[PD-dev] help designing multichannel aware externals

[Christof Ressi]

The implementation of signal_setoutchans() looks good to me! There is 
indeed no danger of breaking signal aliasing. Since the dummy output 
signals are "empty" (s_nchans = 0), they are allocated from the "borrow" 
free list and not from the "real" free list. Nice :-)

I think signal_setoutchans() is quite elegant and pleasant to use. Thanks!

Christof

On 25.01.2023 18:04, info at christofressi.com wrote:
> > yep - and in fact I need length to be correct, otherwise there's no 
> easy way
> to get it.
>
> That's what I was hinting at :-)
>
> I find the empty signal quite elegant. Only s_nchans and s_vec are 0, 
> the rest stays intact. This makes sense conceptionally because 
> s_nchans * s_length is still 0.
>
> > sp[2] = signal_makemultichannels(sp[2], outchans);
>
> I like this! I think the naming is very descriptive.
>
> Christof
>
> Am 25.01.2023 17:39 schrieb Miller Puckette via Pd-dev 
> <pd-dev at lists.iem.at>:
>
>     On Wed, Jan 25, 2023 at 05:34:48PM +0100, IOhannes m zmoelnig wrote:
>
>     > conceptually, i like this; though i would suggest "channels=0;
>     length=64"
>     > (or whatever).
>     >
>     yep - and in fact I need length to be correct, otherwise there's
>     no easy way
>     to get it.
>
>     > > and instead of (for example)
>     > >     sp[2] = signal_swapforchans(sp[2], outchans);
>     > > you'd just write
>     > >     signal_setchans(sp[2], ouchans).
>     >
>     > hmm, wouldn't that modify the t_signal* struct that sp[2] points
>     to,
>     > potentially breaking the reuse? (so it ought to be
>     "signal_setchans(&sp[2],
>     > outchans)")
>     >
>     I _think_ it works just to pass sp[2] in place - it's a (t_signal
>     *) and
>     all that's needed is to alter member element s_vec, s_nchans.
>
>     > and i find the "swapforchans" slightly confusing (which fo(u)r
>     channels are
>     > being swapped? the actual swapping is done by re-assigning a new
>     value to
>     > sp[2]).
>     > so how about:
>     >   sp[2] = signal_makemultichannels(sp[2], outchans);
>     >
>     so this would become moot.
>     >
>
>
>
>
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