IRSDKSharper 1.0.1

IRSDKSharper

Alternative C# implementation of the iRacing SDK. I created this project because I was frustrated with the performance and features of IRSDKSharp.

How to use it

Here is an example basic project to demonstrate how to set up and use IRSDKSharper.

public partial class MainWindow : Window
{
    private IRSDKSharper irsdkSharper;

    public MainWindow()
    {
        InitializeComponent();

        // create an instance of IRSDKSharper
        irsdkSharper = new IRSDKSharper();

        // hook up our event handlers
        irsdkSharper.OnException += OnException;
        irsdkSharper.OnConnected += OnConnected;
        irsdkSharper.OnDisconnected += OnDisconnected;
        irsdkSharper.OnSessionInfo += OnSessionInfo;
        irsdkSharper.OnTelemetryData += OnTelemetryData;

        // this means fire the OnTelemetryData event every 30 data frames (2 times a second)
        irsdkSharper.UpdateInterval = 30; 

        // lets go!
        irsdkSharper.Start();
    }

    private void Window_Closing( object sender, CancelEventArgs e )
    {
        irsdkSharper.Stop();
    }

    private void OnException( Exception exception )
    {
        Debug.Log( "OnException() fired!" );
    }

    private void OnConnected()
    {
        Debug.Log( "OnConnected() fired!" );
    }

    private void OnDisconnected()
    {
        Debug.Log( "OnDisconnected() fired!" );
    }

    private void OnSessionInfo()
    {
        var trackName = irsdkSharper.Data.SessionInfo.WeekendInfo.TrackName;

        Debug.Log( $"OnSessionInfo fired! Track name is {trackName}." );
    }

    private void OnTelemetryData()
    {
        var lapDistPct = irsdkSharper.Data.GetFloat( "CarIdxLapDistPct", 5 );

        Debug.Log( $"OnTelemetryData fired! Lap dist pct for the 6th car in the array is {lapDistPct}." );
    }

IRSDKSharper Class

Methods

void Start()

IRSDKSharper will create a new connection loop background task. This connection loop will wait for the iRacing simulator to load and start broadcasting telemetry data. Once telemetry data starts pouring in, IRSDKSharper will terminate the connection loop background task, and create two new background tasks¹. The first new background task handles session information updates, and the second new background task handles telemetry data updates². You can check IsStarted to see if Start has already been called. An exception will be thrown if you try to call Start while IsStarted is true.

void Stop()

IRSDKSharper will terminate all background tasks and clean up everything. The IsStarted property will become false. Do not call Stop from within any of the event handlers (it will deadlock). An exception will be thrown if you try to call Stop while IsStarted is false.

Simulator Remote Control

There are several functions you can use to remotely control the iRacing simulator. These functions control the iRacing simulator by posting broadcast messages the iRacing simulator window.

CamSwitchPos( IRacingSdkEnum.CamSwitchMode camSwitchMode, int carPosition, int group, int camera )
CamSwitchNum( IRacingSdkEnum.CamSwitchMode camSwitchMode, int carNumberRaw, int group, int camera )
CamSetState( IRacingSdkEnum.CameraState cameraState )
ReplaySetPlaySpeed( int speed, bool slowMotion )
ReplaySetPlayPosition( IRacingSdkEnum.RpyPosMode rpyPosMode, int frameNumber )
ReplaySearch( IRacingSdkEnum.RpySrchMode rpySrchMode )
ReplaySetState( IRacingSdkEnum.RpyStateMode rpyStateMode )
ReloadTextures( IRacingSdkEnum.ReloadTexturesMode reloadTexturesMode, int carIdx )
ChatComand( IRacingSdkEnum.ChatCommandMode chatCommandMode, int subCommand )
PitCommand( IRacingSdkEnum.PitCommandMode pitCommandMode, int parameter )
TelemCommand( IRacingSdkEnum.TelemCommandMode telemCommandMode )
FFBCommand( IRacingSdkEnum.FFBCommandMode ffbCommandMode, float value )
ReplaySearchSessionTime( int sessionNum, int sessionTimeMS )
VideoCapture( IRacingSdkEnum.VideoCaptureMode videoCaptureMode )

Properties

public readonly IRacingSdkData Data

This is where you can find all of the data coming from the iRacing simulator. More on this in the IRacingSdkData Class chapter below.

public int UpdateInterval { get; set; } = 1 (default)

You can set UpdateInterval to any integer. Data frames are normally received from the iRacing simulator 60 times per second. A value of 1 or less will result in the OnTelemetryData event being fired for every data frame. Values above 1 means means you want to discard data frames to reduce how often the event is fired. For example, setting this to 2 means to fire the event every second data frame.

public bool IsStarted { get; private set; }

This property indicates whether or not this instance of IRSDKSharper is in the started state or is in the stopped state.

