To Pd developers...
I've adapted Pd to nternally use a "pdinstance" structure to allow
multiple schedulers (including DSP chains) to run in one address space.
With slight modification (see below) libpd can use this to run separate
patches asynchronously.
I tried to "instance-ize" all Pd symbols to keep them private but ran into
seemingly insoluble problems, so am leaving all symbols global for now.
(So patches used in pdlib, if they want to be usable in a multiple-instance
scenaro, should protect all send/receive/table/delay/etc named objects with
a $[0-9] somewhere.
I didn't look hard, but I thnk pdlib now will need a way to send $ arguments
to patches via libpd_openfile() somehow. Also, libpd_init_audio() will want to
make number of channels per-instance, etc. I've put some relevant comments
in the test program I'll include below (and sorry for the length of this
mail!)
Here's how I modified libpd_wrapper/z_libpd.c:
55d54
< sys_time = 0;
110c109
< sched_tick(sys_time + sys_time_per_dsp_tick);
---
> sched_tick();
130c129
< sched_tick(sys_time + sys_time_per_dsp_tick); \
---
> sched_tick(); \
----------------------
and here (sorry again) is the test program, "pdtest2.c" adapted from
libpd-master/samples/c_samples/c/pdtest.c :
---------------------
#include <stdio.h>
#include "z_libpd.h"
#include "m_imp.h"
#define TIMEUNITPERMSEC (32. * 441.)
void pdprint(const char *s) {
printf("%s", s);
}
void pdnoteon(int ch, int pitch, int vel) {
printf("noteon: %d %d %d\n", ch, pitch, vel);
}
int main(int argc, char **argv) {
t_pdinstance *pd1 = pdinstance_new(), *pd2 = pdinstance_new();
if (argc < 3) {
fprintf(stderr, "usage: %s file folder\n", argv[0]);
return -1;
}
int srate = 44100;
// maybe these two calls should be available per-instnace somehow:
libpd_set_printhook(pdprint);
libpd_set_noteonhook(pdnoteon);
/* set a "current" instance before libpd_init() or else Pd will make
an unnecessary third "default" instance. */
pd_setinstance(pd1);
libpd_init();
/* ... here we'd sure like to be able to have number of channels be
per-nstance. The sample rate is still global within Pd but we might
also consider relaxing that restrction. */
libpd_init_audio(1, 2, srate);
float inbuf[64], outbuf[128]; // one input channel, two output channels
// block size 64, one tick per buffer
pd_setinstance(pd1); // talk to first pd instance
// compute audio [; pd dsp 1(
libpd_start_message(1); // one entry in list
libpd_add_float(1.0f);
libpd_finish_message("pd", "dsp");
// open patch [; pd open file folder(
libpd_openfile(argv[1], argv[2]);
pd_setinstance(pd2);
// compute audio [; pd dsp 1(
libpd_start_message(1); // one entry in list
libpd_add_float(1.0f);
libpd_finish_message("pd", "dsp");
// open patch [; pd open file folder(
libpd_openfile(argv[1], argv[2]);
/* the follownig two messages can be sent without setting the pd nstance
and anyhow the symbols are global so they may affect multiple instances.
However, if the messages change anyhing in the pd instacne structure
(DSP state; current time; list of all canvases n our instance) those
changes will apply to the current Pd nstance, so the earlier messages,
for instance, were sensitive to which was the current one.
Note also that I'm using the fact taht $0 is set to 1003, 1004, ...
as patches are opened -it would be better to opent the patches with
settable $1, etc parameters to libpd_openfile(). */
// [; pd frequency 1 (
libpd_start_message(1); // one entry in list
libpd_add_float(1.0f);
libpd_finish_message("1003-frequency", "float");
// [; pd frequency 1 (
libpd_start_message(1); // one entry in list
libpd_add_float(2.0f);
libpd_finish_message("1004-frequency", "float");
// now run pd for ten seconds (logical time)
int i, j;
for (i = 0; i < 3; i++) {
// fill inbuf here
pd_setinstance(pd1);
libpd_process_float(1, inbuf, outbuf);
if (i < 2)
{
for (j = 0; j < 8; j++)
printf("%f ", outbuf[j]);
printf("\n");
}
pd_setinstance(pd2);
libpd_process_float(1, inbuf, outbuf);
if (i < 2)
{
for (j = 0; j < 8; j++)
printf("%f ", outbuf[j]);
printf("\n");
}
}
return 0;
}
----------------------
I replaced "test.c" as follows:
---------------------
#N canvas 406 290 450 300 10;
#X obj 97 64 loadbang;
#X obj 97 131 print;
#X obj 186 106 dac~;
#X obj 97 107 f 0;
#X obj 128 107 + 1;
#X obj 97 86 metro 2;
#X obj 185 41 r \$0-frequency;
#X obj 188 73 osc~;
#X obj 248 127 print \$0-frequency;
#X obj 248 97 loadbang;
#X connect 0 0 5 0;
#X connect 3 0 1 0;
#X connect 3 0 4 0;
#X connect 4 0 3 1;
#X connect 5 0 3 0;
#X connect 6 0 7 0;
#X connect 6 0 8 0;
#X connect 7 0 2 0;
#X connect 7 0 2 1;
#X connect 9 0 8 0;
----------------------------
and got this output:
print: 0
1003-frequency: bang
print: 0
1004-frequency: bang
1003-frequency: 1
1004-frequency: 2
1.000000 1.000000 0.999999 0.999999 0.999998 0.999998 0.999997 0.999997
1.000000 1.000000 0.999998 0.999998 0.999996 0.999996 0.999995 0.999995
print: 1
0.999944 0.999944 0.999943 0.999943 0.999942 0.999942 0.999941 0.999941
print: 1
0.999815 0.999815 0.999810 0.999810 0.999804 0.999804 0.999799 0.999799
print: 2
print: 2
... Looks like there are 2 schedulers adn DSP chains running :)
Miller
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