SlipStream

Low-latency remote desktop streaming over WebRTC with hardware-first video encode and decode paths.

Installer workflow, command-line arguments, client UI features, D3D11 sync, and configuration/auth setup are now documented.

Overview

SlipStream captures the Windows desktop with the Windows Graphics Capture API and encodes frames in real time with FFmpeg-backed encoder paths. It prefers hardware encoders on NVIDIA, Intel, and AMD GPUs, but can fall back to software encoders when the selected codec is not available in hardware. Video, system audio, control traffic, input, and microphone audio are carried over WebRTC data channels with DTLS transport from the browser/libdatachannel stack. The browser client renders decoded frames with WebGL2, uses WebCodecs for video and audio decode, supports software decode fallback when hardware decode is unavailable, and can send microphone audio upstream with WebCodecs AudioEncoder. The server runs as an elevated Windows tray application and can also be installed with a scheduled task for boot-time startup.

Architecture

+------------------------------------------------------------------------------+
|                              SERVER (Windows)                                |
+------------------------------------------------------------------------------+
|  Screen Capture         Encoder             WebRTC              Audio        |
|  +--------------+    +--------------+    +----------------+    +----------+  |
|  | WGC API      |--->| HW + SW      |--->| Data Channel   |<-->| WASAPI   |  |
|  | D3D11 Fence  |    | FFmpeg Enc   |    | libdatachannel |    | Opus     |  |
|  | 6-tex pool   |    | AV1/H265/264 |    | 5 channels     |    | 96 kbps  |  |
|  +--------------+    +--------------+    +----------------+    +----------+  |
|                                                 |                  |         |
|                                                 |            +----------+    |
|                                                 |            | VB-Cable |    |
|                                                 |            | Playback |    |
|                                                 |            +----------+    |
|                          +----------------------+----------------------+     |
|                          |       HTTPS Server (port 443)               |     |
|                          |    cpp-httplib + OpenSSL                     |     |
|                          |    JWT Auth + Rate Limiting                  |     |
|                          +----------------------+----------------------+     |
+---------------------------------------------+--------------------------------+
                                              |
                          WebRTC (UDP/TCP 50000-50127)
                                              |
+---------------------------------------------+--------------------------------+
|                              CLIENT (Browser)                                |
+------------------------------------------------------------------------------+
|  +--------------+    +--------------+    +--------------+    +----------+    |
|  | VideoDecoder |--->| WebGL2       |    | AudioDecoder |--->| Worklet  |    |
|  | HW or SW     |    | Letterbox    |    | Opus         |    | RingBuf  |    |
|  +--------------+    +--------------+    +--------------+    +----------+    |
|                                                                    |         |
|  +--------------+                                            +----------+    |
|  | AudioEncoder |<-------------------------------------------|  Mic     |    |
|  | Opus 32kbps  |                                            | Capture  |    |
|  +--------------+                                            +----------+    |
|                                                                              |
|  Input Handler -----> Mouse/Keyboard -----> Data Channel -----> Server       |
+------------------------------------------------------------------------------+

Requirements

Server

Component	Requirement
OS	Windows 10/11 64-bit
GPU	NVIDIA, Intel, or AMD GPU recommended for hardware encode; software encode fallback is available
IDE	Visual Studio 2022 with C++20 Desktop workload
Package Manager	vcpkg
Microphone Output	VB-Cable optional (`CABLE Input` preferred), default render fallback supported

Client

Component	Requirement
Browser	Modern browser with WebRTC DataChannel support; Chromium-based browsers are recommended for best WebCodecs coverage
APIs	WebRTC, WebCodecs (VideoDecoder, AudioDecoder, AudioEncoder, AudioData), WebGL2, AudioWorklet, Clipboard API

Quick Start

1. Install vcpkg

git clone https://github.com/microsoft/vcpkg.git C:\vcpkg
cd C:\vcpkg
.\bootstrap-vcpkg.bat
.\vcpkg integrate install

2. Build

cmake -S . -B build -A x64 -DCMAKE_TOOLCHAIN_FILE="C:/vcpkg/scripts/buildsystems/vcpkg.cmake"
cmake --build build --config Release --target SlipStream

Output: build\bin\Release\SlipStream.exe

3. Run

build\bin\Release\SlipStream.exe

Optional debug logging:

build\bin\Release\SlipStream.exe --debug

On first run:

Prompts for username (3-32 alphanumeric characters, underscores, hyphens)
Prompts for password (8-128 characters with at least one letter and one digit)
Generates self-signed SSL certificate (server.crt, server.key) in %APPDATA%\SlipStream
Saves hashed credentials to %APPDATA%\SlipStream\auth.json
Generates JWT secret to %APPDATA%\SlipStream\jwt_secret.dat
Creates log file at %APPDATA%\SlipStream\slipstream.log
Requests elevation on launch for capture/input features (requireAdministrator manifest)
Hides console to system tray

4. Connect

Open browser to https://<HOST_IP>:443 and log in with your credentials.

