[iiwusynth-devel] NRPN System

[Peter Hanappe]

Hi all,

I implemented a first version of the NRPN system. The NRPN midi
messages allow the control of the synthesis parameters, or generators,
in real-time. To change a parameter the following suite of MIDI
messages have to be sent:

  cc chan=0 ctrl=99 val=120                         = NRPN_MSB
  cc chan=0 ctrl=98 val=<generator number>          = NRPN_LSB
  cc chan=0 ctrl=38 val=<data LSB>                  = DATA_ENTRY_LSB
  cc chan=0 ctrl=06 val=<data MSB>                  = DATA_ENTRY_MSB

For a list of generator numbers, see the 'iiwu_gen_type' in iiwusynth.h,
or section 8.1.2 in the SoundFont specifications.

I added a new API function that is a little more to the point:

 int iiwu_synth_set_gen(iiwu_synth_t* synth, int chan, int gen, float value)

Note that the given value adds up to the value
specified in the soundfont. For the useful value ranges, check section
8.1.2 in the specifications again. The synthesizer should clip the
values internally to the allowed range. I also added 'iiwu_synth_get_gen'.

Cheers,
Peter