Nodejs realizes mature live broadcast

With the development of the Internet, live broadcast has become a very popular form and has a wide range of applications in entertainment, education and business fields. For developers, how to implement a mature live broadcast system is an important consideration. This article will introduce how to use nodejs to implement a mature live broadcast system.

1. Basic functions of the live broadcast system

Before understanding how to use nodejs to implement live broadcast, it is necessary to understand some basic functions of the live broadcast system.

1. Video collection: In the live broadcast system, video collection is the starting point of the live broadcast. Video capture is to capture the images captured by the camera.
2. Video encoding: Video encoding is to compress and encode the collected original video data and package it into a video stream with a smaller capacity for transmission during network transmission.
3. Video push: Video push is to push the encoded video data to the server through the network.
4. Video server: The video server is a server that processes, decodes and converts the pushed video data.
5. Video player: The live broadcast system needs a video player so that users can watch the live broadcast through the video player.

The above are the essential basic functions in the live broadcast system. The following will introduce how to use nodejs to implement these functions.

2. Use nodejs to implement video collection

nodejs provides many third-party libraries for video collection, such as node-opencv, node-gd and node-canvas. We can use different libraries to complete the video collection function according to actual needs. Taking node-opencv as an example, you first need to install opencv through npm.

The command to install opencv is as follows:

npm install opencv

After installing opencv, we should write the corresponding code to collect the video. The following code shows how to use node-opencv to implement video collection

var cv = require('opencv');

var camera = new cv.VideoCapture(0);

setInterval(function() {
  camera.read(function(err, im) {
    if (err) throw err;
    console.log(im.size());
    if (im.size()[0] > 0 && im.size()[1] > 0)
      im.detectObject(cv.FACE_CASCADE, {}, function(err, faces) {
        if (err) throw err;
        for (var i = 0; i < faces.length; i++) {
          var face = faces[i];
          im.rectangle([face.x, face.y], [face.width, face.height], [0, 255, 0], 2);
        }
        im.save('./tmp/' + Date.now() + '.jpg');
      });
  });
}, 20);

This code will read the video from the local camera, detect the face in it, and save the face frame into the image.

3. Use nodejs to implement video encoding and streaming

There are many third-party libraries in nodejs that can be used to implement video encoding and streaming functions, such as FFmpeg, node-media-server and node-rtsp-stream etc. Here we take node-rtsp-stream as an example, which is a node.js stream real-time conversion library that uses FFmpeg. Live streams can be quickly converted between RTSP or MP4.

The command to install node-rtsp-stream is as follows:

npm install node-rtsp-stream

The following code shows how to use node-rtsp-stream to implement video encoding And push streaming

var stream = require('node-rtsp-stream');

var options = { 
  name: 'streamName',
  url: 'rtsp://192.168.1.142:554/av0_1',
  port: 9999
}

stream.createServer(options);

In the above code, we set the streamName to "streamName", the url is the collected video address, and the port is the stream output port number.

4. Use nodejs to implement the video server

Using nodejs to implement the video server is more complicated and requires the use of a variety of third-party libraries. In the video server, we need to complete a series of operations such as video decoding, transcoding, storage and distribution. It is recommended to use WebRTC here. WebRTC is an open source project that can be used on browsers and mobile platforms, covering various components of real-time communications (RTC), including voice, video and data communications. WebRTC's P2P technology makes video communication easier while ensuring communication efficiency. Video decoding, transcoding, storage and distribution functions can be easily implemented using WebRTC.

5. Use nodejs to implement the video player

We can use HLS (HTTP Live Streaming) to implement the video player. HLS is a streaming media protocol based on HTTP. HLS splits a long stream into short segments (TS format). The client can play the entire stream by repeatedly requesting these short segments.

We can use hls.js to implement the client-side HLS player. hls.js is an HLS client written in JavaScript that supports a variety of web browsers and platforms, including mobile devices. You can easily implement a video player on the page using hls.js.

6. Summary

This article introduces the implementation of a mature live broadcast system through nodejs. We can use the third-party library of nodejs to complete functions such as video collection, encoding and streaming. At the same time, we also introduced how to use WebRTC and how to use HLS to implement a video player. In this process, we saw the power and convenience of nodejs. I believe this article will be helpful to both beginners and developers with a certain nodejs foundation.

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