Game Detection Service

The GameDetectionService monitors running processes and automatically starts recording when supported games are detected. It uses Windows Management Instrumentation (WMI) events, foreground window hooks, and periodic process scanning.

Overview

Implemented in Backend/Services/GameDetectionService.cs, the service provides:

Automatic game detection from multiple sources (games.json, Steam, EA, Epic, Ubisoft)
WMI-based process monitoring (start/stop events)
Foreground window change detection
Periodic process scanning for games that don’t trigger events
Whitelist and blacklist support
Anti-cheat and launcher filtering

Core Methods

StartAsync

Initializes and starts the game detection service.

public static async void StartAsync()

Behavior:

Initializes game database from games.json
Starts WMI watchers for process creation and deletion
Starts periodic process check timer (runs every 10 seconds)
Runs on a background thread

This method is automatically called by OBSService.InitializeAsync() after OBS initialization completes.

Example

GameDetectionService.StartAsync();

Detection Strategies

The service uses multiple strategies to detect games:

1. Whitelist (Highest Priority)

Games in Settings.Instance.Whitelist are always recorded, regardless of other criteria.

[
  {
    "Name": "My Custom Game",
    "Paths": [
      "C:/Games/MyGame/game.exe",
      "*/MyGame/*.exe"
    ]
  }
]

2. Blacklist (Second Priority)

Games in Settings.Instance.Blacklist are never recorded.

[
  {
    "Name": "Launcher",
    "Paths": [
      "*/Launcher/launcher.exe"
    ]
  }
]

3. Known Games Database

The service checks if the executable path matches entries in games.json:

bool isKnownGame = GameUtils.IsGameExePath(exePath);
string gameName = GameUtils.GetGameNameFromExePath(exePath);

4. Launcher-Based Detection

Automatically detects games from popular launchers: Steam:

Pattern: */steamapps/common/{GameFolder}/*.exe
Resolves game name from .acf manifest files

EA Games:

Pattern: */EA Games/{GameFolder}/*.exe
Uses folder name as game name

Epic Games:

Pattern: */Epic Games/{GameFolder}/*.exe
Resolves game name from manifest JSON files in %ProgramData%/Epic/EpicGamesLauncher/Data/Manifests

Ubisoft:

Pattern: */Ubisoft/{GameFolder}/*.exe
Uses file description from EXE metadata

5. Filtering

The service filters out: System Processes:

Paths starting with C:\Windows\System32\
Paths starting with C:\Windows\SysWOW64\
Paths starting with C:\Program Files\Git\

Blacklisted Path Text:

string[] blacklistedPathTexts = GameUtils.GetBlacklistedPathTexts();
// Example: "crash reporter", "uninstall", "updater"

Anti-Cheat Clients:

string[] blacklistedWords = GameUtils.GetBlacklistedWords();
// Example: "anti-cheat", "launcher", "crash handler"

Checked against file description metadata. Splash Screen Detection: If a known game executable exists in the same folder but differs from the current process, the current process is skipped (likely a splash screen or launcher).

Process Monitoring

WMI Event Watchers

The service uses two WMI watchers: Process Start Watcher:

SELECT * FROM __InstanceCreationEvent WITHIN 1 WHERE TargetInstance isa "Win32_Process"

Triggered when a new process starts. Checks if it’s a recordable game. Process Stop Watcher:

SELECT * FROM __InstanceDeletionEvent WITHIN 1 WHERE TargetInstance isa "Win32_Process"

Triggered when a process exits. Stops recording if it matches the currently recorded game.

Foreground Window Hook

The ForegroundHook subclass monitors foreground window changes:

GameDetectionService.ForegroundHook.Start();

Behavior:

Sets up a Windows event hook for EVENT_SYSTEM_FOREGROUND
Runs on a dedicated STA thread with a message loop
Resets PreventRetryRecording flag when foreground changes
Checks if the new foreground window is a recordable game

The foreground hook runs on a separate thread and must be properly stopped to avoid resource leaks:

GameDetectionService.ForegroundHook.Stop();

Periodic Process Check

A timer runs every 10 seconds to check for games that might not trigger other events:

CheckForGames()

Process:

Verifies the currently recording process is still alive
Gets the foreground window and its process ID
Resolves the executable path
Checks if it should record the game
Starts recording if criteria are met

This timer catches games that launch without triggering WMI events or don’t change the foreground window immediately.

Process Path Resolution

The service uses multiple strategies to resolve process executable paths:

Strategy 1: QueryFullProcessImageName (Preferred)

IntPtr hProcess = OpenProcess(0x1000, false, pid); // PROCESS_QUERY_LIMITED_INFORMATION
QueryFullProcessImageName(hProcess, 0, sb, ref size);

Works for most processes, including elevated ones.

Strategy 2: Process.MainModule

var proc = Process.GetProcessById(pid);
return proc.MainModule.FileName;

Standard .NET approach (may fail for elevated processes).

