bluez-alsa: SCO record quality is not great

Hello,

I’m testing recording from two BT headsets. Zebra HS3100 and Plantronics Voyager Legend.

Playback quality is great, but recording is quiet, crackling, and slightly sped up.

I’m using the latest master (24b7300) with and without --enable-debug. Launched as: /usr/bin/bluealsa --syslog -p a2dp-sink -p a2dp-source -p hfp-hf -p hfp-ag -p hsp-hs -p hsp-ag

Any hints would be a appreciated to improve record quality.

If it helps, here are the logs from arecord:

# arecord -v -fS16_LE -r 8000 -Dbluealsa:DEV=00:1B:41:B2:86:9A,PROFILE=sco test.wav
D: src/asound/bluealsa-pcm.c:1312: Getting BlueALSA PCM: CAPTURE 00:1B:41:B2:86:9A sco
D: src/asound/bluealsa-pcm.c:1062: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Setting constraints
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 8000 Hz, Mono
D: src/asound/bluealsa-pcm.c:532: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Initializing HW
D: src/asound/bluealsa-pcm.c:567: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: FIFO buffer size: 32768 frames
D: src/asound/bluealsa-pcm.c:573: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Selected HW buffer: 4 periods x 2000 bytes == 8000 bytes
D: src/asound/bluealsa-pcm.c:600: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Initializing SW
D: src/asound/bluealsa-pcm.c:600: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Initializing SW
D: src/asound/bluealsa-pcm.c:639: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Prepared
D: src/asound/bluealsa-pcm.c:600: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Initializing SW
Plug PCM: BlueALSA PCM: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source
BlueALSA BlueZ device: /org/bluez/hci0/dev_00_1B_41_B2_86_9A
BlueALSA Bluetooth codec: CVSD
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 1000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : GETTIMEOFDAY
  period_step  : 1
  avail_min    : 1000
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 2097152000
D: src/asound/bluealsa-pcm.c:356: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Starting
D: src/asound/bluealsa-pcm.c:226: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Starting IO loop: 7

-- a few seconds later I press Ctrl-C --
^CAborted by signal Interrupt...
arecord: pcm_read:2151: read error: Interrupted system call
D: src/asound/bluealsa-pcm.c:392: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Stopping
D: src/asound/bluealsa-pcm.c:161: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: IO thread cleanup
D: src/asound/bluealsa-pcm.c:592: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Freeing HW
D: src/asound/bluealsa-pcm.c:443: /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source: Closing

And here are the logs from BlueAlsa daemon:

user.debug /usr/bin/bluealsa: src/dbus.c:66: Called: org.bluealsa.PCM1.Open() on /org/bluealsa/hci0/dev_00_1B_41_B2_86_9A/hfpag/source
user.debug /usr/bin/bluealsa: src/ba-transport.c:710: New SCO link: 00:1B:41:B2:86:9A: 24
user.debug /usr/bin/bluealsa: src/hci.c:132: SCO link socket MTU: 24: 180
user.debug /usr/bin/bluealsa: src/ba-transport.c:1145: Starting transport: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/ba-transport.c:293: Created BT socket duplicate: [24]: 25
user.debug /usr/bin/bluealsa: src/ba-transport.c:1462: Created new IO thread [ba-sco-enc]: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/ba-transport.c:293: Created BT socket duplicate: [24]: 26
user.debug /usr/bin/bluealsa: src/ba-transport.c:1462: Created new IO thread [ba-sco-dec]: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/sco.c:229: IO loop: START: sco_cvsd_enc_thread: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/sco.c:297: IO loop: START: sco_cvsd_dec_thread: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/ba-transport.c:1377: PCM resumed: 21
user.debug /usr/bin/bluealsa: src/ba-transport.c:1424: Closing PCM: 21
user.debug /usr/bin/bluealsa: src/ba-transport.c:437: PCM clients check keep-alive: 0 ms
user.debug /usr/bin/bluealsa: src/ba-transport.c:386: Stopping transport: No PCM clients
user.debug /usr/bin/bluealsa: src/ba-transport.c:305: Closing BT socket duplicate [24]: 25
user.debug /usr/bin/bluealsa: src/ba-transport.c:725: Releasing SCO link: 24
user.debug /usr/bin/bluealsa: src/ba-transport.c:1487: Exiting IO thread [ba-sco-enc]: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/ba-transport.c:305: Closing BT socket duplicate [-1]: 26
user.debug /usr/bin/bluealsa: src/sco.c:319: IO loop: EXIT: sco_cvsd_dec_thread: HFP Audio Gateway (CVSD)
user.debug /usr/bin/bluealsa: src/ba-transport.c:1487: Exiting IO thread [ba-sco-dec]: HFP Audio Gateway (CVSD)