Why does using VideoTransformEffectDefinition affect the camera brightness

I don't want to use SetPreviewRotation because I also need to use VideoTransformEffectDefinition‘s mirror and crop.

Hello @LXY ,

Welcome to Microsoft Q&A!

How do you add VideoTransformEffectDefinition to MediaCapture? Could you please provide a minimal-reproducible-example to help us further check the problem for you?

Thank you.

MainPage.xaml

<Page
    x:Class="App1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App1"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <StackPanel Loaded="StackPanel_Loaded" Orientation="Horizontal">
        <StackPanel>
            <Button Content="AddEffect" x:Name="AddEffectButton"           Click="AddEffectButton_Click"/>
            <Button Content="ClearEffects" x:Name="ClearEffectsButton" Click="ClearEffectsButton_Click"/>
            <TextBlock x:Name="StateBlock"/>
        </StackPanel>
        <CaptureElement x:Name="CameraElement" Width="600" Height="400"/>
    </StackPanel>
</Page>

MainPage.xaml.cs

MediaCapture mediaCapture;
Windows.Media.Effects.VideoTransformEffectDefinition VideoEffect;
private async void StackPanel_Loaded(object sender, RoutedEventArgs e) {
      VideoEffect = new Windows.Media.Effects.VideoTransformEffectDefinition();
      mediaCapture = new MediaCapture();
      await mediaCapture.InitializeAsync();
      CameraElement.Source = mediaCapture;
      await mediaCapture.StartPreviewAsync();
 }
private void AddEffectButton_Click(object sender, RoutedEventArgs e) {
	  VideoEffect.Rotation= Windows.Media.MediaProperties.MediaRotation.None;
      _ = mediaCapture.AddVideoEffectAsync(VideoEffect, MediaStreamType.VideoPreview);
      StateBlock.Text += "AddEffect" + Environment.NewLine;
}
private void ClearEffectsButton_Click(object sender, RoutedEventArgs e) {
       _=mediaCapture.ClearEffectsAsync(MediaStreamType.VideoPreview);
       StateBlock.Text += "ClearEffects" + Environment.NewLine;
}

Practical results：

Hello @LXY ,

I tested your code on Surface, the camera brightness did not change.

Can this behavior be reproduced on other devices or other cameras?

Thank you.