[Jack-Devel] jack2 crackle sound problem on bbb - jack_bufsize?

[Fredrik Olofsson]

dear collected wisdom,
i have a tough problem to solve with jackd messing up my input sound.  it’s a
reoccurring crackling on the input channel that sounds a bit like pulsewave ring
modulation.  i figured out it’s highly dependent on my blocksize settings.
for example:
with -p1024 the distortion starts every 7th minute and lasts for 2min50sec.
with -p512 the distortion sounds slightly different (like with a higher ringmod
freq) and starts every 3min15sec and lasts for ~1min.
with -p256 it appears every 1min45sec and lasts for 40sec.
etc.

after much research i found this...
http://thread.gmane.org/gmane.comp.audio.jackit/28114/focus=28115
and this…
http://music.columbia.edu/pipermail/linux-audio-user/2005-August/025787.html
that i believe describe the same issue.

as suggested in those posts resetting the jack_bufsize makes the distortion go
away.  but only temporarily - it always comes back after exactly the same time!
for now i can let my system reset the buffer after a known time interval, but
that’s a really ugly hack and i’d be happy for suggestions on how to solve this.

below are details of my system.  i compile jack2 from master and it’s all
running under debian wheezy on a beaglebone black.  i use supercollider 3.7 and
a terratec aureon dual usb soundcard.
i’ve also tried with another usb soundcard (C-MEDIA) but then the crackle occurs
on the output instead (and also after longer intervals).  so same issue but
sounds worse.

thank you,
_f


BeagleBoard.org Debian Image 2015-03-01
Linux asdf 3.8.13-bone70 #1 SMP Fri Jan 23 02:15:42 UTC 2015 armv7l GNU/Linux
gcc and g++ version 4.7.2

~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

~$ lsusb
Bus 001 Device 004: ID 0ccd:0077 TerraTec Electronic GmbH Aureon Dual USB

~/jack2$ ./waf configure --alsa
Setting top to                           : /home/debian/jack2 
Setting out to                           : /home/debian/jack2/build 
Checking for 'g++' (C++ compiler)        : /usr/bin/g++ 
Checking for 'gcc' (C compiler)          : /usr/bin/gcc 
Linux detected 
Checking for program 'doxygen'           : not found 
Checking for program 'pkg-config'        : /usr/bin/pkg-config 
Checking for 'alsa' >= 1.0.18            : yes 
Checking for 'libffado' >= 1.999.17      : not found 
Checking for 'libfreebob' >= 1.0.0       : not found 
Checking for 'gtkIOStream' >= 1.4.0      : not found 
Checking for 'eigen3' >= 3.1.2           : not found 
Checking for header windows.h            : not found 
Checking for 'portaudio-2.0' >= 19       : not found 
Checking for header mmsystem.h           : no 
Checking for 'celt' >= 0.11.0            : not found 
Checking for 'celt' >= 0.8.0             : not found 
Checking for 'celt' >= 0.7.0             : not found 
Checking for 'celt' >= 0.5.0             : not found 
Checking for header opus/opus_custom.h   : not found 
Checking for 'opus' >= 0.9.0             : not found 
Checking for 'samplerate' >= 0           : yes 
Checking for 'sndfile' >= 0              : yes 
Checking for library readline            : yes 
Checking for header readline/readline.h  : yes 

==================                      
JACK 1.9.11 svn revision will checked and eventually updated during build
Build with a maximum of 64 JACK clients
Build with a maximum of 768 ports per application
Install prefix                           :  /usr/local 
Library directory                        :  /usr/local/lib 
Drivers directory                        :  /usr/local/lib/jack 
Build debuggable binaries                :  no 
C compiler flags                         :  ['-Wall'] 
C++ compiler flags                       :  ['-Wall'] 
Linker flags                             :  [] 
Build with engine profiling              :  no 
Build with 32/64 bits mixed mode         :  no 
Build standard JACK (jackd)              :  yes 
Build D-Bus JACK (jackdbus)              :  no 
Autostart method                         :  classic 
Build doxygen documentation              :  no 
Enable ALSA driver                       :  yes 
Enable FireWire driver (FFADO)           :  no 
Enable FreeBob driver                    :  no 
Enable IIO driver                        :  no 
Enable Portaudio driver                  :  no 
Enable WinMME driver                     :  no 
Build with CELT                          :  no 
Build Opus netjack2                      :  no 
Build with libsamplerate                 :  yes 
Build with libsndfile                    :  yes 
Build with readline                      :  yes 

~$ tail /etc/security/limits.conf
@audio - memlock 256000
@audio - rtprio 75

~$ sudo jackd -P75 -dalsa -dhw:1,0 -p256 -n3 -r44100 -s &

jackdmp 1.9.11
JACK server starting in realtime mode with priority 75
self-connect-mode is "Don't restrict self connect requests"
creating alsa driver ...
hw:1,0|hw:1,0|256|3|44100|0|0|nomon|swmeter|soft-mode|32bit
configuring for 44100Hz, period = 256 frames (5.8 ms), buffer = 3 periods
ALSA: final selected sample format for capture: 16bit little-endian
ALSA: use 3 periods for capture
ALSA: final selected sample format for playback: 16bit little-endian
ALSA: use 3 periods for playback