[PD] 64 channel audio output with RME HDSP-Madi

[Winfried Ritsch]

Hello,

the problem is in fact a wrong behaviour of PD on multichannel cards. 
Most Hammerfall has a fixed number of channels, but on dsp-madi you can choose 
and in fact it does not use enable all of the channels on hardware which 
means reduction in the PCI-load. so channels can be chossen from 1 to 64.
(In fact all  hdsp can do this but it is not implemented on the alsa-driver).

So the best way would be to respect the channel count from the user and if you 
use more than 64 it looks for the next multichannel card, so if you use 4 
madis (maximum) you have 256 channels.

I will make a patch with a cleaner solution soon, and also made an PD-external 
to use the 128x64 Mixer. from PD (since alsactl cant store all values of the 
matrix, so on startup you may have differennt settings).

Please tell me if you experience other problems, sind HDSP-Madi is not tested 
very much on different linux machines.

mfg winfried ritsch.

> > zmoelnig at iem.at wrote:
> >> now what to do against it?
> >> i have once patched the s_audio_alsa.c, so that if the requested
> >> channel is 0, this value is not clamped between the min. and max.
> >> #channels but rather set to the max. #channels.
> >> i will see if i can find it.
> >
> > Would be glad to get it!
>
> i just made this little patch which _should_ do the trick.
>
> i haven't really tested it at all (i have no MADI here at home and i am
> too lazy to compile... :-)), but i am pretty sure it will work.
>