At startup, SlipStream prints:

Local URL (https://localhost:443)
All detected non-loopback LAN IPv4 Network URLs

Note: Self-signed certificate will trigger a browser warning. Click through to proceed.

Network Configuration

Port	Protocol	Purpose
443	TCP	HTTPS server and WebRTC signaling
50000-50127	UDP/TCP	WebRTC data transport, ICE checks, and ICE-TCP fallback
1900	UDP (outbound)	UPnP SSDP discovery for automatic router mapping
5351	UDP (outbound)	PCP/NAT-PMP mapping requests and lease renewals to the default gateway

ICE Configuration

Parameter	Value
ICE TCP	Enabled on host as a fallback; UDP remains preferred
ICE Candidate Pool	4
Bundle Policy	max-bundle
RTCP Mux Policy	require

STUN Servers

stun:stun.l.google.com:19302
stun:stun1.l.google.com:19302
stun:stun2.l.google.com:19302
stun:stun3.l.google.com:19302
stun:stun4.l.google.com:19302
stun:stun.cloudflare.com:3478
stun:stun.services.mozilla.com:3478
stun:global.stun.twilio.com:3478

NAT Traversal Notes

SlipStream does not bundle a TURN server. For the best chance of direct WAN connectivity without TURN:

Prefer forwarding UDP 50000-50127 to the host.
If either side is on a network that filters UDP aggressively, also forward TCP 50000-50127 so ICE-TCP candidates can be reached.
SlipStream now attempts consumer-router auto-mapping on the host with UPnP, then PCP, then NAT-PMP.
Automatic mapping targets TCP 443 for signaling, UDP 50000-50127 for WebRTC, and TCP 50000-50127 when ICE-TCP fallback is enabled.
Automatic mapping also sends outbound router-control traffic on UDP 1900 for UPnP discovery and UDP 5351 for PCP/NAT-PMP requests.
If you do not want SlipStream to create or renew router mappings automatically, set SLIPSTREAM_ENABLE_PORT_MAPPING=0 before launch.
To change the requested router-mapping lease, set SLIPSTREAM_PORTMAP_LEASE_SECONDS to a value between 120 and 86400 before launch.
Manual forwarding is still useful when the router does not support these protocols, when the router blocks them by policy, or when you want a permanent mapping instead of a renewable lease.

Firewall

netsh advfirewall firewall add rule name="SlipStream HTTPS" dir=in action=allow protocol=tcp localport=443
netsh advfirewall firewall add rule name="SlipStream WebRTC UDP" dir=in action=allow protocol=udp localport=50000-50127
netsh advfirewall firewall add rule name="SlipStream WebRTC TCP" dir=in action=allow protocol=tcp localport=50000-50127

If outbound firewalling is enabled on the host, also allow UDP 1900 to the local network for UPnP discovery and UDP 5351 to the default gateway for PCP/NAT-PMP.

Security

Password Storage

Parameter	Value
Algorithm	PBKDF2-HMAC-SHA256
Iterations	600,000
Salt	16 bytes (random)
Key Length	32 bytes

Passwords are never stored in plain text. Only the salt and derived hash are saved in %APPDATA%\SlipStream\auth.json.

Rate Limiting

Threshold	Action
5 failed attempts in 15 min	30-minute IP lockout
Successful login	Clears attempt counter

JWT Sessions

Parameter	Value
Algorithm	HS256
Issuer	slipstream
Expiry	24 hours
Storage	HttpOnly, Secure, SameSite=Strict cookie

SSL Certificates

Auto-generated on first run:

2048-bit RSA key
X.509 v3 with SHA-256 signature
10-year validity (3,650 days)
Subject: C=US, O=SlipStream, CN=localhost
Subject Alt Names include localhost, 127.0.0.1, host DNS name, and detected LAN IPv4 addresses
Extensions: CA:FALSE, keyUsage: digitalSignature, keyEncipherment, extKeyUsage: serverAuth

If you previously generated certificates, delete %APPDATA%\SlipStream\server.crt and %APPDATA%\SlipStream\server.key to regenerate with updated SANs.

