Re: [fluid-dev] No reverb, no chorus with 2.1.0

[midi-pascal]

On 2020-02-16 3:08 a.m., Tom M. via fluid-dev wrote:
> > I use an audio driver based on the fluidsynth_fx sample program
> How exactly does your callback function look like? The fluidsynth_fx
> example is slightly outdated. Since 2.0.0 it won't work for effects.
> I'll update it. But unless you've adjusted the callback, it does not
> really explain why 2.0.2 works for you.
>
> Also, pls. which audio driver does fluidsynth use?
>
>
>
> Tom
>
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Hi Tom,

Here is my callback function (based on fluidsynth_fx.c sample program):

int ProcessBuffer(void *data, int len, int nfx, float **fx, int nout, 
float **out)
{
  fx_data_t* fx_data = (fx_data_t*) data;
  float *out_i;
  // Call the synthesizer to fill the output buffers with its audio output.
  fluid_synth_process(fx_data->synth, len, nfx, fx, nout, out);
  fx_data->fMeterValue[0] = 0.0f;
  fx_data->fMeterValue[1] = 0.0f;
  // Apply our effects here.
  for(int i = 0; i < nout; i++) {
    out_i = out[i];
    for(int j = 0; j < len; j++) {
      // Find the peak level for this buffer run.
      const float fValue = out_i[j];
      if (fx_data->fMeterValue[i & 1] < fValue)
        fx_data->fMeterValue[i & 1] = fValue;
    }
  }
  return FLUID_OK;
}

While debugging I see that nfx is always 0 and fx is NULL.

I read carefully the fluid_synth_process() documentation and the sample 
code in fluidsynth_process.c, so I did a small change in my callback by 
adding:

  nfx = nout;
  fx = out;

just before the call to fluid_synth_process() and the reverb works now 
(no chorus but my app does not use it anyway). I am not sure if my fix 
is the right way to go, but it works (half).

With 2.0.2, the reverb worked once but I could not reproduce afterwards 
probably because my code is under construction and changes a lot.

The audio driver I use is pulseaudio.

Regards,

Pascal