Audio from 3.5mm jack after 2nd HDMI connected

[pneumoniastadium]

My set-up is currently Raspberry Pi Model 4 connected through HDMI ports to a TV (HDMI-1) and a projector (HDMI-2). I have the 3.5mm audio jack connected to/speakers.

When all is as described above I cannot get audio from the 3.5mm jack. I can get audio from each HDMI device without issue as both have internal speakers.

After trying different configurations, I have found that I get audio from the 3.5mm jack when HDMI-2 (projector) is disconnected and pi rebooted, so that only HDMI-1 is connected.

I have tried

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sudo amixer cset numid=3 1

without success as i get this returned:

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amixer: Cannot find the given element from control default

I was having these issues and some others relating to my display when using, Raspian (even tried forcing audio through 3.5mm using the raspi-config utility) so I switched from Raspian to Ubuntu-mate. I had the same audio issue in both operating systems. I am currently running Ubuntu Mate.

i have also tried -

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sudo apt-get install --reinstall alsa-base pulseaudio

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sudo alsa force-reload

I have tried testing speakers using ubuntu-mate's graphical sound settings, hardware tab - does not work.
I used alsamixer to ensure that the headphones volume was turned up to full and not muted.

I have tried Google and I have not found a solution. I am new to Linux and Raspberry Pi.


Thanks for your help.

[pneumoniastadium]

bump.

[KenT2]

The method of selecting audio device has changed recently

https://www.raspberrypi.org/blog/latest ... -may-2020/

The new alsa devices can be obtained from this code which I use for mplayer

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                    if self.mplayer_audio in ('hdmi','hdmi0'):
                        driver_option=' -ao alsa:device=plughw=b1.0 '
                    elif self.mplayer_audio == 'hdmi1':
                        driver_option=' -ao alsa:device=plughw=b2.0 '
                    elif self.mplayer_audio in ('alsa','USB'):
                        driver_option=' -ao alsa:device=plughw=Device.0 '
                    elif self.mplayer_audio in ('local','A/V'):
                        driver_option=' -ao alsa:device=plughw=Headphones.0 '