obs-game-stream-plugin/docs/obs-setup.md

OBS setup

Configures OBS Studio on the Windows gaming PC to capture the game, encode with NVENC, and publish via WHIP to the local MediaMTX instance that the OBS script spawns.

Prerequisites:

• OBS Studio 30.0 or newer (WHIP output is built in from 30.x onward).
• You already ran .\scripts\install.ps1 in an elevated PowerShell, so bin\mediamtx.exe exists and the GameStream-UDP-48189 firewall rule is registered (in the disabled state).

1. Load the OBS script

1. OBS -> Tools -> Scripts -> +

2. Select obs-script/game_stream.py from this repo.

3. In the properties panel on the right, set:

   Setting	Value
   MediaMTX binary	<repo>\bin\mediamtx.exe
   MediaMTX config	<repo>\config\mediamtx.yml
   Frontend directory	<repo>\frontend
   Frontend HTTP port	48080 (default)
   Firewall rule name	GameStream-UDP-48189 (must match the rule created by install.ps1)
   Public URL	https://stream.hetherman.cloud
   MediaMTX API URL	http://127.0.0.1:49997

4. Check the Script Log at the bottom - you should see [game_stream] game_stream.py loaded.

2. OBS output settings

Settings -> Output, set Output Mode to Advanced.

Streaming tab

Setting	Value
Audio Encoder	Opus (or FFmpeg AAC if Opus is unavailable - Opus is preferred for WebRTC)
Video Encoder	NVIDIA NVENC HEVC or NVIDIA NVENC H.264

Use H.264 for maximum browser compatibility (all browsers). HEVC works in Safari and recent Chrome but not Firefox - stick with H.264 unless you have a specific reason.

Encoder settings (H.264):

Setting	Value
Rate Control	CBR
Bitrate	8000 Kbps
Keyframe Interval	2 s
Preset	P5 (Quality)
Tuning	Ultra Low Latency
Multipass	Two Passes (Quarter Resolution)
Profile	high
Look-ahead	off
Psycho Visual Tuning	on
GPU	0
Max B-frames	0 (required for low-latency WebRTC)

With a 600 Mbps upload and up to 6 viewers at 8 Mbps each, 8000 Kbps leaves generous headroom. Push to 12000-15000 Kbps if you want higher quality.

Audio tab

Setting	Value
Audio Bitrate	128 Kbps
Sample Rate	48 kHz

3. OBS stream settings

Settings -> Stream

Setting	Value
Service	Custom
Protocol	WHIP
Server	http://localhost:48889/game/whip
Bearer Token	(leave blank)

Save.

4. First stream

1. Click Start Streaming.
2. Check the OBS Script Log - you should see:
   • Firewall rule 'GameStream-UDP-48189' ENABLED
   • MediaMTX started (pid=...)
   • Frontend HTTP server listening on 0.0.0.0:48080
   • Viewers can watch at: https://stream.hetherman.cloud
3. Open https://stream.hetherman.cloud from another device, log in with Authentik, and verify video plays.

5. Stopping

Click Stop Streaming in OBS. The script will:

• Stop the MediaMTX subprocess
• Stop the frontend HTTP server
• Disable the firewall rule (GameStream-UDP-48189 -> disabled)

Verify the firewall state from PowerShell:

Get-NetFirewallRule -DisplayName "GameStream-UDP-48189" | Select-Object Enabled

Should report False while not streaming, True while streaming.

Troubleshooting

• "MediaMTX binary not found" in the script log: the path in the script properties panel is wrong. Re-select it with the file picker.
• OBS cannot connect to WHIP: MediaMTX did not start. Check the script log for the actual reason; most commonly a port conflict on 48889 or 48189 (another process is already using them).
• Viewers see "Stream offline" even after you click Start Streaming:
  • Check that the MediaMTX API returns ready: true: curl http://localhost:49997/v3/paths/get/game
  • Check OBS's own streaming indicator - if it's red, OBS is not actually sending to WHIP. Verify the URL and that the custom service / WHIP protocol is selected.
• Viewers connect but playback freezes after a few seconds: the UDP port path is broken. Verify the firewall rule is enabled (Get-NetFirewallRule), the router port-forward to NPM for UDP 48189 is correct, and the NPM Stream entry points at <PC-LAN-IP>:48189.
• Autoplay is blocked / no audio: browsers start the video muted so autoplay works. There is a "Click to unmute" button in the status bar.