Virtual live broadcast

When users are shooting a video, the virtual live broadcast function is realized by image matting and later applying the virtual scene package (.capturescene) of Meishe SDk to the video.
The specific steps are as follows:

1. Initialize the StreamingContext. There are two ways to create a NvsStreamingContext singleton object. Here we choose to create singleton object without the flags.

   m_streamingContext = [NvsStreamingContext sharedInstance];

2. Set the callback and connects the capture preview output to the NvsLiveWindow control.

   //Sets the callback interface to the streaming context. m_streamingContext.delegate = self; m_streamingContext.assetPackageManager.delegate = self;

   //Connects capture preview output to the NvsLiveWindow control. [m_streamingContext connectCapturePreviewWithLiveWindow:self.liveWindow];

3. Add image matting capture Fx.

   NvsCaptureVideoFx *keyerFx = [m_streamingContext appendBuiltinCaptureVideoFx:"Master Keyer"]; if (keyerFx) { //Opens the overflow color removal. [keyerFx setBooleanVal:"Spill Removal" val:YES]; //Set the intensity of the overflow removal to the lowest. [keyerFx setFloatVal:"Spill Removal Intensity" val:0]; //Set the boundary shrinking strength. [keyerFx setFloatVal:"Shrink Intensity" val:0.4]; }

4. Start the capture preview.

   //Color pick is needed on the captured video. So Users need to use NvsStreamingEngineCaptureFlag_GrabCapturedVideoFrame flag. [m_streamingContext startCapturePreview:deviceIndex videoResGrade:NvsVideoCaptureResolutionGradeHigh flags:NvsStreamingEngineCaptureFlag_GrabCapturedVideoFrame aspectRatio:nil];

5. Click to pick color and pass the extracted background image color value to the key effect.

   NvsColor sampledColor = [m_streamingContext sampleColorFromCapturedVideoFrame:sampleRect];
   //Passes the extracted background image color value to the key effect. NvsCaptureVideoFx *keyerFx = [m_streamingContext getCaptureVideoFxByIndex:0]; if(keyerFx) [keyerFx setColorVal:"Key Color" val:&sampledColor];

6. Use the virtual scene package, and the virtual live scene will appear.

   [m_streamingContext applyCaptureScene:sceneId];