Re: [fluid-dev] static in output

[jpyle]

When I use this (freeware) soundfont:
http://www.musik.aau.dk/~bovbjerg/Steinway%20Grand%20Piano%201.2.sfArk
then with good headphones I can hear "static" in just about every note.
 People rave about this soundfont on hammersound.net, so I don't think
it is defective when used with commercial synthesizers.
The readme that came with the soundfont said it was created with Vienna
and saved in SF2, not SF2.1 format.
I noticed that with this soundfont, just a little keyboard activity
sends my CPU level up to 52% (and it doesn't get much higher with more
keyboard activity).
Using reverb in fluidsynth makes the static echo.

I tried bypassing jack and going straight to ALSA, I tried reducing
polyphony to 8, and I tried increasing latency with the -z parameter,
but none of it helped.  I can hear static even after playing 1 or 2
notes.  Increasing latency on jackd also has no effect.

I have an M-Audio Audiophile 2496, and I'm using the ice1712 ALSA
driver.  I don't think the static could be related to the sound card
because I can record the static directly into Ardour and play it back. 
I tried looking at the waveform but the noise was less than the signal
so I couldn't see anything.  (Nor did I see any sudden dropoffs.)  Jackd
usually tells me when I get a dropout, but it has no complaints when I
use this soundfont on fluidsynth.

Quoting Garett Shulman <address@hidden>:

> Hm... I do get audio artifacts like that sometimes when I am playing
> 
> lots of voices. However, I can playback much more than 8 voices
> without 
> problem. I have not, however, tried outputing to jack. Do you get 
> different behavior when you go straight to alsa? You might also try 
> limiting the polyphony. Then, maybe, voices will just drop instead of
> 
> crackle. What kind of sound card are you using?
> 
> address@hidden wrote:
> 
> >I am using a 2.08 Ghz Athlon XP with a 333Mhz FSB, 1G "dual
> channel"
> >memory, nForce2, 2.4.21 with preemptible and low-latency patches.  I
> run
> >fluidsynth as root, through jack and sometimes ardour.  I would
> describe
> >the static as occuring whenever fluidsynth is trying to process too
> many
> >voices: either when I am pressing eight keys, using the sustain
> pedal,
> >or playing something complicated.  It isn't limited to the low
> octaves,
> >but it is much more audible there, perhaps because decays are
> longer
> >there on the grand piano soundfonts.  I've tried turning down the
> gain,
> >but that doesn't make a difference.  Using the -z parameter also
> didn't
> >help much.  Someone at:
> >http://www.altlinux.ru/pipermail/music/2003-January/000617.html 
> >described it as "crackly static distortion."  It doesn't sound like
> >clipping, but something more random, like dropouts occuring at
> random
> >intervals.
> >
> >Quoting Josh Green <address@hidden>:
> >
> >  
> >
> >>Also make sure you are running FluidSynth as root for low latency
> >>SCHED_FIFO scheduling, or alternatively increase audio card buffer
> >>size
> >>and count (thus increasing latency). Like Garett mentioned, some
> >>more
> >>info about when static is heard (particular to certain
> instruments,
> >>related to system load, constantly heard, etc) would be helpful.
> >>Regards,
> >>    Josh Green
> >>
> >>
> >>On Mon, 2004-02-16 at 19:07, Garett Shulman wrote:
> >>    
> >>
> >>>Can you give more info about you setup? Processor, Memory, OS,
> >>>      
> >>>
> >>sound 
> >>    
> >>
> >>>card? Can you be more specific about the unwanted sound you are
> >>>      
> >>>
> >>hearing? 
> >>    
> >>
> >>>It only occurs in the lower octaves with sustain? Could it be
> >>>      
> >>>
> >>clipping 
> >>    
> >>
> >>>from having the gain to high? Have you tried adjusting the gain
> in
> >>>      
> >>>
> >>>fluidsynth to something low like 0.6 or 0.3? I doubt changing the
> >>>      
> >>>
> >>code 
> >>    
> >>
> >>>will be of much help. I run a 600MB rhodes sound font (used to be
> a
> >>>      
> >>>
> >>>.gig) fine on an athlon 1700 with 750MB of ram, a delta66, and
> >>>      
> >>>
> >>alsa. 
> >>    
> >>
> >>>Sounds great even with lots of voices. The latency is unnoticable
> >>>      
> >>>
> >>to me 
> >>    
> >>
> >>>even though I don't have kernel preemption enabled and some of
> the
> >>>      
> >>>
> >>>sample data is being swapped.
> >>>-Garett
> >>>
> >>>address@hidden wrote:
> >>>
> >>>      
> >>>
> >>>>I hear static from fluidsynth when I use ~40 megabyte grand
> piano
> >>>>soundfonts and I play in the lower octaves with the sustain
> pedal
> >>>>        
> >>>>
> >>down.
> >>    
> >>
> >>>>(I've noticed CPU usage is pretty high when I do that, too). 
> >>>>        
> >>>>
> >>Does
> >>    
> >>
> >>>>anyone know ways to get around this (command line switches, code
> >>>>changes)?   I'm willing to sacrifice latency or number of
> >>>>        
> >>>>
> >>simultaneous
> >>    
> >>
> >>>>voices for a clean performance.
> >>>>
> >>>>
> >>>>_______________________________________________
> >>>>fluid-dev mailing list
> >>>>address@hidden
> >>>>http://mail.nongnu.org/mailman/listinfo/fluid-dev
> >>>> 
> >>>>
> >>>>        
> >>>>
> >>>
> >>>_______________________________________________
> >>>fluid-dev mailing list
> >>>address@hidden
> >>>http://mail.nongnu.org/mailman/listinfo/fluid-dev
> >>>      
> >>>
> >
> >
> >
> >
> >
> >_______________________________________________
> >fluid-dev mailing list
> >address@hidden
> >http://mail.nongnu.org/mailman/listinfo/fluid-dev
> >  
> >
>