Arch Linux

DoubleR

Member

Registered: 2019-04-24

Posts: 1

[SOLVED] ALSA LIB - snd_pcm_hw_open error: unkown field slave

Hi

I am new to audio programming with alsa. I am using the "Audioinjector octosound card" and after installed it all worked.

Yesterday i was trying the example pcm.c that send a sinus to the channel 1 of the soundcard (https://www.alsa-project.org/alsa-doc/a … ample.html) and it worked well. I had to change some parameters (device name, rate and bit).
Today, after  "shutdown now", it doesen't work anymore.

The error is:

Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Sine wave rate is 440.0000Hz
Using transfer method: write
ALSA lib pcm_hw.c:1789:(_snd_pcm_hw_open) Unknown field slave
Playback open error: Invalid argument

The "Uknown field slave" error appear even if i use aplay or speaker-test command. Honestly, i dont know why this is happening and i didnt change any config file.
With aplay -L or -l I can see my soundcard correctly installed:
pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: audioinjectoroc [audioinjector-octo-soundcard], device 0: AudioInject-HIFI cs42448-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Here u can see my .asound:
pcm.!default {
       type hw
       card 0
        type plug
        slave.pcm "anyChannelCount"
}

ctl.!default {
        type hw
        card 0
}

pcm.anyChannelCount {
    type route
    slave.pcm "hw:0"
    slave.channels 8;
    ttable {
           0.0 1
           1.1 1
           2.2 1
           3.3 1
           4.4 1
           5.5 1
           6.6 1
           7.7 1
    }
}

ctl.anyChannelCount {
    type hw;
    card 0;
}

What's wrong or what i am missing?

Thanks for your help and time

EDIT:
I really dont know why but changing the name to: "plughw:0,0" it works. It seems that he he goes to the salve.pcm table and find hw 0,0 as device 0 channel 0.

Last edited by DoubleR (2019-04-24 10:33:43)