Question

我正在开发一个用于检测网络摄像头帧内运动的应用程序。为此，我使用IBasicVideoEffect从MediaCapture逐个提取帧。我创建了继承CustomEffect的类IBasicVideoEffect。我使用OpenCV进行运动检测，它工作正常。它也给我运动检测水平。如果运动级别大于阈值，我想从CustomEffect引发事件。

但是对于videoDefination代码是：

var videoDefinition = new VideoEffectDefinition(typeof(CustomEffect).ToString());

这里针对videoDefinition构造函数，它要求ClassID，如何从CustomEffect对象获取事件。我想从CustomEffect（例如：MotionDetectedEvent）

提出自定义事件

这是我的CustomEffect类：

public sealed class CustomEffect : IBasicVideoEffect
{
    private OpenCVHelper _helper;

    private IPropertySet _configuration;

    internal event EventHandler<EventArgs> MotionDetected;
    public void SetProperties(IPropertySet configuration)
    {
        _configuration = configuration;
    }

    public void SetEncodingProperties(VideoEncodingProperties encodingProperties,
        IDirect3DDevice device)
    {
    }

    private bool IsToDetectMotion
    {
        get
        {
            object val;
            if (_configuration != null &&
                _configuration.TryGetValue("IsToDetectMotion", out val))
                return (bool) val;
            return false;
        }
    }

    public void ProcessFrame(ProcessVideoFrameContext context)
    {
        var tempBitmap = context.OutputFrame.SoftwareBitmap;


        context.InputFrame.SoftwareBitmap.CopyTo(tempBitmap);
        var originalBitmap = SoftwareBitmap.Convert(tempBitmap, BitmapPixelFormat.Bgra8,
            BitmapAlphaMode.Straight);

        var outputBitmap = new SoftwareBitmap(BitmapPixelFormat.Bgra8,
            originalBitmap.PixelWidth, originalBitmap.PixelHeight,
            BitmapAlphaMode.Straight);


        if (!IsToDetectMotion)
        {
            context.InputFrame.SoftwareBitmap.CopyTo(context.OutputFrame.SoftwareBitmap);
            return;
        }

        if (_helper == null)
            _helper = new OpenCVHelper();

        var level = _helper.MotionDetector(tempBitmap, outputBitmap);

        RaiseMotionDetectedEvent();

        Debug.WriteLine(level.ToString());

        outputBitmap.CopyTo(context.OutputFrame.SoftwareBitmap);
    }
    private void RaiseMotionDetectedEvent()
    {
        if (MotionDetected != null)
            MotionDetected(this, new EventArgs());
    }


    public void Close(MediaEffectClosedReason reason)
    {
    }

    public void DiscardQueuedFrames()
    {
    }

    public bool IsReadOnly { get; }

    public IReadOnlyList<VideoEncodingProperties> SupportedEncodingProperties
    {
        get
        {
            var encodingProperties = new VideoEncodingProperties();
            encodingProperties.Subtype = "ARGB32";
            return new List<VideoEncodingProperties> {encodingProperties};

            // If the list is empty, the encoding type will be ARGB32.
            // return new List<VideoEncodingProperties>();
        }
    }

    public MediaMemoryTypes SupportedMemoryTypes { get; }
    public bool TimeIndependent { get; }
}

Answer 1

//in Windows Runtime Component

public sealed class FrameArgs
    {
        public FrameArgs(int frameCount)
        {
            FrameCount = frameCount;
        }

        public int FrameCount 
        { get; }
    }

public sealed partial class CustomEffect
    {
        #region ProcessFrameCompleted

        public EventHandler<Object> ProcessFrameCompleted
        {
            get
            {
                object val;
                if (configuration != null && configuration.TryGetValue(nameof(ProcessFrameCompleted), out val))
                {
                    return (EventHandler<Object>)val;
                }

                return null;
            }
        }

        public void RaiseProcessFrameCompleted(FrameArgs args)
        {
            ProcessFrameCompleted?.Invoke(null, (Object)args);
        }

        #endregion

        //call as necessary
        //RaiseProcessFrameCompleted(new FrameArgs(frameCount));
    }




//in your app
public static async Task<IMediaExtension> AddCustomEffect(MediaCapture mediaCapture, EventHandler<FrameArgs> callBack)
        {
            if (mediaCapture == null)
            {
                throw new ArgumentException("Parameter cannot be null", nameof(mediaCapture));
            }

            var videoEffectDefinition = 
                // ReSharper disable once AssignNullToNotNullAttribute
                new VideoEffectDefinition(typeof(CustomEffect).FullName);

            var videoEffect =
                await mediaCapture.AddVideoEffectAsync(videoEffectDefinition, MediaStreamType.VideoPreview);

            videoEffect.SetProperties(
                new PropertySet() 
                { 
                    { 
                        "ProcessFrameCompleted", 
                        new EventHandler<object>((sender, e) =>
                        {
                            var args = (FrameArgs)e;
                            int frameCount = args.FrameCount;

                            callBack?.Invoke(sender, args);
                        })
                    }
                });

            return videoEffect;
        }

UWP自定义视频效果

1 个答案: