pikvm/docs/audio.md

PiKVM V3+ Audio

This feature allows you to receive audio over an HDMI cable and transmit it to the browser in WebRTC mode.

!!! warning * This is only supported by PiKVM V3+ devices right now. This may or may not work on other CSI devices as most have a hw defect. * Please note the feature is experimental. Nothing will explode for you, but something may not work. Please report about problems here (preferred) or here. * KVM switches may or may not work, we currently do not have a list of what works due to the feature being new/experimental. * MIC support is not supported at this time, it may be supported in the future. * USB Dongles do NOT support sound, there is no plans to make this work in the future.

!!! info PiKVM V4 has enabled this feature by default.

Preparing

1. Make sure that you have not removed the jumpers related to audio (4) on the V3 board and have not deleted or commented out the dtoverlay=tc358743-audio line in /boot/config.txt. Return everything as it was, if you changed it. For V4 you can skip this step.

2. Update the OS:

   # rw
   # pacman -Syu
   

3. Edit /etc/kvmd/janus/janus.plugin.ustreamer.jcfg and add the following lines at the end:

   audio: {
       device = "hw:0,0"
       tc358743 = "/dev/kvmd-video"
   }
   

4. Enable the basic audio in the EDID:

   # kvmd-edidconf --set-audio=yes
   

5. Reboot the device:

   # reboot
   

6. Your host will detect the possibility of audio output via HDMI. Mac OS usually connects automatically, Windows requires manual indication, Linux will require a ritual shamanic dance. In any case, make sure that the audio is output via HDMI on your host. PiKVM supports stereo mode with any standard bits and frequencies like 32/44.1/48 kHz with 16/24 bit.

7. Open the PiKVM Web UI. Click the System menu and switch the video mode to H.264 / WebRTC. After that, the volume slider will appear under the switch. Increase it to the maximum and have fun.

!!! warning * After the page is reloaded, the audio slider will be reset. This is a technical limitation in all browsers to avoid annoying audio ads. * If something doesn't work, check the log: journalctl -u kvmd-janus. * Try a different browser, try and clear browser cache before reporting issues. * Unplug the hdmi cable and plug back in, either from the PiKVM end and or the target end. * Please report about problems here (preferred) or here.