Moonlight — Open Source Game Streaming Client

Introduction

Moonlight is an open source implementation of NVIDIA's GameStream protocol that lets you stream games and applications from a powerful PC to almost any device on your network. Originally a reverse-engineering effort of the Shield streaming protocol, it has grown into the go-to client for self-hosted game streaming when paired with Sunshine as the host.

What Moonlight Does

• Streams games and desktop applications from a host PC to clients over a local network or the internet
• Supports up to 4K resolution at 120 fps with HDR on compatible hardware
• Provides hardware-accelerated video decoding on the client for minimal CPU usage
• Works with gamepad, keyboard, and mouse input forwarded to the host with low latency
• Available on Windows, macOS, Linux, iOS, Android, ChromeOS, and Steam Link

Architecture Overview

The host (Sunshine or NVIDIA GameStream) captures the screen using GPU hardware encoders (NVENC, AMF, or VA-API), encodes the video as H.264 or HEVC, and streams it over RTSP to the client. Moonlight decodes the stream using platform-native hardware decoders and renders the frames. Input events are sent back over a low-latency control channel. The entire pipeline is optimized to keep end-to-end latency under 30 ms on a good LAN.

Self-Hosting & Configuration

• Pair with the host by entering the PIN displayed in Moonlight into the host's web UI
• Video settings (resolution, frame rate, bitrate) are configured in Moonlight's settings panel
• For internet streaming, configure port forwarding or use a VPN like Tailscale or ZeroTier
• Audio can be streamed alongside video or kept on the host
• Custom apps and games can be added to the host's app list via Sunshine's web interface

Key Features

• Sub-30 ms latency on a local gigabit network with hardware encoding and decoding
• HDR passthrough for vivid colors on supported displays and GPUs
• Multi-controller support for local co-op gaming on the client device
• Clipboard sharing and remote desktop mode for productivity use
• HEVC and AV1 codec support for better quality at lower bitrates

Comparison with Similar Tools

• Steam Remote Play — Built into Steam; easy setup but limited to Steam library and higher latency
• Parsec — Low-latency cloud gaming service; commercial with a free tier, closed source
• Sunshine — The recommended host companion for Moonlight; open source replacement for NVIDIA GameStream
• NVIDIA GameStream — The original proprietary host; deprecated in favor of Sunshine
• Remote Desktop (RDP/VNC) — General-purpose remote access; not optimized for gaming latency or frame rates

FAQ

Q: Do I need an NVIDIA GPU to use Moonlight? A: No. When paired with Sunshine as the host, Moonlight works with NVIDIA, AMD, and Intel GPUs. The original NVIDIA GameStream required an NVIDIA GPU, but Sunshine removed that limitation.

Q: Can I stream over the internet? A: Yes, but it requires port forwarding or a VPN. A VPN like Tailscale is the simplest approach and avoids exposing ports to the public internet.

Q: What is the difference between Moonlight and Sunshine? A: Moonlight is the client that receives and displays the stream. Sunshine is the host that captures, encodes, and sends the stream. They work together as a pair.

Q: Does Moonlight support mouse and keyboard input? A: Yes. Moonlight forwards mouse, keyboard, and gamepad input to the host. You can use it as a full remote desktop replacement for gaming or productivity.

Sources

• https://github.com/moonlight-stream/moonlight-qt
• https://moonlight-stream.org