VST3 Program Change: 0 never transmitted (FIXED)

[pll]

Hi,

When trying to implement the Program Change support on my vst3 plugin, I find the following issue:

* MSB message value between 0 and 127 are transmitted by the DAW
* Program Change value 0 is never transmitted by the DAW
* Program Change value between 1 and 127 are transmitted by the DAW

It seems to me that Program Change should be able to send 128 values [0, 127] or [1, 128]

Do you have any information ?

[EvilDragon]

Yeah, should be 0-127.

[schwa]

Here is the code on our side:

                  int paramid=VST3_GetProgChgParamForUnit(m_vst3->m_controller, unitid);
                  if (paramid >= 0)
                  {
                    int progidx=mevt->midiData[1];
                    int progcnt=0;

                    int ui, un=uinfo->getUnitCount();
                    for (ui=0; ui < un; ++ui)
                    {
                      UnitInfo tuinfo={0};
                      uinfo->getUnitInfo(ui, tuinfo);
                      if (tuinfo.id == unitid)
                      {
                        int li, ln=uinfo->getProgramListCount();
                        for (li=0; li < ln; ++li)
                        {
                          ProgramListInfo pinfo={0};
                          uinfo->getProgramListInfo(li, pinfo);
                          if (pinfo.id == tuinfo.programListId)
                          {
                            progcnt=pinfo.programCount;
                            break;
                          }
                        }
                        break;
                      }
                    }

                    double val=m_vst3->m_controller->plainParamToNormalized(paramid, progidx);
                    if (val != (double)progidx && val >= 0.0 && val <= 1.0)
                    {
                      // plainParamToNormalized seemed to do something, accept
                    }
                    else if (progcnt > 0 && progidx >= 0 && progidx < progcnt)
                    {
                      val=(double)progidx/(double)progcnt;
                    }
                    else
                    {
                      val=-1.0;
                    }
                    if (val >= 0.0)
                    {
                      int paramidx=m_vst3->GetParamIdx(paramid);
                      VST3_SetParameter(effect, paramidx, val, 0);
                    }
                  }

There is some flexible support in there for plugins not implementing plainParamToNormalized for the program change parameter, and the return from that function will get ignored for the 0th program. But it looks to me like the only way the zero would not get transmitted at all is if the plugin also returns zero via ProgramListInfo.programCount.

[pll]

Here is what I suspect to happened when I receive a Program Change with value 0

int progidx=mevt->midiData[1] => 0
plainParamToNormalized -> [0, 1] => 0
so the check (val != (double)progidx) fail.

Then, the progCnt is 0 on my side, and I go to the error case.

There is 2 issues:
- I should change progCnt on my side to ensure the progCnt is not null.
- I should not pass in 2 differents cases when value is 0 and value is !=0, I think you should change the first check

[ivansc]

As rule of thumb, some manufacturers use 0 to 127, some use 1 to 128.

This can often lead to fun situations like the one you appear to be in right now. Fortunately, Schwa has your back.

[EvilDragon]

Actually AFAIK they all use 0-127 internally, but sometimes they display the values as 1-128 (since humans start counting from 1, heh).

[mschnell]

Originally Posted by EvilDragon

humans start counting from 1.

Finally I know what is wrong. I am not human

-Michael

[pll]

Originally Posted by schwa

and the return from that function will get ignored for the 0th program.

Could you explain why you ignore the 0th program ?