To use custom certificates, replace %APPDATA%\SlipStream\server.crt and %APPDATA%\SlipStream\server.key before starting.

Security Headers

Header	Value
X-Content-Type-Options	nosniff
X-Frame-Options	DENY
Referrer-Policy	no-referrer

API Endpoints

Endpoint	Method	Auth	Description
`/`	GET	No	Web client HTML
`/styles.css`	GET	No	Stylesheet
`/js/*.js`	GET	No	JavaScript modules
`/api/auth`	POST	No	Login with `{username, password}`
`/api/session`	GET	Cookie	Validate current session
`/api/logout`	POST	No	Clear session cookie
`/api/offer`	POST	Cookie	WebRTC SDP offer exchange

Video Pipeline

Capture

Component	Detail
API	Windows Graphics Capture (WGC)
Texture Pool	6 textures with D3D11 fence sync
Frame Buffer	4-frame ring buffer with generation tracking
Cursor	Optional capture in stream
Border	Disabled (if OS supports)

GPU Vendor Detection

The encoder automatically detects the GPU vendor and selects the appropriate encoder:

Vendor ID	Vendor	Encoder
0x10DE	NVIDIA	NVENC
0x8086	Intel	QSV
0x1002	AMD	AMF

If the primary GPU's encoder path fails, SlipStream probes other vendor-specific hardware encoders and then software encoders for the active codec.

Encoding

Setting	H.264	H.265	AV1
NVIDIA	h264_nvenc	hevc_nvenc	av1_nvenc
Intel	h264_qsv	hevc_qsv	av1_qsv
AMD	h264_amf	hevc_amf	av1_amf

Software fallback encoders are also supported when available:

Codec	Software Fallback Order
H.264	libx264
H.265	libx265
AV1	libsvtav1, libaom-av1, librav1e

NVIDIA NVENC Configuration

Setting	Value
Preset	P2
Tune	Ultra-low latency
Rate Control	VBR
CQ Level	Dynamic by codec / resolution / FPS (base 25 H.264, 28 H.265, 31 AV1)
Zero Latency	Enabled
Lookahead	Disabled
Surfaces	3

Intel QSV Configuration

Setting	Value
Preset	veryfast
Look Ahead	Disabled
Async Depth	1
Low Power	Enabled
Global Quality	Dynamic by codec / resolution / FPS (base 25 H.264, 28 H.265, 31 AV1)
Forced IDR	Enabled

AMD AMF Configuration

Setting	Value
Usage	Ultra-low latency
Quality	Balanced
Rate Control	VBR latency
Header Insertion	GOP
QP	Dynamic by codec / resolution / FPS (base 25 H.264, 28 H.265, 31 AV1)

Bitrate Formula: bitrate is codec-aware and uses an effective-FPS curve.

AV1: max(6,000,000, 0.112 × width × height × effectiveFps)
H.265: max(6,000,000, 0.138 × width × height × effectiveFps)
H.264: max(6,000,000, 0.165 × width × height × effectiveFps)

effectiveFps = fps for fps <= 60, 60 + 2/3 × (fps - 60) for 61-90, and 80 + floor((fps - 90) / 3) above 90 FPS.

For all codecs, maxrate is clamped to at least the target bitrate and otherwise set to 115% of target bitrate.

Transport

Parameter	Value
Chunk Size	1,400 bytes max
Output: `build\bin\Release\SlipStream.exe`
Data Payload	Up to 1,345 bytes per video packet

3. Installer Build

To create a Windows installer (with scheduled task, firewall rules, and shortcuts):

build_installer_release.bat

Creates build\SlipStream-1.0.0-Release-Setup.exe using Inno Setup. See SlipStream.iss for installer script details.

