Linux and Proton¶

JRTI runs on the native Linux build of KSP and on the Windows build through Proton. Everything works the same as on Windows except recording, which needs ffmpeg set up once.

Which one are you running?¶

Look inside KSP's folder:

Folder	Build
`KSP_Data`	Native Linux
`KSP_x64_Data`	The Windows build, so KSP is running through Proton

What works without setup¶

The web UI, live feeds, layouts, pan and tracking, sound and the Hullcam filters (night vision and the others) all work out of the box. Only recording needs the steps below.

Native Linux¶

Install ffmpeg from your distribution's package manager:

Distribution	Command
Debian, Ubuntu, Linux Mint, Pop!_OS	`sudo apt install ffmpeg`
Arch, Manjaro, EndeavourOS	`sudo pacman -S ffmpeg`
Fedora	`sudo dnf install ffmpeg-free` (hardware encoders and AV1 work; for the full build with libx264, enable RPM Fusion and run `sudo dnf swap ffmpeg-free ffmpeg --allowerasing`)
openSUSE	`sudo zypper install ffmpeg` (the official build has hardware encoders, OpenH264 and AV1 but no libx264; the Packman repository provides the full build)
Anything else	Your package manager's `ffmpeg` package, or the static build below

Start KSP and check the encoders.

The package is not required: a static build works on any distribution, and is the way to go on immutable systems such as SteamOS and the Steam Deck. Follow the Proton steps below. JRTI checks GameData/JustReadTheInstructions/PluginData/ffmpeg/ before the system's ffmpeg.

Proton¶

Windows' encoder (Media Foundation) does not exist under Proton, so JRTI records the way native Linux does, through a Linux build of ffmpeg. Proton runs games inside Steam's container, which cannot run the ffmpeg from your package manager, so use a static build:

Download ffmpeg-...-linux64-gpl-....tar.xz from BtbN's FFmpeg builds.
Extract it into GameData/JustReadTheInstructions/PluginData/ffmpeg/ (the whole folder or just the ffmpeg file).
Start KSP and check the encoders.

Check it worked¶

Open JRTI's settings window in the game (Ctrl + Alt + F8). It lists the encoders it found, for example av1_vaapi, h264_vaapi (ffmpeg). Then open Settings in the web UI and pick a Video codec: only codecs that work on your machine are listed.

If nothing is found, Record stays off and the settings window says why. Under Proton without ffmpeg it tells you to put a Linux build in the PluginData/ffmpeg/ folder.

Which encoder it uses¶

JRTI tries graphics card encoders before CPU encoders, in this order:

Codec	Order
H.264 (default)	`h264_nvenc` → `h264_vaapi` → `h264_qsv` → `h264_vulkan` → `libx264` → `libopenh264`
AV1	`av1_nvenc` → `av1_vaapi` → `av1_qsv` → `av1_vulkan` → `libsvtav1`

In practice NVIDIA cards use NVENC, and AMD and Intel cards use VA-API. What each encoder needs is listed in Recording. To see what your ffmpeg build has:

ffmpeg -hide_banner -encoders | grep -E "264|av1"

Keep H.264 unless you have checked that your whole workflow handles AV1. See Choosing a codec.

Fedora with an AMD graphics card

Fedora's Mesa drivers leave out H.264 and H.265 hardware encoding, so H.264 falls back to the CPU unless you install RPM Fusion's mesa-va-drivers-freeworld. AV1 hardware encoding on supported cards should still work. Intel and NVIDIA cards use their own drivers and are not affected.

Problems¶

Record stays off. The settings window says why. The usual cause is ffmpeg missing, or a copy that cannot run: under Proton the system's ffmpeg does not work, use the static build above.
Only CPU encoders are listed (libx264, libsvtav1). Your graphics driver has no hardware encoder, or your ffmpeg build lacks it. CPU encoding is slower and can drop frames at high resolutions while KSP is running.
The web UI does not open. See Troubleshooting.

Building the mod yourself under Proton is covered in CONTRIBUTING.md.