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I am working on a python program that I am having some issues with. When the user presses a button a video starts playing. I need the audio to come from the analog jack. It works perfectly when I run it from the terminal or in thonny.

The problem started when I tried to autorun it. I set it up to autorun with /etc/rc.local. It starts correctly, but there is no audio from the VLC player. I am using os.system("amixer sset 'Master' 100%") to set the volume and in my log I get the error amixer: Unable to find simple control 'Master',0. I tried adding os.system("amixer scontrols") to get a little more information, and I got the following: Simple mixer control 'HDMI',0 "Master" isn't mentioned there like it is when I run that command from a terminal.

So what is different here? Why is HDMI audio output my only option when starting from rc.local? I have tried starting with and without sudo and that made no difference.

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  • Because the audio out is just like video out -- there's only one for the system, and things that run in the background (such as those started from rc.local) don't automatically get to access it. That said, I don't have the solution for this (but I am sure there is one).
    – goldilocks ♦
    Commented Feb 14, 2022 at 22:08
  • I'm sure you know that rc.local has been deprecated. I assume "autorun" means "start at boot"?? If so, maybe try another method for auto-starting - a systemd unit, or cron?
    – Seamus
    Commented Feb 15, 2022 at 17:47
  • I did try cron, and it behaved exactly the same way. I am going to try another way tomorrow and see how it goes.
    – Ryan Absher
    Commented Feb 16, 2022 at 5:11

1 Answer 1

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I still don't understand why the other methods weren't working, but I solved the problem by starting the script from ~/.bashrc. It works perfectly now.

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    .bashrc is NOT intended to run scripts. It is run each time a non-login interactive shell is started and is used to configure the shell.
    – Milliways
    Commented Feb 18, 2022 at 23:01

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