On 08/19/2015 06:30 AM, Herschel Karunaratne wrote:
I am using an ARM board with Ubuntu Linaro 13.04 and Alsa as the sound
and MIDI driver. I have a SF with 13 different instruments and playing
through USB MIDI. As the Fluidsynth starts I use CC 0 7 0.... command
to reduce the volume of all the MIDI channels to zero. When a key is
pressed the MIDI sends Note ON command to all 16 MIDI channels. I
switch ON/OFF instruments by setting the MIDI channel volume 0 or 127
again by using cc command again.
My issue is when I start FS, I get the following warnings,
fluidsynth warning: Requested a period size of 64, got 1024 instead
fluidsynth warning: Requested 16 periods, got 8 instead
When I play 4 notes(up to 4 notes) simultaneously it plays perfectly
but when I press the 5th key (or more) there is a crackling sound like
a buffer underrun and when I release one note (4 again) it plays
perfectly again.
I tried using -c and -z to change the period size but cannot reduce
the period size less than 1024 and cannot increase number of periods
to more than 8.
Any suggestion how this can be fixed?
Regards
Herschel
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Herschel:
On slower machines, FluidSynth/Qsynth works better using JACK (qjackctl).
Another thing that helps on slower machines, is to set the polyphony
down to 64 (rather than the default value of 256).
But there is another change worth trying. I got it from David on this
e-mail list. I have documented it below.
If you're still getting audio drop-outs after having made the foregoing
changes, there is yet another change you can make to prevent them.
This change works on Ubuntu variants, and I don't know if it is
applicable to other Linux distributions.
In the “/etc/security/limits.d/” directory, specific limits are set for
specific users. Each file in that directory corresponds to a user-ID,
and it specifies the limits for that user.
For example, my user-ID is “aere”, and in the “/etc/security/limits.d/”
directory on my system, there is a file named “aere.conf”, which
specifies specific limits (or extra capabilities) for me (user “aere”).
The contents of that file on my system, are as follows:
aere - rtprio 85
aere - memlock unlimited
Note that each line starts with my user-ID (“aere”).
You need to create a similar file (for your user-ID) in that directory.
You can do that by running your system's terminal program, and
cut-and-pasting the line highlighted below into it, and transmitting
that line. If you don't know how to use (or don't have) the “vi” editor,
substitute the name of the editor you use (such as “leafpad” or “gedit”)
in place of “vi” in the line below. Also, substitute your user-id in
place of “userid”.
sudo vi /etc/security/limits.d/userid.conf
After transmitting the above line, you'll have to enter your sign-in
password (and the cursor won't advance while you do it).
After successfully entering your password, an empty file will be
displayed in the editor. Enter the following two lines, substituting
your user-ID in place of “userid” in the two lines you enter:
userid - rtprio 85
userid - memlock unlimited
After doing-so, save the file. You have to log-off and sign back in (or
possibly even reboot) before the change takes effect.
With the above change in my system, I can successfully run Qsynth on a
very slow (450 megahertz) machine.
So do take the time to try this configuration change. It can make a big
difference.
--
Sincerely,
Aere
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