[fluid-dev] Re: What is the best way start fluidsynth with zero/low latency? (Louis B.)

[jimmy]

> Date: Sat, 23 May 2009 13:50:49 +0100
> From: "Louis B." <address@hidden>
> 
> The point I was trying to make was that fluidsynth can be
> rather
> difficult for non techie users to get running correctly
> especially
> with low latency.

I still suggest they use qsynth to start fluidsynth.  Do mention that if they 
have a problem with qsynth,  they can try to start fluidsynth manually.  Once 
they use qsynth to start fluidsynth, they can use:

   ps -ef | grep fluidsynth

to get the commandline that qsynth uses to start fluidsynth.  With that info, 
they can start fluidsynth themselves from the commandline, or from a script.  
They can learn more about fluidsynth commandline options after that if they 
want.




> The more I think about it a fluid-start and fluid-stop
> script might
> make it very easy for non techie users to startup
> fluidsynth with low
> latency. It could do a "cat /proc/cpuinfo | grep MHz" to
> determine if
> users had a low, medium or high powered machine. Now that
> FluidR3_GM.sf2 is pretty good this script could
> automatically start
> fluid with that sound font (Is FluidR3_GM.sf2 available to
> most Linux
> distribution? are there any licensing restrictions with
> FluidR3_GM.sf2?). It is just an idea anyway.

I may have read somewhere, or have the impression that Intel Atom is just a new 
release of the i386 core (or i486), probably with socket (pins) change.  
Remember the netbooks are for web browsing, not a speed daemon.  Basically they 
have the same CPU speed as 7-10 year old laptop.

I have qsynth, qjackctl running OK on a 700MHz, 256MB RAM notebook.  The 
problem may also be lack of memory when using a large soundfont file, which 
does require memory swapping, affecting response time.  On that machine, I have 
to use a small soundfont.  Do note proper IRQ, and process priority settings 
may improve response time, as mention in one of the links of my last message on 
this thread.



> There is always the problem with underruns,  My atom
> baised NetBook is
> probably a good example of the absolutely the lowest spec
> machine that
> could run with low latency. Hopefully the main stream
> Linux
> distributions will improve to guarantee a quality of
> service to
> fluidsynth.

You may get underruns if you try to use too low a response time settings.  Bump 
it up 2-4 times the minimum should get rid of most underruns with just a slight 
compromise on real-time playing, which may be no worse than playing "strings", 
or "synthesized voice" instruments.

Jimmy