[SOLVED] stop a gen phasor after one period

. . . . it's for a simple one-shot envelope generator source.

SOLVED

thanks to an old thread where vichug provided this (in a different context), and thanks to his annotations I hacked it.

It allows for a one shot 0. --> 1. --> 0. phasor ramp, that waits at 0. Now I can make all sorts of nice sample accurate envelopes. Brendan

Here is another slightly different version, I think it's a little better CPU wise.

another version with gate and retrig mode.

when retrig mode is 0, it allows the ramp to reach 1 even if it receives a new trig. it's made with the codebox, but don't worry, it's not that complicated, and more practical.

I hope this can be of any help to you.

well..; happy to have been unknowingly of some help at some point anyway :)

:)

I tend to hold on to patches like these, never know when they'll come in handy, so thanks again.

Bertrand, those are very economical and transparent, many thanks.

Brendan

thanks brendan, nice to be of some help.

there's one little mistake, for timing accuracy, you need to change this (accum (1, trig)

to (accum (1, trig)

hey! no its ugly , but

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Note to self; check the forums next time before you try to solve something and end up banging your head against the wall...

Apparently the banging helped so here's my version

And to add insult to injury; Looks at patches in thread > hey, i recognize these! Searches folder with handy stuff saved from the forum; well i'll be darned!

Use accum, not phasor.

Hz -> / samplerate -> accum -> clip 0 1 will give you a one shot ramp. A trigger to the accum's 2nd inlet will reset it.

If you want the end of the ramp to land at 0 again, send the result through a wrap 0 1.

If you don't want the accum to start counting when the patch loads, use accum @init 1

Graham

Been struggling with this myself today trying to implement one-shot sample buffer playing using phasor. The accum method makes more logic sense but if I remember correctly there's mention of this in Generating Sound & Organising Time that says don't use that method for different pitches because of aliasing. Maybe I remembered wrongly.

Edit: I should say that I'm trying to implement sample playback that can do variable pitch, forwards/reverse and looping/not-looping. Aware this is probably one of the most fundamental things but so far the mental gymnastics are leaving me fatigued. I'm still not past the part where you stop thinking like Max.

Using accum for different pitches is fine, accum will happy accumulate non-integer values as you need. But one thing to watch out for, if you are playing from a buffer~ you need to make sure you are reading with some kind of interpolation, since you aren't going to be reading integer sample positions (I suspect that's what you were thinking of from the GO book).

Basically when you play a buffer at almost any desirable pitch, you need to move through it at fractional sample steps, which means you need data from points between actual neighbouring sample values in the buffer itself. This data doesn't exist so you have to approximate it from the neighbouring sample values. That's what interpolation does. The simplest form of interpolation is linear, which means guessing that the path from one sample to the next is a straight line. It's not the best interpolation, but it is very cheap and does a great job a lot of the time.

For that, you can send the accum output to a [peek mybuf @interp linear], where mybuf is whatever your buffer's name is.

Thanks Graham, appreciate the reply. I think you're right about my ill-remembered GO quote (don't have my copy in front of my right now, will dig back through when I'm home at the weekend).

I think I'm lacking the logic chops to understand how you stop a sample at an arbitrary point (given that sending a 1, or whatever, to drive your accum object is....always a 1 so there's no way, in my brain, that you can can internally stop a buffer from playing. Obviously allowing the index to go beyond 1. will just run out of data and it stops making sound. But say you have a 5 second sample in a buffer and only want to play it from 1s to 2s and stop, that seems impossible under control). I will add that I'm a seasoned Max developer but have taken my first steps in Gen. I guess I'm falling for all the Gen Beginner Traps 🤣

Finally something is sinking in! 🤣

Made a little Gen sample player that has pitch control, direction control, optional looping and the ability to set a start->end slice of the buffer. I feel like I really achieved something here. Went back to Graham's book to realign myself with Gen-think. 🙏 I'd be curious to hear from any season Gen people to see where I might have done better. 👍