[iiwusynth-devel] Swami: No sound in iiwusynth

[M. Nentwig]

Hei,

I found the problem, why Swami doesn't produce any sound with Iiwusynth.
It is indeed related to the default modulators: Swami creates two
modulators for MIDI controller 7 and 11, which have the wrong polarity.
So each of them adds 96 dB of attenuation. Setting their amount to 0 in
Swami fixed the problem temporarily.
There is no need to create default modulators, Iiwusynth will add them
by itself.
Probably it's more interesting to turn them off: Create an identical
modulator with negative amount. The definitions are in iiwu_synth.c, for
example

 /* SF2.01 page 55 section 8.4.5: MIDI continuous controller 7 to
initial attenuation*/
  iiwu_mod_set_source1(&default_att_mod, 7,                     /*
index=7 */
                       IIWU_MOD_CC                              /* CC=1
*/
                       | IIWU_MOD_CONCAVE                       /*
type=1 */
                       | IIWU_MOD_UNIPOLAR                      /* P=0
*/
                       | IIWU_MOD_NEGATIVE                      /* D=1
*/
                       );
  iiwu_mod_set_source2(&default_att_mod, 0, 0);                 /* No
second source */
  iiwu_mod_set_dest(&default_att_mod, GEN_ATTENUATION);         /*
Target: Initial attenuation */
  iiwu_mod_set_amount(&default_att_mod, 960.0);                 /*
Amount: 960 */

To debug modulators, edit iiwusynth and uncomment the dump_modulators
line in iiwu_voice.c:

 for (i = 0; i < voice->mod_count; i++) {
    iiwu_mod_t* mod = &voice->mod[i];
    iiwu_real_t modval = iiwu_mod_get_value(mod, voice->channel, voice);

    int dest_gen_index = mod->dest;
    iiwu_gen_t* dest_gen = &voice->gen[dest_gen_index];
    dest_gen->mod += modval;
    /*      iiwu_dump_modulator(mod); */
  };

Or put some printfs there, that's what I did.
Warning: dump_modulator is a bit buggy (some source names are muddled up
with CCs); will be fixed soon.

Cheers

Markus