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How to Deal with Slow WebCam Preview on Start

Environment

Product Version 2021.3.1123
Product RadWebCam for WinForms

Problem

Camera preview is very slow on its first start-up. When you click on the snapshot icon and afterwards the button with the cross to retake another snapshot, the camera preview is smooth.

Solution

One possible approach is to force taking a snapshot at least once and then reject the preview image. This can be achieved using the following code snippet:


private ReadOnlyCollection<MediaFoundationDeviceInfo> videoDevices;
private ReadOnlyCollection<MediaFoundationVideoFormatInfo> videoFormats;
private ReadOnlyCollection<MediaFoundationDeviceInfo> audioDevices; 

Timer t = new Timer();
public CameraView()
{
    InitializeComponent();
    videoDevices = RadWebCam.GetVideoCaptureDevices();
    videoFormats = RadWebCam.GetVideoFormats(videoDevices[0], true);
    audioDevices = RadWebCam.GetAudioCaptureDevices(); 
} 
private void CameraView_Load(object sender, EventArgs e)
{
    radWebCam1.Initialized += RadWebCam1_Initialized;
    radWebCam1.Initialize(videoDevices[0], videoFormats[0], audioDevices[0]);
    radWebCam1.Start(); 
}

private void RadWebCam1_Initialized(object sender, EventArgs e)
{
    t.Interval = 200;
    t.Tick += T_Tick;
    t.Start();
}

private void T_Tick(object sender, EventArgs e)
{
    t.Stop();
    radWebCam1.TakeSnapshot();
    radWebCam1.DiscardSnapshot();
}



Private videoDevices As ReadOnlyCollection(Of MediaFoundationDeviceInfo)
Private videoFormats As ReadOnlyCollection(Of MediaFoundationVideoFormatInfo)
Private audioDevices As ReadOnlyCollection(Of MediaFoundationDeviceInfo)
Private t As Timer = New Timer()

Public Sub New()
    InitializeComponent()
    videoDevices = RadWebCam.GetVideoCaptureDevices()
    videoFormats = RadWebCam.GetVideoFormats(videoDevices(0), True)
    audioDevices = RadWebCam.GetAudioCaptureDevices()
End Sub

Private Sub CameraView_Load(ByVal sender As Object, ByVal e As EventArgs)
    AddHandler RadWebCam1.Initialized, AddressOf RadWebCam1_Initialized
    RadWebCam1.Initialize(videoDevices(0), videoFormats(0), audioDevices(0))
    RadWebCam1.Start()
End Sub

Private Sub RadWebCam1_Initialized(ByVal sender As Object, ByVal e As EventArgs)
    t.Interval = 200
    AddHandler t.Tick, AddressOf T_Tick
    t.Start()
End Sub

Private Sub T_Tick(ByVal sender As Object, ByVal e As EventArgs)
    t.[Stop]()
    RadWebCam1.TakeSnapshot()
    RadWebCam1.DiscardSnapshot()
End Sub


An alternative solution if the audio is not important for the precise scenario, feel free to pass null parameter to it:


radWebCam1.Initialize(videoDevices[0], videoFormats[0], null);



RadWebCam1.Initialize(videoDevices(0), videoFormats(0), Nothing)

See Also

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