'm assuming this is an issue of the SoundToGlobalController using the control sample rate on its value parameter.

So how would I reset the ramp after it's read through 12 (or an arbitrary number of) steps?

 

 

The sound file

 

 

Answer 1

Have you tried using a TimeIndex Sound in place of the Oscillator on fullRamp?  The TimeIndex has a choice of loop modes and loop points.  For example, to cycle through the first 12 out of 16, you could set the loop-end parameter to: 12/60.  Or make it adjustable using !Steps / 60.  Once you get that working, you could consider whether or not to add an adjustable start-point as well.

Comments

That worked great, thanks. I'll post the updated sound in another answer...

Answer 2

Based on SSC's suggestion of using the TimeIndex sound here is the simplified sound.

 

Ferranti Sound - Version 2

Answer 3

You should have a look at ProfessorBraff's TimeIndexModulo and TimeindexPhaseShift, two modules we designed together with the NeverEngine Labs. Combined with ScaleAndOffset I guess they could do any of the timeindex tricks you are looking for.