For debug builds:

build_installer_debug.bat

Creates build\SlipStream-1.0.0-Debug-Setup.exe (launches with --debug).

build\bin\Release\SlipStream.exe [--debug] [--trace] [--force-software]

Command-line arguments:

--debug: Enables debug logging
--trace: Enables verbose trace output
--force-software: Forces software encoding for all codecs

Forward Error Correction (FEC)

Video Packet Header (55 bytes)

Offset	Size	Field	Description
0	8	timestamp	Capture timestamp (microseconds)
24	8	enqueueTimestamp	Timestamp when packetization begins
32	4	encodeTimeUs	Encode duration (microseconds)
36	4	frameId	Frame sequence number
40	4	frameSize	Encoded frame size in bytes
44	2	chunkIndex	Chunk index (data: chunk number, FEC: group number)
46	2	totalChunks	Number of data chunks
48	2	chunkBytes	Payload bytes in this packet
50	2	dataChunkSize	Nominal data-chunk size
52	1	frameType	1=keyframe, 0=delta
53	1	packetType	0=data, 1=FEC parity
54	1	fecGroupSize	Effective FEC group size for this frame

Audio Pipeline (Server to Client)

Capture

Parameter	Value
API	WASAPI Loopback
Mode	Shared
Sample Rate	48,000 Hz (resampled if system differs)
Channels	Stereo (max 2)
Frame Duration	10 ms (480 samples)

Encoding

Parameter	Value
Codec	Opus
Application	Restricted Low Delay
Bitrate	96 kbps
Complexity	3
Signal Type	Music
FEC	Disabled
DTX	Disabled

Transport

Parameter	Value
Audio Buffer	128 KB threshold
Max Queue	6 packets (WebRTC send queue), 4 packets capture queue
Delivery	Unordered, maxRetransmits=0
FEC	XOR parity packet every 10 audio packets

Audio Packet Header (24 bytes)

Offset	Size	Field	Description
0	4	magic	0x41554449 ("AUDI")
4	8	timestamp	Capture timestamp
12	4	packetId	Monotonic packet sequence
16	2	samples	Sample count (data packets only)
18	2	dataLength	Payload size
20	1	packetType	0=data, 1=FEC parity
21	1	fecGroupSize	FEC group size (currently 10)
22	2	reserved	Reserved (0)

Client Playback

Component	Detail
Decoder	AudioDecoder (WebCodecs)
Processor	AudioWorklet with ring buffer
Ring Buffer Capacity	24,000 samples (500 ms)
Prebuffer Threshold	1,920 samples (40 ms)
Target Buffer	2,880 samples (60 ms)
Max Buffer	5,760 samples (120 ms)
Underrun Adaptation	After 4 consecutive underruns, increases target by 480 samples (10 ms)
Health Adjustment	Every 2 seconds, reduces target by 240 samples (5 ms) if buffer > 90 ms

Microphone Pipeline (Client to Server)

Client Capture

Parameter	Value
API	MediaDevices.getUserMedia
Sample Rate	48,000 Hz
Channels	Mono
Frame Duration	10 ms (480 samples)
Processing	Echo cancellation, noise suppression, auto gain

Client Encoding

Parameter	Value
Codec	Opus (via WebCodecs AudioEncoder)
Application	VoIP
Bitrate	32 kbps
Complexity	5
Signal Type	Voice
Frame Duration	10 ms

Transport

Parameter	Value
Delivery	Unordered, maxRetransmits=0
Max Queue	20 packets
FEC	XOR parity packet every 10 mic packets

Microphone Packet Header (24 bytes)

Offset	Size	Field	Description
0	4	magic	0x4D494344 ("MICD")
4	8	timestamp	Capture timestamp
12	4	packetId	Monotonic packet sequence
16	2	samples	Sample count (data packets only)
18	2	dataLength	Payload size
20	1	packetType	0=data, 1=FEC parity
21	1	fecGroupSize	FEC group size (currently 10)
22	2	reserved	Reserved (0)

Server Playback

Component	Detail
Output Device	VB-Cable Input preferred (`CABLE Input`)
Decoder	Opus (libopus)
Resampling	Speex polyphase resampler (quality 4) if device rate differs
Fallback	Default audio endpoint if VB-Cable unavailable

Input Protocol

Mouse Move Absolute (12 bytes)

Offset	Size	Field
0	4	magic (0x4D4F5645)
4	4	x (float 0.0-1.0)
8	4	y (float 0.0-1.0)

Mouse Move Relative (8 bytes)

Offset	Size	Field
0	4	magic (0x4D4F5652)
4	2	dx (int16)
6	2	dy (int16)

Mouse Button (6 bytes)

Offset	Size	Field
0	4	magic (0x4D42544E)
4	1	button (0-4)
5	1	action (1=down, 0=up)

Button mapping: 0=left, 1=right, 2=middle, 3=X1, 4=X2

Mouse Wheel (8 bytes)

Offset	Size	Field
0	4	magic (0x4D57484C)
4	2	deltaX (int16)
6	2	deltaY (int16)

