Re: [fluid-dev] problems with fluidsynth 1.1.6 on a raspberry pi

[Jan Newmarch]

Hi

I recompiled 1.1.6 with polyphony set to 64. There doesn't seem to be a
command line option to reset parameters like this, but it shouldn't be
too hard to add one. Yes I know, use fluid_settings_setXXX in the code...

Anyway... no better. Still hits CPU above 99% (!) and distorts
accordingly. 

(The pidstat command I used was
        pidtat -C fluidsynth - u -r 5
for 5 second periods.)

David gives perf figures of
        
        30% - fluid_rvoice_dsp_interpolate_4th_order
        27% - fluid_rvoice_buffers_mix
        13% - fluid_iir_filter_apply
          9% - fluid_revmodel_processmix

I ran perf (from linux-tools Debian pkg) on the RPi for nightsin.kar using two 
soundfonts and got

    32.07%   fluid_rvoice_buffers_mix
    26.89%   fluid_rvoice_dsp_interpolate_4th_order
    12.99%   fluid_iir_filter_apply
    11.00%   fluid_revmodel_processmi

for the FluidR3_Gm  and

    29.49%   fluid_rvoice_buffers_mix
    23.71%   fluid_rvoice_dsp_interpolate_4th_order
    14.89%   fluid_revmodel_processmix
    12.53%   fluid_iir_filter_apply

for the GeneralUser soundfont (which sounds a bit better).
No significant difference.

Jan
--

On Sun, 2012-11-18 at 08:31 -0700, Aere Greenway wrote:
> Jan & David:
> 
> In my opinion, limiting the polyphony (I presume that is what you mean
> by "limiting the voices") does not adversely affect the sound.  
> 
> What is using up the CPU, is voices still being 'sounded' that have
> long before faded to where they are inaudible.  sysstat

> 
> If Fluidsynth works similarly to the EMU10K1/2 (Soundblaster & Audigy)
> chip, it should 'take-out' the oldest voices first, though I don't
> know if that is actually the case.  
> 
> I think the Soundblaster and Audigy soundcards have a polyphony limit
> of 64 (I have also heard that the limit is actually 48).  And since
> the pieces sounded fine on my Soundblaster card, I tried setting the
> polyphony to 64, and it also sounded perfectly good, and cut down the
> processor load significantly.  
> 
> Trying that worked fine, with no detectable degradation in sound.  
> 
> Since I use Qsynth, I change this by changing the "Polyphony"
> parameter of the "Audio" tab (visible after clicking the "Setup"
> button.  I do not know how to make the same change using command-line
> parameters.  
> 
> 
> - Aere
> 
> -----Original Message-----
> From: David Henningsson <address@hidden>
> Reply-to: FluidSynth mailing list <address@hidden>
> To: FluidSynth mailing list <address@hidden>
> Subject: Re: [fluid-dev] problems with fluidsynth 1.1.6 on a raspberry
> pi
> Date: Sun, 18 Nov 2012 12:51:58 +0100
> 
> On 11/18/2012 11:07 AM, Jan Newmarch wrote:
> > Thanks to Christian and Aere. Here are some more results on a file
> > nightsin.kar of various choices using pidstat:
> >
> > Version     flags   sound font      cpu %   memory %        comments
> > 1.1.5       none    FluidR3_GM      75%     43%     unlistenable
> > 1.1.5       -z 4096         FluidR3_GM      70%     43%     unlistenable
> > 1.1.5       -z 4096         GeneralUser     76%     20%     unlistenable
> > 1.1.6       none    FluidR3_GM      80%     40%     still distorting
> > 1.1.6       -z 4096         FluidR3_GM      75%     40%     distorts when 
> > usage > 90%
> > 1.1.6       -z 4096         GeneralUser     65%     none shown      
> > distorts when usage > 90%
> 
> Thanks for providing a good test case. I'm not familiar with pidstat - 
> could you state the command line do you use for this, for an accurate 
> comparison?
> 
> It looks like the CPU % maybe does not differ that much.
> 
> Actually, I recently got hold of a Nexus 7 running Ubuntu [1], which has 
> a Tegra 3 core. When running NIGHTSIN.KAR (found at [2]), it does indeed 
> use a lot of CPU. It runs fine for the most part, but occasionally 
> breaks up. (This is with -z 4096.)
> 
> Running a quick perf analysis of it, the top CPU using functions are:
> 
> 30% - fluid_rvoice_dsp_interpolate_4th_order
> 27% - fluid_rvoice_buffers_mix
> 13% - fluid_iir_filter_apply
>   9% - fluid_revmodel_processmix
> 
> The interpolation can be reduced, but only inside the shell it seems 
> like, so that would help some (at the expense of quality, as usual).
> 
> Reducing the number of voices would be the first thing to try IMO, that 
> is usually not that hearable hopefully.
> 
> But this is indeed an interesting optimisation problem. At least 
> fluid_rvoice_buffers_mix should be able to run faster I believe. I'll do 
> some experiments with it when I have some more time.
> 
> // David
> 
> [1] https://wiki.ubuntu.com/Nexus7
> 
> [2] http://www.swissdom.cc/midis/karaoke-internacional-1/n/
> 
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-- 
Dr Jan Newmarch
Head of ICT and Commerce (Higher Education)

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