diff --git a/pages/webrtc.md b/pages/webrtc.md new file mode 100644 index 0000000..5b5a574 --- /dev/null +++ b/pages/webrtc.md @@ -0,0 +1,47 @@ +# WebRTC +This is a new alternative video transfer mode available for Raspberry Pi 4 users with an HDMI-CSI bridge. +It uses H.264 encoding instead of MJPEG and provides significantly less traffic consumption. + +# How to use +If you use an OS image built after 2021.06.10, this mode will be available to you by default. +If you are upgrading to an older version of the OS, you will need to manually enable the WebRTC gateway: +``` +# systemctl enable --now kvmd-janus +``` +Then restart the Web UI and then in the System menu you will see the video mode switch. + +# Subtleties +The MJPEG video stream uses the same HTTP connection that you use to download the web interface. +This means that for remote access, you just need to forward ports 80 and 443 on your router. + +In contrast, WebRTC is a completely different way of transmitting video. +It uses a P2P connection and UDP. This reduces network load, but makes it difficult to configure +- the server needs to know your network configuration in order to use it correctly. + +To implement this, the Pi-KVM checks which of the network interfaces is used for the default gateway, +and also tries to find out your external address using the Google [STUN](https://en.wikipedia.org/wiki/STUN) server. +This is necessary when using [Tailscale](tailscale.md) or so that you can connect to your Pi-KVM from the external Internet, +since simply forwarding ports 80 and 443 for WebRTC is not enough - it requires a direct connection. + +If you don't like using Google (it was chosen as the default for reliability reasons) for this purpose, +you can choose [any other STUN server](https://www.voip-info.org/stun/) at your discretion, or start your own. +Use `/etc/kvmd/override.yaml` to this: +```yaml +janus: + stun: + host: stun.stunprotocol.org + port: 3478 +``` +And restart `systemctl restart kvmd-janus`. + +# KVMD-Janus vs. KVMD-Janus-Static +[Janus](https://janus.conf.meetecho.com) is a WebRTC gateway that is used to transmit the [uStreamer](https://github.com/pikvm/ustreamer) video. +KVMD-Janus is a wrapper around it, configuring and monitoring changes in the network configuration. This is suitable for most users. +However, if your Pi-KVM is not connected to the Internet and/or you want to use a custom Janus configuration, +then you should use the `kvmd-janus-static` service instead. You should first change the Janus configuration yourself. +You can find it in `/etc/kvmd/janus/janus.jcfg`. +``` +# systemctl disable --now kvmd-janus +... +# systemctl enable --now kvmd-janus-static +```