[PD-dev] help with some new multichannel tools

[Alexandre Torres Porres]

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.

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 at 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/remap~.c#L34
>
> cheers
>
> Em sáb., 22 de jul. de 2023 às 21:02, Alexandre Torres Porres <
> porres at gmail.com> escreveu:
>
>>
>>
>> Em sáb., 22 de jul. de 2023 às 18:39, Christof Ressi <
>> info at 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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