On Wed, January 31, 2018 15:55, Christian Affolter wrote:
  On 31.01.2018 15:20, Kjetil Matheussen wrote:
  Maybe jack will work if you give it the same
parameters that arecord
 uses. I.e. compare the content of
  /proc/asound/card0/pcm0p/sub0/hw_params (or a similarly
 named file) when running arecord and when running jack.
 Also, maybe it works to record in jack if you change audio from
 "duplex"
 to "capture only". 
 BINGO and thank you so much for this pointer! 
 
 # hw_params during jackd -d alsa -d hw:0
 # jackd -d alsa
 cat /proc/asound/card0/pcm0c/sub0/hw_params
 access: MMAP_INTERLEAVED
 format: S32_LE
 subformat: STD
 channels: 8
 rate: 48000 (48000/1)
 period_size: 1024
 buffer_size: 2048
 
What i wonder is did you see 8 JACK system:capture ports with the above
configuration? It's still confusing that JACK would attach the device
differently. The factor 4 can probably be explained by 8 / 2 channels (?)
or has it do with duplex?.
It could be that the record just took every 4th sample. But why?
For future reference, this could be issued on github with these detailed
debug informations. It's possible that JACK can't do anything about it if
it's driver related. So.. up to you.
 # hw_params during jackd -d alsa -d hw:0 -C -i 2
 cat /proc/asound/card0/pcm0c/sub0/hw_params
 access: MMAP_INTERLEAVED
 format: S32_LE
 subformat: STD
 channels: 2
 rate: 48000 (48000/1)
 period_size: 1024
 buffer_size: 2048