[Jack-Devel] Capture problems with jack2 on Axia-Alsa device

Christian Affolter c.affolter at purplehaze.ch
Tue Jan 30 19:46:40 CET 2018


Hi Thomas,

On 30.01.2018 18:15, Christian Affolter wrote:
> On 30.01.2018 16:23, Christian Affolter wrote:
>>> the alsa device could be the issue. you could try to start a dummy jack
>>> and add the alsa device with alsa_in to see if it makes a difference.

This seems to work, the audio gets captured (and can be played)
correctly. Here is what I did:

# Start jackd with the dummy backend
jackd -d dummy

# Add the alsa device via alsa_in
alsa_in -d hw:0 -c 2


# Capture via jack_capture
jack_capture -b 32 -c 2 -d 10 -fn /tmp/test-jack_capture.wav \
             -p alsa_in:capture_1 -p alsa_in:capture_2

# Capture via jackrec
jackrec -f /tmp/test-jackrec.wav -d 10 -b 32 alsa_in:capture_1
alsa_in:capture_2


What I also observed is the fact, that capturing 10 seconds
(jack_capture -d 10 ...) directly from the "-d alsa" jackd takes around
40 seconds (real 0m40.457s) vs. 10 seconds (as one would expect) with
the "-d dummy" jackd (real 0m10.339s)

So I guess we're one step closer.


Thanks a lot for your help
Chris



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