Keyboard (10 bytes)

Offset	Size	Field
0	4	magic (0x4B455920)
4	2	keyCode (JS keyCode)
6	2	scanCode
8	1	action (1=down, 0=up)
9	1	modifiers (currently sent by client, ignored by server)

Modifiers: Ctrl=1, Alt=2, Shift=4, Meta=8

Clipboard Data (8 + N bytes)

Offset	Size	Field
0	4	magic (0x434C4950)
4	4	length
8	N	UTF-8 text (max 1MB)

Cursor Shape (5 bytes)

Offset	Size	Field
0	4	magic (0x43555253)
4	1	cursorType (0-13, 255)

Cursor types: 0=default, 1=text, 2=pointer, 3=wait, 4=progress, 5=crosshair, 6=move, 7=ew-resize, 8=ns-resize, 9=nwse-resize, 10=nesw-resize, 11=not-allowed, 12=help, 13=none, 255=custom

Rate Limits (Server-Enforced)

Type	Max per Second
Mouse moves	500
Clicks	50
Keystrokes	100

Blocked Inputs

Ctrl+Alt+Delete (blocked server-side)
Windows key and ContextMenu (not captured by client without fullscreen keyboard lock)

Control Messages

Message	Magic	Size	Description
PING	0x504E4750	16/24	Clock synchronization
HOST_INFO	0x484F5354	7	Host display refresh rate plus host flags
FPS_SET	0x46505343	7	Set target frame rate
FPS_ACK	0x46505341	7	Frame rate acknowledgment
CODEC_SET	0x434F4443	5	Set video codec
CODEC_ACK	0x434F4441	5	Codec acknowledgment
CODEC_CAPS	0x434F4350	5	Server codec capabilities bitmask
SOFTWARE_ENCODE	0x4E455753	5	Enable or disable software encoding on the host
ENCODER_INFO	0x49434E45	Variable	Active codec, host encode flags, and encoder name
REQUEST_KEY	0x4B455952	4	Request keyframe
MONITOR_LIST	0x4D4F4E4C	Variable	Monitor enumeration
MONITOR_SET	0x4D4F4E53	5	Switch monitor
AUDIO_ENABLE	0x41554445	5	Enable/disable audio streaming
MIC_ENABLE	0x4D494345	5	Enable/disable mic streaming
CURSOR_CAPTURE	0x43555243	5	Toggle cursor capture in video
CLIPBOARD_GET	0x434C4754	4	Request clipboard contents
CLIPBOARD_DATA	0x434C4950	8+N	Clipboard text transfer
VERSION	0x56455253	Variable	Host version string
KICKED	0x4B49434B	4	Client disconnected by server

Codec Capabilities (CODEC_CAPS)

The server sends a bitmask indicating supported codecs:

Bit 0 (0x01): AV1 supported
Bit 1 (0x02): H.265 supported
Bit 2 (0x04): H.264 supported

The client uses this to enable/disable codec options in the UI.

Host Flags

HOST_INFO and ENCODER_INFO expose host-side encode state bits:

Bit 0 (0x01): software encoding currently active
Bit 1 (0x02): software encoding forced because the selected codec has no hardware encoder available

WebRTC Data Channels

Channel	Ordered	MaxRetransmits	Purpose
control	Yes	3	Commands, ping/pong, monitor list
video	No	0	Video frame chunks
audio	No	0	Audio packets
input	Yes	3	Mouse/keyboard events
mic	No	0	Microphone audio packets

Client Modules

File	Purpose
`constants.js`	Protocol message types, codec definitions, data channel configs, tuning constants
`state.js`	Shared state, logging, codec detection, clock sync, metrics collection
`network.js`	WebRTC signaling, data channel management, FEC handling, reconnection logic
`renderer.js`	WebGL2 rendering with aspect ratio letterboxing
`media.js`	VideoDecoder, AudioDecoder, keyframe retry, and AudioWorklet plumbing
`input.js`	Mouse/keyboard capture, RAF batching, pointer lock
`ui.js`	Settings panel, fullscreen, software encode/decode toggles, tabbed mode, stats overlay
`mic.js`	Microphone capture, AudioEncoder, packet transmission
`auth.js`	Authentication flow, session validation, login/logout UI
`protocol.js`	Message construction, keyframe throttling, FEC recovery, adaptive quality
`audio-worklet.js`	Audio output AudioWorklet processor with adaptive ring buffer
`mic-worklet.js`	Microphone input AudioWorklet processor (10 ms frame buffering)

