Sound via 3.5mm jack on Raspberry Pi 4 within container

Product support balenaOS
1

Hi,

I’m trying to setup a simple audio player within my application.
I’ve heard about balena-sound, but I want to integrate some audio into my application, so balena-sound will not help me with this. I’ve used it as an example though!

Starting at the beginning, I’m stuck already. I have an Alpine container (balenalib/raspberrypi4-64-alpine-node:12), where my application is running. I’ve added the alsa-utils package and tried to do the speaker-test via the 3.5mm jack. But not a sound is coming out of my speakers.

Checking with aplay, I’m getting the following output:

$ aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
default:CARD=Headphones
    bcm2835 Headphones, bcm2835 Headphones
    Default Audio Device
sysdefault:CARD=Headphones
    bcm2835 Headphones, bcm2835 Headphones
    Default Audio Device

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

So there is a bcm2835 Headphones card found.
I’ve seen people getting success with using amixer cset numid=3 1, but that command doesn’t succeed. Here’s the output of some amixer commands:

$ amixer cset numid=3 1
amixer: Cannot find the given element from control default

$ amixer contents
numid=2,iface=MIXER,name='Headphone Playback Switch'
  ; type=BOOLEAN,access=rw------,values=1
  : values=on
numid=1,iface=MIXER,name='Headphone Playback Volume'
  ; type=INTEGER,access=rw---R--,values=1,min=-10239,max=400,step=0
  : values=400
  | dBscale-min=-102.39dB,step=0.01dB,mute=1

On other forums, I saw that there should be another card, the HDMI card. But it just shows the headphones.

Some details about the Pi itself:
Raspberry Pi 4 (64-bit image)
BalenaOS 2.73.1+rev1 (development image)
Supervisor v12.4.6

Contents of config.txt

dtoverlay=miniuart-bt
dtoverlay=pi3-miniuart-bt
enable_uart=1
arm_64bit=1
avoid_warnings=1
disable_splash=1
dtparam=i2c_arm=on
dtparam=spi=on
dtparam=audio=on
gpu_mem=16

Container is running privileged, UDEV and dbus are both enabled.

Any help would be welcome!

3

Okay so, skip all that.
Someone moved my Raspberry Pi and the 3.5mm jack was in the wrong Raspberry Pi.
So that wasted some hours of my life :upside_down_face:

4

Hah!
We’ve all been there - no worries!

1 Like