Strategy 3: GetProcessImageFileName (Device Path)

GetProcessImageFileName(hProcess, sb, out int _);
return DevicePathToDrivePath(sb.ToString());

Converts device paths like \Device\HarddiskVolume1\... to C:\...

Strategy 4: WMI Query (Slowest)

SELECT ExecutablePath FROM Win32_Process WHERE ProcessId = {pid}

Fallback for processes that can’t be accessed via other methods.

Game Name Extraction

The service attempts to extract friendly game names:

private static string ExtractGameName(string exePath)

Priority Order:

games.json lookup: GameUtils.GetGameNameFromExePath(exePath)
Steam ACF lookup: Reads .acf manifest files to find game name
EA Games lookup: Uses folder name after /EA Games/
Epic Games lookup: Reads manifest JSON files for DisplayName
Ubisoft lookup: Reads FileDescription from EXE metadata
Fallback: Uses filename without extension

// Path: C:/Program Files/Steam/steamapps/common/VALORANT/game.exe
// ACF file: steamapps/appmanifest_123456.acf
// Returns: "VALORANT" (from ACF "name" field)

Configuration Properties

PreventRetryRecording

bool

default:"false"

When true, prevents the periodic process check from starting a new recording. Automatically reset when foreground window changes.

Integration with Recording Service

When a game is detected, the service creates a pre-recording state:

Settings.Instance.State.PreRecording = new PreRecording
{
    Game = gameName,
    Status = "Waiting to start",
    CoverImageId = coverImageId,
    Pid = pid,
    Exe = exePath
};

OBSService.StartRecording(gameName, exePath, pid: pid);

Process Lifecycle

Process Start: WMI detects new process
Path Resolution: Resolve executable path using multiple strategies
Game Detection: Check whitelist, blacklist, known games, launchers
Name Extraction: Determine friendly game name
Pre-Recording: Set state and notify frontend
Recording Start: Call OBSService.StartRecording()
Process Stop: WMI detects process exit
Recording Stop: Call OBSService.StopRecording()

Error Handling

The service includes robust error handling:

Path Resolution Failures

If all strategies fail, returns empty string and skips the process.

Access Denied

Elevated processes may not be accessible - uses limited-access APIs (PROCESS_QUERY_LIMITED_INFORMATION).

Process Exited

Handles ArgumentException and InvalidOperationException when process exits during detection.

WMI Exceptions

Catches and logs WMI event handler exceptions to prevent service interruption.

Performance Considerations

WMI Events: Near-instant detection (1-second polling interval)
Foreground Hook: Immediate detection on window change
Process Check: 10-second intervals (low overhead)
Path Resolution: Cached drive mappings for device-to-drive conversion

The service initializes drive mappings once at startup:

InitializeDriveMappings();

This caches \Device\HarddiskVolume1 → C:\ mappings for fast conversion.

Logging

The service provides detailed logging:

[OnProcessStarted] Application started: PID 12345, Path: C:/Games/Game.exe
Detected known game Valorant at C:/Riot Games/.../VALORANT.exe, will record
Game Valorant found in whitelist, will record
Blocked executable with blacklisted path text 'crash reporter': ...
Detected anticheat client for this executable, will not record
Skipping splash.exe - a known game exe exists in 'GameFolder'

Thread Safety

The service uses multiple threads:

Main Thread: Service initialization
Background Thread: WMI event handling
Hook Thread: Foreground window events (STA)
Timer Thread: Periodic process checks

No shared mutable state requires locking - each handler independently checks Settings.Instance.State.

Overview

Core Services

​Overview

​Core Methods

​StartAsync

​Detection Strategies

​1. Whitelist (Highest Priority)

​2. Blacklist (Second Priority)

​3. Known Games Database

​4. Launcher-Based Detection

​5. Filtering

​Process Monitoring

​WMI Event Watchers

​Foreground Window Hook

​Periodic Process Check

​Process Path Resolution

​Strategy 1: QueryFullProcessImageName (Preferred)

​Strategy 2: Process.MainModule

​Strategy 3: GetProcessImageFileName (Device Path)

​Strategy 4: WMI Query (Slowest)

​Game Name Extraction

​Configuration Properties

​Integration with Recording Service

​Process Lifecycle

​Error Handling

​Path Resolution Failures

​Access Denied

​Process Exited

​WMI Exceptions

​Performance Considerations

​Logging

​Thread Safety

Overview

Core Methods

StartAsync

Detection Strategies

1. Whitelist (Highest Priority)

2. Blacklist (Second Priority)

3. Known Games Database

4. Launcher-Based Detection

5. Filtering

Process Monitoring

WMI Event Watchers

Foreground Window Hook

Periodic Process Check

Process Path Resolution

Strategy 1: QueryFullProcessImageName (Preferred)

Strategy 2: Process.MainModule

Strategy 3: GetProcessImageFileName (Device Path)

Strategy 4: WMI Query (Slowest)

Game Name Extraction

Configuration Properties

Integration with Recording Service

Process Lifecycle

Error Handling

Path Resolution Failures

Access Denied

Process Exited

WMI Exceptions

Performance Considerations

Logging

Thread Safety