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

[Christian Affolter]

Hi everyone,

capturing from ALSA capture devices via the Jack2 sound server (1.9.12),
results in too high pitched wav files (they are playing "too fast" and
sound like the "chipmunks"). If I run the same capture directly from the
ALSA devices (without Jack involved), everything sounds as expected
without any problems.

Audio examples:
Capture via jackrec: https://filebin.ca/3pyMxBw8cexQ/test-jackrec.wav
Capture via arecord: https://filebin.ca/3pyOPjcKGym5/test-arecord.wav

The device in question is a "virtual" Axia-ALSA (Livewire+) audio device
on CentOS 7 which operates at a sample rate of 48kHz and a bit depth of
either 16 or 32. As far as I can see, the sample rate and format
detection on the Jack side looks correct. I'm therefore looking for some
guidance on how to further debug this, I most certainly missed something
obvious.

I've also tried to play an mp3 file via mpg123 over jack (without the
involvement of the Alsa device) and record it again with jackrec. This
works and sounds correct.

Here is what I've tried and what the environment looks like:

# Capabilities of the Axia-ALSA device
arecord -D hw:0 --dump-hw-params

Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
HW Params of device "hw:0":
--------------------
ACCESS:  MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT:  S16_LE S32_LE
SUBFORMAT:  STD
SAMPLE_BITS: [16 32]
FRAME_BITS: [16 256]
CHANNELS: [1 8]
RATE: 48000
PERIOD_TIME: (41 1365334)
PERIOD_SIZE: [2 65536]
PERIOD_BYTES: [64 131072]
PERIODS: [1 1024]
BUFFER_TIME: (41 1365334)
BUFFER_SIZE: [2 65536]
BUFFER_BYTES: [64 131072]
TICK_TIME: ALL
--------------------
arecord: set_params:1299: Sample format non available
Available formats:
- S16_LE
- S32_LE


# Capture via arecord directly from the ALSA device (without jackd)
# This works as expected and the WAV file sounds fine
arecord -D hw:0 -c 2 -d 10 -r 48000 -f S32_LE -v /tmp/test-arecord.wav

Recording WAVE '/tmp/test-arecord.wav' : Signed 32 bit Little Endian,
Rate 48000 Hz, Stereo
Hardware PCM card 0 'Axia' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S32_LE
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 32
  buffer_size  : 16384
  period_size  : 4096
  period_time  : 85333
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 4096
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 16384
  silence_threshold: 0
  silence_size : 0
  boundary     : 4611686018427387904
  appl_ptr     : 0
  hw_ptr       : 0


# playing arecord wav (via my local notebook's HDA Intel PCH
# device), sounds correct
aplay test-arecord.wav

Playing WAVE 'test-arecord.wav' : Signed 32 bit Little Endian, Rate
48000 Hz, Stereo



# Starting jackd
# Verbose output at: https://pastebin.com/YzHEGSnR
jackd -d alsa -d hw:0

jackdmp 1.9.12
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2017 Filipe Coelho.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
no message buffer overruns
no message buffer overruns
no message buffer overruns
JACK server starting in realtime mode with priority 20
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 32bit integer little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 32bit integer little-endian
ALSA: use 2 periods for playback


# Capture via jackrec
# This results in a too high pitched WAV file
# Verbose output at: https://pastebin.com/PCnymKLA
jackrec -f /tmp/test-jackrec.wav -d 10 -b 32 system:capture_1
system:capture_2

# playing jackrec wav (via my local notebook's HDA Intel PCH
# device), sounds incorrect
aplay test-jackrec.wav

Playing WAVE 'test-jackrec.wav' : Signed 32 bit Little Endian, Rate
48000 Hz, Stereo


System environment:
Distribution: CentOS 7.4.1708
Kernel:       3.10.0-693.17.1.el7.x86_64
ALSA Utils:   1.1.3
Jackd:        1.9.12

The jackd was rebuilt from Fedora source RPM to be able to test with the
latest version:
https://build.opensuse.org/package/show/home:radiorabe:audio/jack-audio-connection-kit


Many thanks and best regards
Chris