Clock Synchronization

Parameter	Value
Ping interval	200 ms
Sample count	8
Offset calculation	Median filter
RTT estimation	Median of samples
RTT validity range	0–5,000,000 µs
Minimum samples for valid sync	2

Reconnection

Parameter	Value
Max reconnection attempts	3
Backoff	`min(1000 × attempt, 5000)` ms
Server busy (503) retries	5
Server busy backoff	`min(1000 × (retry + 1), 5000)` ms
First-frame watchdog	Warning logged after 3,000 ms
After max failures	Clears session, returns to login screen

Adaptive Quality

Triggered by sustained decode pressure (≥ 12 consecutive high-queue events, cooldown 6,000 ms between adjustments):

FPS reduction — If FPS > 30, reduce to 30 (or 24 if currently ≤ 45)
Codec fallback — AV1 → H.265 → H.264 (one-time per session)

Frame Handling

Parameter	Value
Max in-flight frames	64 (minimum), scaled by `ceil(fps × 900 / 1000) + 12`
Frame timeout	900 ms
Max frame age (jitter)	50 ms
Decode queue limit	6 frames

UI Features

Settings Panel

Access by clicking the right edge of the screen:

Logout - Disconnect and clear session
Fullscreen - Enter fullscreen with keyboard lock (Escape captured)
Audio - Toggle system audio playback
Mic - Toggle microphone transmission to server
Monitor - Switch between displays
Frame Rate - 15/30/60/120/144 or custom (1-240)
Codec - AV1, H.265, or H.264 (shows HW/SW status and host availability)
Software Encode - Prefer software encoding on the host when available; forced on when hardware encode is unavailable for the active codec
Software Decode - Prefer software decoding on the client; forced on when the browser lacks hardware decode for the active codec
Tabbed Mode - Monitor tabs at top of screen
Debug Stats - Real-time performance overlay
Relative Mouse - Pointer lock mode for gaming
Clipboard Sync - Enable Ctrl+C/V synchronization

Tabbed Mode

When enabled, displays a tab strip showing all monitors with:

Monitor name (EDID friendly name or user rename)
Primary indicator (star icon)
Click to switch monitors
Double-click active tab to rename monitor label (saved in browser localStorage)

Debug Stats Overlay

Real-time metrics display organized into sections:

UI Features

Section	Metrics

Server Components

Process priority class: ABOVE_NORMAL_PRIORITY_CLASS

System Tray

Feature	Detail
Behavior	Console window hides to system tray on startup and when minimized
Context Menu	Right-click tray icon: Open SlipStream (restore console) or Exit SlipStream (shutdown)
Console Close	Disabled (grayed out) to prevent accidental termination
Icon	Loaded from executable resource, fallback to default system icon

Server Header Files

File	Purpose
`host_app.hpp`	Main application class, session orchestration
`common.hpp`	Types, auth utilities, monitor enumeration, SSL generation
`app_support.hpp`	App setup, credential prompts, auth helpers
`logging.hpp`	Logging infrastructure
`protocol.hpp`	Protocol message definitions and magic values
`utils.hpp`	Utility functions
`d3d_sync.hpp`	D3D11 fence synchronization (ID3D11Fence)
`audio_resampler.hpp`	Speex-based audio resampler
`capture.hpp`	Screen capture with WGC, texture pool, frame slot
`encoder.hpp`	Video encoding via FFmpeg (hardware-first with software fallback)
`webrtc.hpp`	WebRTC server, data channels, packet headers
`audio.hpp`	WASAPI audio capture + Opus encoding, mic playback
`input.hpp`	Input handling, keyboard/mouse injection, clipboard
`tray.hpp`	System tray icon and context menu

Dependencies

Managed via vcpkg (vcpkg.json):

Package	Purpose
libdatachannel	WebRTC implementation
cpp-httplib[openssl]	HTTPS server
nlohmann-json	JSON parsing
opus	Audio encoding/decoding
openssl	Cryptography, SSL/TLS
ffmpeg[nvcodec,avcodec]	Hardware and software video encoding support
jwt-cpp	JWT token handling
speexdsp	Audio resampling

The build also links FFmpeg's avutil and swscale components for frame handling and software encode paths.

Building

Standard Build

cmake -S . -B build -A x64 -DCMAKE_TOOLCHAIN_FILE="C:/vcpkg/scripts/buildsystems/vcpkg.cmake"
cmake --build build --config Release --target SlipStream

Standard Run

build\bin\Release\SlipStream.exe

The executable is built with a requireAdministrator manifest, so Windows will prompt for elevation when it starts.

