How to name the sound hw device? (USB Microphone, L4T 32.2.3)

Autonomous Machines Jetson & Embedded Systems Jetson Nano
1

Running into a problem in selecting the hardware device for a USB microphone/headphone jack. The problem occurred in both sound recording and display. The device is an AmazonBasic USB Conference Microphone, and it is visible with arecord and aplay. For instance:

arecord -l

**** List of CAPTURE Hardware Devices ****
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 0: ADMAIF1 CIF ADMAIF1-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 1: ADMAIF2 CIF ADMAIF2-1 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 2: ADMAIF3 CIF ADMAIF3-2 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 3: ADMAIF4 CIF ADMAIF4-3 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 4: ADMAIF5 CIF ADMAIF5-4 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 5: ADMAIF6 CIF ADMAIF6-5 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 6: ADMAIF7 CIF ADMAIF7-6 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 7: ADMAIF8 CIF ADMAIF8-7 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 8: ADMAIF9 CIF ADMAIF9-8 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: tegrasndt210ref [tegra-snd-t210ref-mobile-rt565x], device 9: ADMAIF10 CIF ADMAIF10-9 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: Mic [AmazonBasics USB Conference Mic], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

However, if I do

arecord -D hw:2,0 -c 1 -r 16000 -f S16_LE -d 10 cap3.wav

I got error:

Recording WAVE 'cap3.wav' : Signed 16 bit Little Endian, Rate 16000 Hz, Mono
arecord: set_params:1305: Channels count non available

I get the microphone to work by setting up the microphone and headphone as default in system->Sound, and record by

arecord -D 'default' -c 1 -r 16000 -f S16_LE -d 10 cap3.wav

The situation is the same for “aplay” command.

How do I name it if I have to specify the device?

2

Hi,
Please run

nvidia@nvidia-desktop:~$ arecord -D hw:2,0 --dump-hw-params

and see if one channel and 16KHz are supported.

3

Thanks DaneLLL for the info. Here is the output for the command

tmx3@tmx3-jetboxnano1:~/users/tmx3/audio$ arecord -D hw:2,0 --dump-hw-params
Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
HW Params of device "hw:2,0":
--------------------
ACCESS:  MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 32
CHANNELS: 2
RATE: [8000 48000]
PERIOD_TIME: [1000 16384000]
PERIOD_SIZE: [16 131072]
PERIOD_BYTES: [64 524288]
PERIODS: [2 1024]
BUFFER_TIME: (666 32768000]
BUFFER_SIZE: [32 262144]
BUFFER_BYTES: [128 1048576]
TICK_TIME: ALL
--------------------
arecord: set_params:1299: Sample format non available
Available formats:
- S16_LE

Based on the params dump, the speaker mic is actually stereo. In that case, the channel setting should be 2. So my original setting “-c 1” was wrong. The correct on should be

arecord -D hw:2,0 -c 2 -r 16000 -f S16_LE -d 10 cap3.wav

I just tested, it works!