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Re: [fluid-dev] Very high CPU usage and dropouts on Mac version

From: Edward Costello
Subject: Re: [fluid-dev] Very high CPU usage and dropouts on Mac version
Date: Fri, 27 May 2011 13:38:54 +0100


I was able to solve this problem, it seems that certain instruments in the soundfont had very long release times specified in their presets, by shortening them less cpu was used, I don't understand why the Linux version was able to handle it just fine though,

On Thursday 26 May 2011 at 20:48, Ed Costello wrote:

Hi Pedro,

Its an Intel Macbook pro running OS X 10.6.7, I was using just the default settings of qsynth and have tried increasing the buffersize which had no effect, I am not using the chorus or reverb effects either, I tried using your build of qsynth and there was no difference in performance. I am playing back quite a large soundfont file its 500 mb or so big but it has 25 instruments in it and only 5 of them are playing at one time, I didn't think this was an issue though as it plays back just fine on Ubuntu. Also when I run the 1.1.3 command line version and the sound begins to dropout there are no error messages that come up even when the sound is gone completely.


On 26 May 2011 19:41, Pedro Lopez-Cabanillas <address@hidden> wrote:
On Thursday 26 May 2011, Ed Costello wrote:
> Hi list,
> I am using the Mac version of qsynth and I am getting very high CPU usage
> when I send midi data to the synth, 50-60 % and even as high as 90%, this is
> causing very bad audio dropouts, I thought at first it had something to do
> with the soundfont I was using but I tried the same setup on Ubuntu and
> everything played fine, the CPU was around 12% most of the time. I tested
> this with Logic sending Midi to the latest qsynth built from fink on the Mac
> and on Ubuntu the qtractor and qsynth from the natty repo. I also tested
> using just the command line version of fluidsynth 1.1.3 on the Mac and I got
> the same CPU problems.
> Thanks
> Ed

Intel or PPC?

There is also a qsynth mac universal binary package at sourceforge, can you please try it as well?

My Mac Mini (intel core2duo) and the usual configuration consumes around 15% CPU (between 10% and 20%) as reported by the activity monitor.

In order to reduce the CPU usage, you may want to set a bigger buffer size (-z, --audio-bufsize=[size]) and/or number of periods (-c, --audio-bufcount=[count]). The default values (64x16) are good for low latency, but you may save some CPU cycles using greater values. The reverb and chorus effects are also very CPU hungry. Please, can you provide details about your fluidsynth settings and system?


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