# Special blocks

# Introduction

Special blocks are blocks that do not fit into any other category.

# Null Renderer

The null renderer block sends the data to null. This block may be required if your block has outputs you do not want to use.

# Block info

Name: NullRendererBlock.

Pin direction	Media type	Pins count
Input	Any	1

# The sample pipeline

The sample pipeline is shown below. It reads a file and sends the video data to the video samples grabber, where you can grab each video frame after decoding. The Null renderer block is used to end the pipeline.

graph LR;
    UniversalSourceBlock-->VideoSampleGrabberBlock;
    VideoSampleGrabberBlock-->NullRendererBlock;

# Sample code

private void Start()
{
  // create the pipeline
  var pipeline = new MediaBlocksPipeline();

  // create universal source block
  var filename = "test.mp4";
  var fileSource = new UniversalSourceBlock(await UniversalSourceSettings.CreateAsync(new Uri(filename)));

  // create video sample grabber block and add the event handler
  var sampleGrabber = new VideoSampleGrabberBlock();
  sampleGrabber.OnVideoFrameBuffer += sampleGrabber_OnVideoFrameBuffer;

  // create null renderer block
  var nullRenderer = new NullRendererBlock();

  // connect blocks
  pipeline.Connect(fileSource.VideoOutput, sampleGrabber.Input);        
  pipeline.Connect(sampleGrabber.Output, nullRenderer.Input);   

  // start the pipeline
  await pipeline.StartAsync();
}

private void sampleGrabber_OnVideoFrameBuffer(object sender, VideoFrameXBufferEventArgs e)
{
    // received new video frame
}

# Platforms

Windows, macOS, Linux, iOS, Android.

# Tee

The tee block splits the video or audio data stream into multiple streams that completely copy the original stream.

# Block info

Name: TeeBlock.

Pin direction	Media type	Pins count
Input	Any	1
Output	Same as input	2 or more

# The sample pipeline

graph LR;
    UniversalSourceBlock-->TeeBlock;
    TeeBlock-->VideoRendererBlock;
    TeeBlock-->H264EncoderBlock;
    H264EncoderBlock-->MP4SinkBlock;

# Sample code

var pipeline = new MediaBlocksPipeline();

var filename = "test.mp4";
var fileSource = new UniversalSourceBlock(await UniversalSourceSettings.CreateAsync(new Uri(filename)));

var videoTee = new TeeBlock(2);
var h264Encoder = new H264EncoderBlock(new OpenH264EncoderSettings());
var mp4Muxer = new MP4SinkBlock(new MP4SinkSettings(@"output.mp4"));
var videoRenderer = new VideoRendererBlock(pipeline, VideoView1);

pipeline.Connect(fileSource.VideoOutput, videoTee.Input);
pipeline.Connect(videoTee.Outputs[0], videoRenderer.Input);
pipeline.Connect(videoTee.Outputs[1], h264Encoder.Input);
pipeline.Connect(h264Encoder.Output, mp4Muxer.CreateNewInput(MediaBlockPadMediaType.Video));

await pipeline.StartAsync();

# Sample applications

Simple Capture Demo

# Platforms

Windows, macOS, Linux, iOS, Android.

# Super MediaBlock

The Super MediaBlock allows you to combine multiple blocks into a single block.

# Block info

Name: SuperMediaBlock.

Pin direction	Media type	Pins count
Input	Any	1
Output	Any	1

# The sample pipeline

graph LR;
    VirtualVideoSourceBlock-->SuperMediaBlock;
    SuperMediaBlock-->NullRendererBlock;

Inside the SuperMediaBlock:

graph LR;
    FishEyeBlock-->ColorEffectsBlock;

Final pipeline:

graph LR;
    VirtualVideoSourceBlock-->FishEyeBlock;
    subgraph SuperMediaBlock
    FishEyeBlock-->ColorEffectsBlock;
    end
    ColorEffectsBlock-->NullRendererBlock;

# Sample code

var pipeline = new MediaBlocksPipeline();

var videoViewBlock = new VideoRendererBlock(pipeline, VideoView1);

var videoSource = new VirtualVideoSourceBlock(new VirtualVideoSourceSettings());

var colorEffectsBlock = new ColorEffectsBlock(VisioForge.Core.Types.X.VideoEffects.ColorEffectsPreset.Sepia);
var fishEyeBlock = new FishEyeBlock();

var superBlock = new SuperMediaBlock();
superBlock.Blocks.Add(fishEyeBlock);
superBlock.Blocks.Add(colorEffectsBlock);
superBlock.Configure(pipeline);

pipeline.Connect(videoSource.Output, superBlock.Input);
pipeline.Connect(superBlock.Output, videoViewBlock.Input);

await pipeline.StartAsync();

# Platforms

Windows, macOS, Linux, iOS, Android.