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

[David Henningsson]

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/