Re: [fluid-dev] Delay and buffer size

[Z F]

Dear Josh Green

Thank you very much for your thorough explanations.
I did put "-o audio.alsa.device=hw:0" option to make fluidsynth
consume 10% instead of 100% of CPU.

Thanks again

ZF

--- Josh Green <address@hidden> wrote:

> On Thu, 2006-10-12 at 19:41 -0700, Z F wrote:
> > Hello everybody,
> > 
> > I have read in the list archives that if there is noise while
> switching
> > windows, than the buffers and the number of them needs to be
> increased.
> > this will, however, will increase the delay in responce.
> > On my system I had to do fluidsynth -c 16 -z 1024 to get rid of the
> > noise. The question is than is, what is the delay in ms(?) compared
> to
> > the default. And also, what kind of delay will not be noticable?
> > 
> > Thanks for your help
> > 
> > ZF
> > 
> 
> Hello.
> 
> It depends on what sampling rate you are running at.  But if you are
> running at 44100 then you should calculate the delay like so:
> 
> (16 * 1024) / 44100 = ~372 Milliseconds
> 
> For live work, that would likely be very noticeable latency.  You can
> likely get better latency (with little or no artifacts) by running
> FluidSynth as root.  There is currently the danger of machine lockup
> though, if all CPU is consumed.  This can be limited by setting the
> maximum number of allowable voices.  There may be latency issues with
> the kernel you are running too.  That's an art in itself though, in
> getting a good low latency kernel.  Some kernel versions in 2.6 are
> rather bad, others are better.
> 
> One other thing to try is make sure you are using the ALSA hardware
> device rather than the plugin system.  This can be done by passing
> the
> following switches to FluidSynth "-o audio.alsa.device=hw:0".
> 
> Max number of voices can be set with: "-o synth.polyphony 64".  That
> will set the max number of voices to 64.  You may want to try
> something
> lower perhaps first when running as root to make sure all your CPU
> isn't
> consumed when all voices are used (a very good possibility when
> playing
> MIDI files).
> 
> There is likely a lot that could be done coding wise with FluidSynth
> to
> improve things, in this regard.  Not sure when I will get around to
> it
> though.
>       Josh Green
> 
> 
> 


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