On Saturday, December 3, 2016 1:20:09 PM EST David Klann wrote: > Greetings, > > Long-time Linux user, and relatively new JACK user here. I have built > some audio workstations for the community radio station where I > volunteer (WDRT, Viroqua, WI, US). I recently switched one of the > workstations to use JACK, along with PulseAudio. We use Audacity to edit > audio and we have noticed that the "left" and "right" channels are out > of sync with each other. We have witnessed the "skew" to be as few as > two samples (which is unnoticeable to the ear) to as many as a couple > hundred samples (which sounds a lot like a phase error). > > We performed a lot of troubleshooting, including swapping PCI audio > cards (ESI Juli@, Digigram VX222), disabling JACK, running Audacity on > the same hardware booted from a USB stick and a completely different > Debian environment. I am not *completely* confident, but the likely > culprit seems to be JACK. > > We have recorded audio using jack-record and experienced the same > left-right channel skew. > > Can anyone help point to JACK or OS configuration parameters that we > might look at to get our left and right channels in sync? > > Details: > > OS: Debian Jessie (8.6), up to date (kernel: 3.16.0-4-amd64 #1 SMP > Debian 3.16.36-1+deb8u2 (2016-10-19) x86_64 GNU/Linux) > JACK (jackd2): 1.9.10+20140719git3eb0ae6a~df > PulseAudio: 5.0-13 > ALSA: 1.0.27+1 > CPU: Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz > RAM: 8GB > Audio Cards: ESI Juli@ PCI, Digigram VX222HR PCI > > Thanks for your consideration! > > ~David Klann Hello, this might be a long shot, but maybe not. You mentioned it did this when Jack was disabled, so it seems Jack is not the problem. Look for the LAU thread on Wednesday titled: " [SOLVED] Crackles in audio, drifting intermittent noise etc." I was having very strange phasing problems, although I didn't notice from channel to channel but I wasn't really listening for that. I knew it was hardware related, only that could cause it. My ONLY solution was changing the number of enabled CPU cores, either through my BIOS or through Linux commands such as: echo 0| sudo tee /sys/devices/system/cpu/cpu3/online cat /sys/devices/system/cpu/cpu3/online I found that I must run with just ONE core for the most stability. (I had posted that I found TWO cores were OK but actually further test revealed it was not OK.) So try: echo 0| sudo tee /sys/devices/system/cpu/cpu1/online echo 0| sudo tee /sys/devices/system/cpu/cpu2/online echo 0| sudo tee /sys/devices/system/cpu/cpu3/online cpu0 will always be online. Tim. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
