IVideoCompositor Interface

Definition

Namespace:

Windows.Media.Effects

The interface you implement to create a custom video compositor.

public interface class IVideoCompositor : IMediaExtension

/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
/// [Windows.Foundation.Metadata.Guid(2232464446, 16908, 16911, 150, 199, 124, 152, 187, 161, 252, 85)]
struct IVideoCompositor : IMediaExtension

[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
[Windows.Foundation.Metadata.Guid(2232464446, 16908, 16911, 150, 199, 124, 152, 187, 161, 252, 85)]
public interface IVideoCompositor : IMediaExtension

Public Interface IVideoCompositor
Implements IMediaExtension

Attributes

ContractVersionAttribute GuidAttribute

Implements

IMediaExtension

Windows requirements

Device family	Windows 10 (introduced in 10.0.10240.0)
API contract	Windows.Foundation.UniversalApiContract (introduced in v1.0)

Examples

using Microsoft.Graphics.Canvas; using Microsoft.Graphics.Canvas.Effects; using Windows.Foundation.Collections; using Windows.Graphics.DirectX.Direct3D11; using Windows.Media.Effects; using Windows.Media.MediaProperties; using Windows.UI;

namespace Effects
{
    /// <summary>
    /// Chroma key compositor
    /// <list type="Bullet">
    /// <listheader>Properties</listheader>
    /// <item>Color (Color) : Chroma key color (default is black)</item>
    /// <item>Feather (Boolean): true to soften edges of the output (default is false)</item>
    /// <item>Tolerance (float): Color tolerance 0-1 (default is 0.1)</item>
    /// <item>InvertAlpha (Boolean): invert the alpha value (default is false)</item>
    /// </list>
    /// </summary>
    public sealed class ChromaKeyVideoCompositor : IVideoCompositor
    {
        #region Fields
        private VideoEncodingProperties _backgroundProperties;
        private CanvasDevice _canvasDevice;
        #endregion

        #region Properties
        /// <summary>
        /// Gets the chroma-key color
        /// </summary>
        public Color Color { get; private set; } = Colors.Black;

        /// <summary>
        /// Gets a value indicating whether to feather the edges of the chroma key
        /// </summary>
        public bool Feather { get; private set; } = false;

        /// <summary>
        /// Gets the color tolerance 
        /// </summary>
        public float Tolerance { get; private set; } = 0.1f;

        /// <summary>
        /// Gets a value indicating whether to invert the alpha transparency
        /// </summary>
        public bool InvertAlpha { get; private set; } = false;

        /// <summary>
        /// Gets a value indicating whether the compositor is time-independent
        /// </summary>
        public bool TimeIndependent => true;
        #endregion

        #region Methods
        /// <summary>
        /// Sets the encoding properties
        /// </summary>
        /// <param name="backgroundProperties">the background properties</param>
        /// <param name="device">the Direct3D device</param>
        public void SetEncodingProperties(VideoEncodingProperties backgroundProperties, IDirect3DDevice device)
        {
            _backgroundProperties = backgroundProperties;

            _canvasDevice = CanvasDevice.CreateFromDirect3D11Device(device);
        }

        /// <summary>
        /// Composite the frame
        /// </summary>
        /// <param name="context">the composite frame context</param>
        public void CompositeFrame(CompositeVideoFrameContext context)
        {
            foreach (var surface in context.SurfacesToOverlay)
            {
                using (CanvasBitmap inputBitmap = CanvasBitmap.CreateFromDirect3D11Surface(_canvasDevice, surface))
                using (CanvasRenderTarget renderTarget = CanvasRenderTarget.CreateFromDirect3D11Surface(_canvasDevice, context.OutputFrame.Direct3DSurface))
                using (CanvasDrawingSession ds = renderTarget.CreateDrawingSession())
                using (var chromaKeyEffect = new ChromaKeyEffect
                {
                    Source = inputBitmap,
                    Color = Color,
                    Feather = Feather,
                    Tolerance = Tolerance,
                    InvertAlpha = InvertAlpha
                })
                {
                    var overlay = context.GetOverlayForSurface(surface);

                    var destinationRectangle = overlay.Position;

                    var sourceRectangle = inputBitmap.Bounds;

                    var opacity = System.Convert.ToSingle(overlay.Opacity);

                    ds.DrawImage(chromaKeyEffect, destinationRectangle, sourceRectangle, opacity);
                }
            }
        }

        /// <summary>
        /// Close the compositor & dispose of the canvas device
        /// </summary>
        /// <param name="reason">the media effect closed reason</param>
        public void Close(MediaEffectClosedReason reason)
        {
            if (_canvasDevice != null)
            {
                _canvasDevice.Dispose();
                _canvasDevice = null;
            }
        }

        /// <summary>
        /// Discard of the queued frames
        /// </summary>
        /// <remarks>this does nothing</remarks>
        public void DiscardQueuedFrames()
        {
        }

        /// <summary>
        /// Sets the properties passed into the compositor
        /// </summary>
        /// <param name="configuration">the configuration</param>
        public void SetProperties(IPropertySet configuration)
        {
            if (configuration == null)
            {
                return;
            }

            object value;

            if (configuration.TryGetValue("Color", out value))
            {
                Color = (Color)value;
            }

            if (configuration.TryGetValue("Tolerance", out value))
            {
                Tolerance = (float)value;
            }

            if (configuration.TryGetValue("Feather", out value))
            {
                Feather = (bool)value;
            }

            if (configuration.TryGetValue("InvertAlpha", out value))
            {
                InvertAlpha = (bool)value;
            }
        }
        #endregion
    }
}

Remarks

1. In a Windows Runtime Component project, derive a public sealed class from this interface (see example below).

2. Use the full class name in a MediaOverlayLayer constructor.

   var propertySet = new PropertySet { ["Feather"] = true, ["Tolerance"] = 0.2f, ["Color"] = Colors.Blue };

   var compositorDefinition = new VideoCompositorDefinition( "Effects.ChromaKeyVideoCompositor", propertySet);

   var mediaOverlayLayer = new MediaOverlayLayer(compositorDefinition);

Properties

TimeIndependent

Gets a value that indicates whether the custom video effect is time independent.

Methods

Close(MediaEffectClosedReason)	Called when the video compositor should close and clean up allocated resources.
CompositeFrame(CompositeVideoFrameContext)	Called when frames are available for composition by a custom video compositor.
DiscardQueuedFrames()	Called to allow video compositor implementations optionally discard any stored state related to frames that have already been received.
SetEncodingProperties(VideoEncodingProperties, IDirect3DDevice)	Called to set the encoding properties of a custom video compositor.
SetProperties(IPropertySet)	Sets the configuration properties that were supplied when the media parser or codec was registered. (Inherited from IMediaExtension)

See also

• IMediaExtension