[英]How to do video recording with Text overlay using Directshow and C#?
根据我以前的帖子,我尝试使用sampleGrabber来从视频文件中获取帧,然后调用回调函数:
Type comType = Type.GetTypeFromCLSID(new Guid("e436ebb3-524f-11ce-9f53-0020af0ba770"));
IGraphBuilder graphBuilder = (IGraphBuilder)Activator.CreateInstance(comType);
comType = Type.GetTypeFromCLSID(new Guid("C1F400A0-3F08-11d3-9F0B-006008039E37"));
ISampleGrabber sampleGrabber = (ISampleGrabber)Activator.CreateInstance(comType);
graphBuilder.AddFilter((IBaseFilter)sampleGrabber, "samplegrabber");
AMMediaType mediaType = new AMMediaType();
mediaType.majorType = MediaType.Video;
mediaType.subType = MediaSubType.RGB24;
mediaType.formatType = FormatType.VideoInfo;
sampleGrabber.SetMediaType(mediaType);
int hr = graphBuilder.RenderFile(@"D:\test.wmv", null);
IMediaEventEx mediaEvent = (IMediaEventEx)graphBuilder;
IMediaControl mediaControl = (IMediaControl)graphBuilder;
IVideoWindow videoWindow = (IVideoWindow)graphBuilder;
IBasicAudio basicAudio = (IBasicAudio)graphBuilder;
videoWindow.put_AutoShow(OABool.False);
basicAudio.put_Volume(-10000);
sampleGrabber.SetOneShot(false);
sampleGrabber.SetBufferSamples(true);
//the same object has implemented the ISampleGrabberCB interface.
//0 sets the callback to the ISampleGrabberCB::SampleCB() method.
sampleGrabber.SetCallback(this, 0);
mediaControl.Run();
EventCode eventCode;
mediaEvent.WaitForCompletion(-1, out eventCode);
Marshal.ReleaseComObject(sampleGrabber);
Marshal.ReleaseComObject(graphBuilder);
回叫功能
public int SampleCB ( double sampleTime, IMediaSample mediaSample )
{
//WHAT TO DO HERE.
}
我该如何在回叫功能中在每帧上添加叠加层,然后整个视频将与叠加层文本一起存储?
录制视频时,是否可以添加叠加文字?
在录制过程中添加文本覆盖的最佳方法是实现DMO或DirectShow Transform-Filter 。 我更喜欢DMO,因为它更简单,您以后可以在MediaFoundation中重用它。
您将RGB24或RGB32设置为DMO /滤镜的输入类型,然后可以使用GDI在每个帧上绘制所需的内容。
在Graph中看起来是这样的: VideoSource -> DMO -> ASF Writer
。
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