Hello all,

I'm having a hard time to achieve the following:

I have an audio signal that is 1 for 14 samples then 0, when it's "1" I'd like to output a "1" signal, then the next sample I'd like to output zero, in order to know at which sample the change occurred.

I want to avoid using "block~" to set audio block to 1 in a subpatch, and don't want to use externals.

Anyone has a clue about how to achieve this ?

Cheers

@y0g1 When you say "1" signal do you mean float 1?
Even with [block~ 1] you will not get the control rate data until the end of the 64 sample Pd block.
You can visualize it with an array after the fact......... a lot of discussion of samplewise stuff here......... https://forum.puredata.info/topic/13317/looking-for-velvet-noise-generator/69
and also using [print~]
Both Vanilla.

No time at the moment but you could play with [env~ 2 1] which should give you the data... again after the fact.......
David.

@whale-av said:

https://forum.puredata.info/topic/13317/looking-for-velvet-noise-generator/69

Hello, thank you,

"env~" outputs a float, I think my question is confusing.

I'll try to be more precise, I'm analysing audio input signals, 4 audio inputs.
They are mics placed around a snare drumhead, each time there's an attack I generate
a signal that is 1 for all mics.

This signal is long, a few samples long, and I was scratching my head to find a way to turn it only into a 1 sample long impulse. It would make my life much easier.

all this stays at signal rate, then once a hit on the snare was detected on all 4 mics, I'll get the difference in samples in between them in order to know the position on the drumhead where the hit occurred.

thanks for the link to discussion, I'll read more into it to see if I can extract infos that could help. Any link to other posts about samplewise ways of doing things in general is welcome!

@y0g1 David asked all the questions I would've asked and now I get the benefit of added clarity . I wonder if this thing I made for @eeight has any useful ideas for you, especially the stuff up to the [rzero~] and [clip~] inclusive? https://forum.pdpatchrepo.info/topic/13739/sync-in-ms-between-2-audio-signals/6

Maybe if you just take the impulses on the leading edges and compare their timings (uh, somehow), that will give you the info you need. I'm hand waving because I don't know how you'd determine which impulse was first.

Edit: I think the premise of your project is that the sound of the bead of the stick hitting the batter head is dominant. I wonder if that's true for a snare drum.

@y0g1 said:

This signal is long, a few samples long, and I was scratching my head to find a way to turn it only into a 1 sample long impulse. It would make my life much easier.

i'm really not sure if i understand - but if it was only about that, a simple clipped derivative should be enough?

[rzero~ 1]
|
[max~]

but based on the rest of the discussion, it sounds like you want to know which mic received the first input? i assume that it's not enough to have this per block though - since some mics might have a rising edge in the block after the mic that detected first? (EDIT: when handling things on control rate)

EDIT: it should be doable though to only trigger one impulse each time after a defined "cooldown" period (not sure about the proper word here) on signal rate.

EDIT2: and if it's about counting samples from the first hit to the others and then triangulating - that should also be achievable. let me know whether i understand correctly first.

@jameslo said:

https://forum.pdpatchrepo.info/topic/13739/sync-in-ms-between-2-audio-signals/6

Hello,

your "metronome timer" patch contains the answer to my question, great !
( quite impressed by the reactivity on this forum )

I would have never thought of "rpole", "rzero", never used those it's a bit hard to understand how it works. The patch is well commented but still if you could detail a tiny bit the part where you take the impulse that would be lovely.

For knowing which one arrived first, I made a sample counter, but still I have to find out how to reset it when first mic is getting the signal. ( So being able to have only impulses might help me go further )

At least I know where to ask if I'm stuck again

@y0g1 The formula for [rzero~] in help means "the output is the difference between the current input and (the previous input times the current coefficient)." Since the coefficient is always 1, it's just the difference between the last two inputs. So since the input is just a square wave toggling between 0 and 1, the output is going to be 1 on the rising edge, -1 on the falling edge, and 0 otherwise. By clipping it to 0..1, I just take the rising edge pulse.

"Convert to negative pulse" means instead of sitting at 0 with the occasional 1 pulse, it now sits at 1 with the occasional 0 pulse.

The formula for [rpole~ 1] in help means ""the output is the sum of the current input plus (the previous output times the current coefficient)." When both the input and coefficient are 0, the output is 0, and when they're both 1, it increments by 1 each sample (i.e. counts samples).

By now you probably know how to understand the formula for [rzero_rev~ 0], let me know if you don't. The reason you need it is so that [samphold~] grabs the highest previous count, not the reset value.

@jameslo Thank you for the detailed explanations! I feel smarter than yesterday.

Though I noticed my signal is in fact a succession of 1 and 0, over a period of a dozen of samples, any advice about how to "debounce", I'd like my signal to be one , then 0 for 4410 samples ( ignoring all the next "1" ).

I hope it's clear, I can precise things, but I'd need to get my head out of it for an hour to do so... I'm way out of my comfort zone dealing with sample accuracy...