DeskStream

Low-latency Windows → Android and Apple-silicon macOS screen streaming over LAN WiFi. No cloud, no account, no virtual display drivers — the PC mirrors its screen to your phone, tablet, or Mac at 1080p60 with a target glass-to-glass latency under 50 ms.

Built by studying what breaks in Sunshine/Moonlight, Parsec, spacedesk, Steam Link, Miracast, and Chromecast, and designing those failure modes out. See docs/ARCHITECTURE.md for the rationale and docs/PROTOCOL.md for the wire protocol.

Layout

• server/ — Windows server, C#/.NET 8. DXGI Desktop Duplication → GPU NV12 convert → Media Foundation hardware H.264 for NVIDIA/AMD/Intel → UDP with XOR FEC, plus WASAPI system-audio loopback. The experimental direct-NVENC path is opt-in.
• android/ — Android client (Kotlin, minSdk 26). UDP receive + FEC → MediaCodec async low-latency decode → SurfaceView; PCM audio → low-latency AudioTrack. No network jitter buffer. Touch controls the PC mouse, while Bluetooth/USB gamepads forward as virtual Xbox 360 controllers on the PC.
• macos/ — native AppKit client for Apple silicon (macOS 13+). Hardware H.264 display, bounded PCM playback, Keychain pairing, LAN discovery, reconnect/stall recovery, and foreground mouse, full physical-keyboard, and up-to-four-gamepad forwarding with rumble.
• switch/ — Nintendo Switch homebrew client (C++, SDL2, libnx). UDP receive + FEC -> FFmpeg low-latency H.264 software decode -> SDL2 YUV Texture; PCM audio -> low-latency SDL2 Queued Audio; Joy-Con / Pro Controllers are mapped and forwarded as virtual Xbox 360 controllers.
• docs/ — architecture and normative protocol spec.

Quick start

PC (Windows 10/11, a GPU with an H.264 hardware encoder):

1. Install the .NET 8 SDK.
2. cd server && dotnet run -c Release
3. Allow the firewall prompt (or pre-allow TCP 47801, UDP 47800/47802/47803 on private networks).
4. Optional for gamepad forwarding: install the official ViGEmBus 1.22 driver, then restart DeskStream. Video and audio work without it.
5. A web dashboard runs at http://127.0.0.1:47810/ — pairing PIN, live stats, stream restart, and the default quality (Native / 720p). --web-lan exposes it to the LAN (unauthenticated — it shows the PIN), --no-web disables it.
6. To run DeskStream automatically like a service: DeskStreamer.Server.exe --install-autostart registers a logon Scheduled Task that starts the server headless in your session (console output, including the PIN, goes to deskstream.log, while application diagnostics go to deskstream.app.log; manage it from the web dashboard). --uninstall-autostart removes it. A true session-0 Windows service cannot capture the desktop, so this is deliberately a user-session autostart.
7. Optional: cap the encoder target with --max-bitrate-kbps 12000 on congested WiFi (default 20000; minimum 2000). FEC, packet headers, and PCM audio add wire overhead.

Android (8.0+):

1. Open android/ in Android Studio, run on your device.
2. Make sure the phone is on the same WiFi as the PC (5 GHz strongly recommended).
3. Your PC appears in the list — tap it, type the 6-digit PIN shown in the PC console once. After that it auto-connects.
4. In a stream, Hide removes every overlay. Hold three fingers for 600 ms, press Back, or press F11 on a hardware keyboard to restore controls without clicking the host.

macOS (13+, Apple silicon):

1. cd macos && make app using Apple's Command Line Tools.
2. Open build/DeskStream.app; select the discovered PC or enter its LAN address.
3. Pair once with the server PIN. Click the video for direct pointer control, or choose Capture Input for relative game input. Control-Option-Escape releases capture.

Nintendo Switch (Homebrew-enabled console):

1. Make sure you have the official devkitPro toolchain and the switch-dev packages installed.
2. cd switch && make to compile the app.
3. Copy DeskStream.nro to the /switch/DeskStream/ folder on your SD card.
4. Launch the Switch homebrew menu, start the DeskStream client, and select/pair your server.

Why it's fast

• Present-driven GPU capture; the frame never touches the CPU before the encoder.
• Hardware H.264 tuned for latency: CBR, no B-frames, ~1-frame VBV, IDR only on demand.
• Media Foundation hardware encoding is the stable default for NVIDIA, AMD, and Intel GPUs. The direct NVIDIA NVENC ultra-low-latency path is available only with DESKSTREAM_ENCODER=nvenc while it receives broader hardware validation.
• Custom UDP transport: ≤1200-byte packets, forward error correction instead of retransmission, stale frames dropped rather than queued.
• Android decodes straight to the screen surface in async low-latency mode; frames render the moment they decode — there is no buffer anywhere that can grow.
• PC system audio uses fixed 5 ms PCM blocks and non-blocking Android playback. Audio is negotiated separately, so it can fail or be muted without interrupting video.
• Physical Android controllers forward complete state snapshots at up to 120 Hz over UDP, appear to Windows games as Xbox 360 controllers, and receive rumble feedback.
• Android touch offers touchpad and direct-pointer modes. Motion/scroll use newest-wins UDP; ordered mouse buttons use the authenticated TCP control channel and are released on stop.
• The native macOS client displays H.264 immediately through AVFoundation's hardware path, forwards window-focused USB-HID keyboard positions as Windows scan codes, and reuses the same authenticated mouse/gamepad transports without system-wide input permissions.
• Clock-synchronized p95 pipeline telemetry, a media heartbeat, UDP re-punching, bounded pools/queues, and automatic stream restart keep long sessions from accumulating delay.
• Closed-loop bitrate adaptation so WiFi congestion degrades quality, not latency.
• Optional 720p60 mode downscales on the server GPU before encoding and uses a 10 Mbps client ceiling — fewer pixels and packets to encode, send, and decode on constrained networks/devices.