Re: [PD-dev] Fwd: help with some new multichannel tools

Em dom., 23 de jul. de 2023 às 19:41, Christof Ressi info@christofressi.com escreveu:

Side note: why do your channel indexes start at 1?

I do this in some objects although I may be doing things inconsistently

in this case the idea is that "0" means "none" and I do this in other similar objects, like [xselect~], makes good intuitive sense to me.

thanks for all the help

Pd uses zero-based indexes for almost anything, with only few exceptions (ADC/DAC and MIDI channels, anything else?).

Christof On 23.07.2023 05:59, Alexandre Torres Porres wrote:

On Sun, 23 Jul 2023 at 00:10 Alexandre Torres Porres porres@gmail.com wrote:

...

I see now I was just doing something silly thinking I was trying to copy some sophisticated trick that would sove things.

I can't remember now which object I had to deal with something like this.

Found one, copied the structure, it works! I still have no good idea on how things work, but hey, I got it working and I can sleep

Thanks

...

anyway, in this last version, I have my own "perform" method that fails equally as before in some cases, but it is not as weird as before...

let me just copy it instead of linking to a github code that might change, here's the code section

*static* t_int *remap_perform(t_int *w){

t_remap *x = (t_remap *)(w[1]);

t_int n = (t_int)(w[2]);

t_int nchans = (t_int)(w[3]);

t_sample *in = (t_sample *)(w[4]);

t_sample *out = (t_sample *)(w[5]);

*for*(*int* i = 0; i < x->x_n; i++){ // channels to copy

    *int* ch = x->x_vec[i].a_w.w_float - 1; // get channel number

    *if*(ch >= nchans)

        ch = nchans - 1;

    *for*(*int* j = 0; j < n; j++){ // j is sample number of each

channel

        *if*(ch >= 0)

            *out++ = in[ch*n + j];

        *else*

            *out++ = 0;

    }

}

*return*(w+6);

}

Em sáb., 22 de jul. de 2023 às 21:22, Alexandre Torres Porres < porres@gmail.com> escreveu:

...

ok, I was able to compile a version that does not blow pd up

obviously I have no idea of what I am doing and I did some things based on warnings I was getting, but then, I do copy the input first and then reorder the channels but I do get the exact same result as before, so it was all for nothing.

here's my new attempt, hopefully not too far from getting things right https://github.com/porres/pd-else/blob/master/Code_source/Compiled/signal/re...

cheers

Em sáb., 22 de jul. de 2023 às 21:02, Alexandre Torres Porres < porres@gmail.com> escreveu:

...

Em sáb., 22 de jul. de 2023 às 18:39, Christof Ressi < info@christofressi.com> escreveu:

...

if the input and output signals have the same channel count, they will alias each other, just like in regular single-channel objects.

actually, funny stuff happens for 4 multichannel input and 3 multichannel output, but I've seen that issue with single channel objects and I tried copying stuff from other objects in ELSE into this multichannel idea and failed.

...

You first need to copy the whole input signal to a temporary buffer (probably allocated in your object) and then copy the corresponding channels to the output signal.

I wonder if you can give me a better detailed strategy/steps.

thanks

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