Re: [fluid-dev] DSP testing

[Peter Hanappe]

Josh Green wrote:
> On Tue, 2004-03-30 at 02:21, Peter Hanappe wrote:
>
> > > I have a feeling there are probably some issues with stereo output in
> > > regards to the phase offset between right/left speakers. Is there
> > > currently a way to guarantee multiple voices to all start at the same
> > > time? Playing the same note can often sound different for each note on.
> >
> > No, there currently is any way to guarantee they start together. It
> > could happen that the audio thread intervenes between the initialization
> > of the first voice and the initialization of the second voice, in which
> > case the two voices are shifted by 64 samples. I should test whether
> > this really happens and think of a way to fix it if it does. Good point.
> >
> > What suprises me is that it makes that big a difference that you hear
> > it. Is there any way you could record it?
>
>
> As Tim Goetze mentioned, a 64 sample offset is enough to expose
> different phasing effects between samples. I'll see about recording an
> example.

You're right about the phasing effects. What I had in mind when I wrote
that was a 64 sample delay between the sample going to the left channel
and the sample going to the right channel.


> > > I've noticed that the damping parameter has no effect (at least as far
> > > as I can hear). Perhaps its just really subtle in its effect?
> >
> > Did you try the version in CVS? I find that the reverb has improved
> > and the effects seem more intuitive now.
>
>
> I just downloaded it and gave it a try. Wow! Much better sounding reverb
> :)  Instruments sound much more vibrant now. I still can't notice any
> change though when modifying the damping parameter. Perhaps I should try
> the original Freeverb to see if it has the same effect (or non-effect
> rather).

I quickly did a test and I've put two files on the web site:

  http://www.fluidsynth.org/test-reverb-damp-0.wav, and
  http://www.fluidsynth.org/test-reverb-damp-1.wav

In the first recording the damping equals 0, in the second 1. Roomsize
and width are 0.5 in both.


P

> > Cheers,
> > Peter
>
>
> Cheers.
>         Josh Green