Re: [fluid-dev] Gain distortion with many soundfonts

[Josh Green]

Hello Bernat,

Sorry it took me so long to answer your question.  Unfortunately I'm not
sure currently what exactly causes this issue and I haven't yet really
put any time into figuring it out yet either.  As you mentioned though,
it does indeed seem like its a distortion that occurs even though the
sound card output is not maxed, which would indicate internal distortion
of some sort.  I suspect it might have to do with reverb or chorus (try
turning them off) or perhaps with the volume attenuation of samples and
how they are mixed.

I've added a ticket for this issue here:
http://fluidsynth.resonance.org/trac/ticket/13

I'm currently working on getting Swami 2.0 released after which I'll be
putting some more time into FluidSynth.

Thanks for reporting this issue and your other findings.

        Josh


On Mon, 2008-03-17 at 02:03 +0100, Bernat Arlandis i Mañó wrote:
> I've done some more investigation. Connecting Fluidsynth output to
> Rezound I've saved the waveforms with lower gain (no distortion) and
> higher gain (with distortion). I've always avoided clipping that occurs
> at very high gain levels. I've used piano soundfonts, mainly the
> "Microfont piano collection (6MB)" soundfont.
> 
> I've compared the same sound with distortion and without distortion and
> I've discovered that the distortion is caused by the gain changes alone,
> but I don't know why some samples don't get distorted. For example, the
> "triangle simple" preset in Vintage Dreams soundfont can be maxed with
> gain 140 without any distortion before it starts clipping.
> 
> I'm not an audio expert and I certainly missing something. I've tried to
> ensure soundcard and speakers are not the problem. I can supply the wave
> files tested. Please, could someone throw some light?
> 
> Thank you.
>