Re: [fluid-dev] Cutoff Frequency Effect

[Josh Green]

On Wed, 2009-03-25 at 07:49 +0200, Graham Goode wrote:
> Hi,
> Is there a cutoff frequency effect in Fluidsynth like the TVF Cutoff
> Frequency effect in Creative Cards where you set up the NRPN
> controller with:
>   176,99,1
>   176,98,32
> and then send CC 6 to apply the cutoff filter, like so:
>   176,6,xxx
> where the xxx value ranges from 0-127?
> Regards,
> GrahamG
> 

Hello Graham,

FluidSynth should respond to SoundFont NRPN messages as described in
section "9.6.2 The NRPN Select Values" of the SoundFont 2.4 PDF
specification:
http://freepats.opensrc.org/sf2/sfspec24.pdf

One example shows that by sending NRPN MSB of 120 followed by LSB of 8,
will control the Low Pass filter cutoff.  The data value is passed as a
14 bit offset value, 0x2000 (8192) being the mid point (offset value of
0), 0 being -8192 and 0x3FFF (16383) being +8191.  This value offsets
the current effect value by the native SoundFont units for the selected
parameter.

You could also edit the SoundFont and add a modulator attached to a MIDI
Custom Controller.

Best regards,
        Josh