public bool IsConnected { get; private set; }

This property indicates whether or not the iRacing simulator is running and broadcasting data frames.

public event Action<Exception>? OnException

Exceptions caught within any of the three background tasks will be passed into OnException. You will likely want to copy the exception information somewhere and handle it from within your main thread. At this point, the background task that fired the exception will terminate. You can call Stop then Start (outside of your event handler) to clean up and restart IRSDKSharper.

public event Action? OnConnected

The OnConnected event is fired when IRSDKSharper has detected that the iRacing simulator has started up and is broadcasting telemetry data.

public event Action? OnDisconnected

The OnDisconnected event is fired when IRSDKSharper has detected that the iRacing simulator has exited. IRSDKSharper will start waiting for the iRacing simulator to come back and start broadcasting telemetry data again. If and when it does, the OnConnected event will be fired again at that time.

public event Action? OnSessionInfo

The OnSessionInfo event is fired after IRSDKSharper has received and fully processed the YAML session information data from the iRacing simulator. IRSDKSharper will not process any more frames of data until your event handler completes. For this reason, it is important that you do things quickly in your event handler in order to avoid dropping frames of data.

public event Action? OnTelemetryData

The OnTelemetryData event is fired whenever we receive a new frame of telemetry data from the iRacing simulator. IRSDKSharper will not process any more frames of data until your event handler completes. For this reason, it is important that you do things quickly in your event handler in order to avoid dropping frames of data.

IRacingSdkData Class

All iRacing simulator data can be accessed through the IRSDKSharper.Data property.

Properties

Data.SessionInfo

This is the session information data (the decoded YAML string).

Data.SessionInfoYaml

This is the raw un-decoded YAML string that we received from the iRacing simulator.

Data.TelemetryDataProperties

This is a dictionary describing each of the available iRacing simulator telemetry variables that is being broadcast. Each item in this dictionary has the following properties -

item.VarType
item.Offset
item.Count
item.Name
item.Desc
item.Unit

iRacing Simulator Data Header

You can access the various properties of the iRacing simulator data header if you need them.

Data.Version
Data.Status
Data.TickRate
Data.SessionInfoUpdate
Data.SessionInfoLength
Data.SessionInfoOffset
Data.VarCount
Data.VarHeaderOffset
Data.BufferCount
Data.BufferLength

Computed

There are also the following calculated properties available as well.

Data.TickCount
Data.Offset
Data.FramesDropped

The FramesDropped property is a useful one - you can check it to see if we are dropping telemetry data frames. Usually just a couple of frames are dropped at the beginning when the iRacing simulator starts up. Ideally there should be no frames dropped after that point.

Methods

To access the actual values of this telemetry data you would use one of the following methods³.

char GetChar( string name, int index = 0 )
bool GetBool( string name, int index = 0 )
int GetInt( string name, int index = 0 )
uint GetBitField( string name, int index = 0 )
float GetFloat( string name, int index = 0 )
double GetDouble( string name, int index = 0 )

You may also use this generic method as well, which would return the data value as a generic object -

object GetValue( string name, int index = 0 )

Useful tips

Test project

There is a test project that I have created that demonstrates the use of IRSDKSharper. This test project displays every telemetry and session information data in real time. The test project can be found over here: https://github.com/mherbold/IRSDKSharperTest

Differences to IRSDKSharp

1. The connection loop is never terminated in IRSDKSharp even though it is not needed any more after the iRacing simulator starts up.
2. IRSDKSharp handles both session information updates and telemetry data in the same background task. Since the processing of the YAML session information string can take several frames, this causes an undesired stutter or frame drops in the telemetry data. IRSDKSharper does not suffer from this issue.
3. The methods used to retrieve telemetry data runs many times faster in IRSDKSharper compared to IRSDKSharp, and in release builds they resolve to very fast inline direct memory access calls.
4. IRSDKSharper fixes known issues with the iRacing SDK (see below).

Fixes to IRSDK

Unfortunately, the iRacing SDK has some bugs and errors. Most of these bugs are known to the developers at iRacing, but they will not be fixed due to the likelihood of breaking compatibility with existing apps. IRSDKSharper fixes all of these known issues -

1. The CarsLeftRight telemetry data is incorrectly declared to be a bit field by the iRacing simulator. IRSDKSharper corrects this property to be an integer.
2. The PaceFlags telemetry data is incorrectly declared to be an integer by the iRacing simulator. IRSDKSharper corrects this property to be a bit field.
3. The iRacing simulator session information YAML data is improperly formatted and will crash deserializers under certain conditions. IRSDKSharper patches the YAML so it is properly formatted.

Roadmap

1. Add automatic recording / playback of telemetry data that is missing in iRacing's replay files.
2. Add useful additional telemetry derived from normalization / corrections to iRacing telemetry and session information data.