Hello
I am working towards using ALSA for playback and capture on an embedded
platform running Linux. The kernel uses ALSA driver version 1.0.10rc1. I had
manually built and installed ALSA library (v1.0.10) and ALSA utilities
(v1.0.10) for the target platform filesystem. I have a USB audio device
(C-Media) connected to the USB port of the board and it seems to be
successfully successfully detected by the driver.
~ # ls /dev/snd -l
crw-rw---- 1 root root 220, 0 Jan 1 00:00 controlC0
crw-rw---- 1 root root 220, 24 Jan 1 00:00 pcmC0D0c
crw-rw---- 1 root root 220, 16 Jan 1 00:00 pcmC0D0p
crw-rw---- 1 root root 220, 1 Jan 1 00:00 seq
crw-rw---- 1 root root 220, 33 Jan 1 00:00 timer
~ # cat /proc/asound/cards
0 [default ]: USB-Audio - C-Media USB Audio Device
C-Media USB Audio Device at usb-asic-ehci-1.4, full
speed
~ # cat /proc/asound/devices
1: : sequencer
16: [0- 0]: digital audio playback
24: [0- 0]: digital audio capture
0: [0- 0]: ctl
33: : timer
~ # cat /proc/asound/card0/stream0
C-Media USB Audio Device at usb-asic-ehci-1.4, full speed : USB Audio
Playback:
Status: Stop
Interface 1
Altset 1
Format: S16_LE
Channels: 2
Endpoint: 1 OUT (ADAPTIVE)
Rates: 48000, 44100
Capture:
Status: Stop
Interface 2
Altset 1
Format: S16_LE
Channels: 1
Endpoint: 2 IN (ASYNC)
Rates: 48000, 44100
However, when I run ALSA utilities like aplay, arecord or speaker-test, I
observe errors opening the hardware device which may be related to the
configuration on the filesystem.
~ # aplay -l
**** List of PLAYBACK Hardware Devices ****
ALSA lib control.c:817:(snd_ctl_open_noupdate) Invalid CTL hw:0
aplay: device_list:230: control open (0): No such file or directory
aplay: conf.c:3109: snd_config_update_free: Assertion `update->count > 0 &&
update->finfo' failed.
Aborted (core dumped)
~ #
/home/saurav # aplay -D plughw:0,0 winxp.wav
ALSA lib pcm.c:2099:(snd_pcm_open_noupdate) Unknown PCM plughw:0,0
aplay: main:544: audio open error: No such file or directory
/home/saurav #
/home/saurav #
/home/saurav # speaker-test
speaker-test 0.0.8
Playback device is plughw:0,0
Stream parameters are 48000Hz, S16_BE, 1 channels
Using 16 octaves of pink noise
ALSA lib pcm.c:2099:(snd_pcm_open_noupdate) Unknown PCM plughw:0,0
Playback open error: -2,No such file or directory
speaker-test: conf.c:3109: snd_config_update_free: Assertion `update->count > 0
&& update->finfo' failed.
Aborted (core dumped)
/home/saurav #
Are these errors from ALSA utility/library due to the detection of hardware,
ALSA configuration files or something else related to my target device
filesystem?
Thanks in advance for any help. Do let me know if you need any more details.
Best Regards
Saurav
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