Installer Build

Requires Inno Setup 6.3+.

build_installer_release.bat

Creates build\SlipStream-1.0.0-Release-Setup.exe.

The installer offers:

Windows Firewall exception (program-based, inbound + outbound)
Startup scheduled task (runs as SYSTEM before login)
Desktop shortcut

On uninstall:

Removes firewall rules and scheduled task
Deletes %APPDATA%\SlipStream data files (auth, certs, JWT secret)

Installer Build (Debug)

build_installer_debug.bat

Creates build\SlipStream-1.0.0-Debug-Setup.exe and configures shortcuts/startup launch with:

SlipStream.exe --debug

File Structure

SlipStream/
├── include/
│   └── host/
│       ├── host_app.hpp          # Main application class
│       ├── core/
│       │   ├── common.hpp        # Common includes, types, auth utilities
│       │   ├── app_support.hpp   # App setup/auth helpers
│       │   ├── logging.hpp       # Logging infrastructure
│       │   ├── protocol.hpp      # Protocol message definitions
│       │   ├── utils.hpp         # Utility functions
│       │   ├── audio_resampler.hpp # Speex audio resampler
│       │   └── d3d_sync.hpp      # D3D11 fence synchronization
│       ├── io/
│       │   ├── tray.hpp          # System tray declarations
│       │   └── input.hpp         # Input handling + clipboard
│       ├── media/
│       │   ├── capture.hpp       # Screen capture with WGC
│       │   ├── encoder.hpp       # Video encoding (hardware-first with software fallback)
│       │   └── audio.hpp         # WASAPI audio capture + Opus + mic playback
│       └── net/
│           └── webrtc.hpp        # WebRTC server declarations
├── src/
│   ├── main.cpp                  # Application entry point
│   ├── version.rc                # Windows version resource
│   └── host/
│       ├── host_app.cpp          # Application orchestration
│       ├── core/
│       │   ├── common.cpp        # Auth/SSL/shared runtime implementations
│       │   └── app_support.cpp   # App setup/auth/helpers
│       ├── io/
│       │   ├── tray.cpp          # System tray integration
│       │   └── input.cpp         # Input injection/clipboard
│       ├── media/
│       │   ├── capture.cpp       # Screen capture pipeline
│       │   ├── encoder.cpp       # Video encoder pipeline
│       │   └── audio.cpp         # System audio capture + mic playback
│       └── net/
│           └── webrtc.cpp        # WebRTC server implementation
├── client/
│   ├── index.html                # Web client HTML
│   ├── styles.css                # Stylesheet
│   └── js/
│       ├── constants.js          # Protocol constants, codec definitions
│       ├── state.js              # Shared state and metrics
│       ├── network.js            # WebRTC signaling, protocol, and reconnection
│       ├── renderer.js           # WebGL2 rendering
│       ├── media.js              # Video/audio decoding and playback pipeline
│       ├── input.js              # Input capture
│       ├── ui.js                 # UI controls
│       ├── mic.js                # Microphone capture and encoding
│       ├── auth.js               # Authentication flow
│       ├── protocol.js           # Message construction, FEC recovery
│       ├── audio-worklet.js      # Audio output worklet processor
│       └── mic-worklet.js        # Microphone input worklet processor
├── vcpkg.json                    # Dependencies
├── CMakeLists.txt                # Build configuration
├── build_installer_release.bat   # Release installer builder
├── build_installer_debug.bat     # Debug installer builder (--debug launch)
├── SlipStream.iss                # Inno Setup installer script
├── LICENSE.md                    # Styled license text
└── Installer-LICENSE.txt         # Installer license text

Microphone Setup (VB-Cable)

To enable client microphone audio on the server:

Install VB-Cable Virtual Audio Device
The server attempts to detect CABLE Input as the output device
Configure your target application to use CABLE Output as its microphone input

If VB-Cable is not installed, SlipStream falls back to the default audio render endpoint.

