# Switching audio between usb DAC and hdmi

**URL:** https://dietpi.com/forum/t/switching-audio-between-usb-dac-and-hdmi/4970
**Category:** General Discussion
**Created:** [11 February 2021 14:34 UTC](https://dietpi.com/forum/t/switching-audio-between-usb-dac-and-hdmi/4970 "2021-02-11T14:34:49Z")
**Posts on this page:** 1
**Showing post:** 4

<div class="post-metadata">

### Author: ![Jappe](https://dietpi.com/forum/user_avatar/dietpi.com/jappe/32/1788_2.png) [@Jappe](https://dietpi.com/forum/u/Jappe)
#### Post date: [27 January 2022 00:30 UTC](https://dietpi.com/forum/t/switching-audio-between-usb-dac-and-hdmi/4970/4 "2022-01-27T00:30:23Z")

</div>

The changes you make in dietpi-config are stored at

```nohighlight
/boot/dietpi.txt

```

there is a line:

```nohighlight
# Sound card
CONFIG_SOUNDCARD=SOMETHING

```

For HDMI output it is: “CONFIG\_SOUNDCARD=rpi-bcm2835-hdmi”  
For USB dac it is: “CONFIG\_SOUNDCARD=usb-dac”

I guess you could write a script to change that line and reboot your Pi, bc you have to reboot to make the change happen.  
  
  
Sometimes you have to use the auto-conversion plugin if you don’t get sound with your USB DAC, but idk where this config is stored, you can enable it also in dietpi-config. (see [https://dietpi.com/forum/t/no-audio-from-usb-dac/4996/1](https://dietpi.com/forum/t/no-audio-from-usb-dac/4996/1))  
  
  
The script “HDMItoUSB.sh” could look something like:

```nohighlight
 #!/bin/bash
 # script to change from HDMI to USB sound
sed -i 's/rpi-bcm2835-hdmi/usb-dac/g' /boot/dietpi.txt
echo "Soundcard changed from HDMI to USB"
echo "machine will reboot in 5 seconds"
sleep 5
reboot

```

to run the script:

```nohighlight
sudo path/to/script/HDMItoUSB.sh

```

To change from USB to HDMI you just have to change

```nohighlight
sed -i 's/rpi-bcm2835-hdmi/usb-dac/g' /boot/dietpi.txt

```

to

```nohighlight
sed -i 's/usb-dac/rpi-bcm2835-hdmi/g' /boot/dietpi.txt

```

You could even check which soundcard is activated right now and change to the other one, done in one script:

```nohighlight
#!/bin/bash
if grep -q CONFIG_SOUNDCARD=rpi-bcm2835-hdmi "/boot/dietpi.txt"; then
    sed -i 's/rpi-bcm2835-hdmi/usb-dac/g' /boot/dietpi.txt
    echo "Soundcard changed from HDMI to USB"
    echo "machine will reboot in 5 seconds"
    sleep 5
    reboot
else
    sed -i 's/usb-dac/rpi-bcm2835-hdmi/g' /boot/dietpi.txt
    echo "Soundcard changed from USB to HDMI"
    echo "machine will reboot in 5 seconds"
    sleep 5
    reboot
fi

```

I think you have to run the script with root permissions to make changes in /boot/ and to be able to reboot.

**These are just theoretical thoughts and this has to be tested! I’m quite new to Linux and scripting stuff and I do not take legal responsibility for anything written here 😉**  
  
  
**ADDENDUM:**  
You can also output the sound through HDMI and USB simultaneously, says this thread at stackexchange:  
[https://raspberrypi.stackexchange.com/questions/55593/output-sound-through-hdmi-and-usb-sound-card](https://raspberrypi.stackexchange.com/questions/55593/output-sound-through-hdmi-and-usb-sound-card)

---

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