IVideoCompositor Interface

Definition

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

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

Methods

Applies to

See also

• IMediaExtension