[PD-dev] help with some new multichannel tools

[Alexandre Torres Porres]

On Sun, 23 Jul 2023 at 00:10 Alexandre Torres Porres <porres at 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 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
>>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-dev/attachments/20230723/9434c644/attachment.htm>