Troubleshooting

Problem	Solution
vcpkg not found	Set `VCPKG_ROOT` environment variable or install to `C:\vcpkg`
No hardware encoder	SlipStream can fall back to software encode for supported codecs; expect higher CPU usage and lower headroom
Connection refused	Check firewall for TCP 443 and UDP/TCP 50000-50127
Black screen	Wait for keyframe; verify codec compatibility and channel readiness
No audio	Click "Enable" in settings panel after connecting
Mic not working	Ensure browser has microphone permission and supports `AudioEncoder` plus `AudioData`
Input not working	Click the video canvas to capture input focus
Certificate warning	Expected with self-signed certificate, click proceed
Kicked message	Another client connected (single client only)
Monitor switch issues	Frames from previous monitor generations are automatically discarded
Codec grayed out	Either the client browser or the host encoder probe does not support that codec
Software encode forced	The selected codec has no hardware encoder path on the host
Software decode forced	The browser has no hardware decoder for the selected codec

Known Limitations

Windows server only
Single client connection (new client kicks existing)
No custom cursor bitmap sync (standard cursor type sync only)
WebGL2 and WebCodecs are required on the client
Client microphone uplink requires browser support for AudioEncoder and AudioData
Software encode and decode fallbacks work, but they increase CPU load and can reduce latency headroom

Data Storage

All persistent data is stored in %APPDATA%\SlipStream\:

File	Contents
`auth.json`	Username, password hash (PBKDF2), salt
`jwt_secret.dat`	32-byte HS256 secret (64 hex characters)
`server.crt`	Self-signed X.509 certificate
`server.key`	RSA 2048-bit private key
`slipstream.log`	Application log file

Codec Support Detection

Server-Side

The server probes for encoder support on startup:

Detects primary GPU vendor (NVIDIA/Intel/AMD)
Tests each codec (AV1, H.265, H.264) with the vendor's encoder
Falls back to other hardware vendors if the detected vendor path is unavailable
Falls back to software encoders when no hardware path is available for a codec
Sends codec capabilities, host flags, and active encoder information to the client

Client-Side

The client automatically detects codec support on connection:

Tests hardware acceleration for each codec (AV1, H.265, H.264)
Falls back to software decoding when hardware decode is unavailable or user-selected
Intersects browser support with server codec capabilities
Forces software decode when the selected codec has no hardware decoder in the browser
Surfaces codec availability plus software encode/decode state in the UI

License

Business Source License (Personal-Online / No-Company) v1.1

Personal use permitted. Commercial use requires separate license.

Styled/readable version: LICENSE.md
Installer-rendered copy: Installer-LICENSE.txt

Name		Name	Last commit message	Last commit date
Latest commit History 27 Commits
client		client
include/host		include/host
src		src
.gitignore		.gitignore
CMakeLists.txt		CMakeLists.txt
Installer-LICENSE.txt		Installer-LICENSE.txt
LICENSE.md		LICENSE.md
README.MD		README.MD
SlipStream.ico		SlipStream.ico
SlipStream.iss		SlipStream.iss
build_installer_debug.bat		build_installer_debug.bat
build_installer_release.bat		build_installer_release.bat
vcpkg.json		vcpkg.json

Folders and files

Latest commit

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SlipStream

Overview

Architecture

Requirements

Server

Client

Quick Start

1. Install vcpkg

2. Build

3. Run

4. Connect

Network Configuration

ICE Configuration

STUN Servers

NAT Traversal Notes

Firewall

Security

Password Storage

Rate Limiting

JWT Sessions

SSL Certificates

Security Headers

API Endpoints

Video Pipeline

Capture

GPU Vendor Detection

Encoding

NVIDIA NVENC Configuration

Intel QSV Configuration

AMD AMF Configuration

Transport

3. Installer Build

Forward Error Correction (FEC)

Video Packet Header (55 bytes)

Audio Pipeline (Server to Client)

Capture

Encoding

Transport

Audio Packet Header (24 bytes)

Client Playback

Microphone Pipeline (Client to Server)

Client Capture

Client Encoding

Transport

Microphone Packet Header (24 bytes)

Server Playback

Input Protocol

Mouse Move Absolute (12 bytes)

Mouse Move Relative (8 bytes)

Mouse Button (6 bytes)

Mouse Wheel (8 bytes)

Keyboard (10 bytes)

Clipboard Data (8 + N bytes)

Cursor Shape (5 bytes)

Rate Limits (Server-Enforced)

Blocked Inputs

Control Messages

Codec Capabilities (CODEC_CAPS)

Host Flags

WebRTC Data Channels

Client Modules

Clock Synchronization

Reconnection

Adaptive Quality

Frame Handling

UI Features

Settings Panel

Tabbed Mode

Debug Stats Overlay

UI Features

Server Components

System Tray

Server Header Files

Dependencies

Building

Standard Build

Packages