30 Jan
2018
30 Jan
'18
1:01 p.m.
On Tue, January 30, 2018 19:46, Christian Affolter wrote:
Hi Thomas,
On 30.01.2018 18:15, Christian Affolter wrote:
now that's an interesting find .. in theory it should not make a
difference if jack uses alsa backend or if you attach via alsa_in but
obviously it *does* make a difference.
40 seconds is the length when played at 12k.
4 x 8 bit also fit into 32 bit. something is fishy.
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