+++
title = "Streaming camera output trough UDP"
date = 2024-11-14

[taxonomies]
categories = ["Linux"]

[extra]
author = "Emil Miler"
+++

I had an interesting assignment to set up a low-latency video stream from a camera to a TV screen on the third floor of a building for a short event. I came up with a simple solution: streaming it directly over UDP using OBS and capturing the stream with MPV.

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## Intro

The event took place on a stage that needed to be streamed to two screens -- one in the lobby on the ground floor and another deep inside the third floor. The audio team provided a clean audio mix directly to my camera’s audio mixer.

The building, located in the old town of Prague, had a complicated floor plan, as you might imagine. Connecting to the ground floor screen was straightforward with a direct HDMI link, but reaching the third floor was more challenging without an HDMI-to-Ethernet extender, which I didn’t have.

![x210](x210.jpg)

My solution was to lay a UTP cable from the TV on the third floor to my laptop with an HDMI capture card, configure direct routing, and stream from OBS to a client that would output the video and audio over HDMI to the TV.

## Server setup

First I set up the network:

```sh
ip a add 192.168.66.1/24 dev eth0
ip route add 192.168.66.2 dev eth0
```

The OBS part was a little tricky. I am sure this can be highly optimized.

![OBS Settings](obs-settings.png)

## Client setup

Again, static adress is needed, but no routes have to be defined this time.

```sh
ip a add 192.168.66.2/24 dev eth0
```

The stream can then by captured with MPV:

```
mpv --no-cache udp://@0.0.0.0:8081
```

![Client](client.jpg)

It does have some latency, but since the TV was hidden deep in the building, it was not a big issue. I might try using something like [UltraGrid](http://www.ultragrid.cz/) in the future.