Troubleshooting: headphone audio unavailable after unplugging HDMI

[kreativer-stuhlgang]

First and foremost thank you for the great project!

I run 2.2 - 305325d - master (classic edition) on a raspi 3 Raspbian GNU/Linux 10 (buster).

I setup and installed everything with a connected HDMI screen. Once my setup was working as wanted I unplugged the HDMI and wired up everything headless in another room. There I didn't connect the HDMI and powered it up - no sound at all...

Took me a while to figure out that I have to have the HDMI screen connected during the boot process to get the audio headphone jack working! Of course now I don't want to power it down anymore and just keep it running...

How can I change the boot routine to make the RPi-Jukebox run headless?
I tried to change the raspi-config to solely use the headphone jack - no changes.

Any other ideas ? Thank you for your comments on this issue!

[MiczFlor]

I think. I think. I think: if you unplug the HDMI the audio device number changes. Usually that looks something like this:

$ cat /proc/asound/modules
0 snd_bcm2835
1 snd_usb_audio

Have a look here how to change the audio device number after installing with HDMI sound, which might have created the wrong device number.
https://github.com/MiczFlor/RPi-Jukebox-RFID/wiki/Troubleshooting-FAQ#a-audio-never-worked

[s-martin]

The problem is that if you plug in a HDMI monitor an additional sound output is added and the index changes.
This bothering behavior was introduced, when Raspberry Pi separated headphones jack and HDMI into two different devices in May 2020:

https://github.com/MiczFlor/RPi-Jukebox-RFID/wiki/Troubleshooting-FAQ#raspberry-pi-update-may-2020-broke-my-audio

Workaround: use the box during configuration the same way you want to use it later operational, i.e. don't attach a HDMI monitor, if you don't want to use one later.
Then configure Phoniebox the way the link @MiczFlor provided describes.

[kreativer-stuhlgang]

Thank you MiczFlor and s-martin for your comments.
I get the following numbering:
$ cat /proc/asound/modules

0 snd_bcm2835
1 snd_bcm2835

Why do I get it twice as 0 and 1? Could this produce a mixup?

have tried to edit /etc/asound.conf to:

pcm.!default {
    type hw
    card 0
}
ctl.!default {
    type hw
    card 0
}

after rebooting twice it still works with just the headphone jack. so no HDMI needed anymore! Thank you guys!