JavaScript Module - Pointer Detector Filter

This web application consists on a WebRTC video communication in mirror (loopback) with a pointer tracking filter element.

注解

This tutorial has been configurated for using https. Follow these instructions for securing your application.

For the impatient: running this example

First of all, you should install Kurento Media Server to run this demo. Please visit the installation guide for further information. In addition, the built-in module kms-pointerdetector-6.0 should be also installed:

sudo apt-get install kms-pointerdetector-6.0

Be sure to have installed Node.js and Bower in your system. In an Ubuntu machine, you can install both as follows:

curl -sL https://deb.nodesource.com/setup_4.x | sudo bash -
sudo apt-get install -y nodejs
sudo npm install -g bower

Due to Same-origin policy, this demo has to be served by an HTTP server. A very simple way of doing this is by means of an HTTP Node.js server which can be installed using npm :

sudo npm install http-server -g

You also need the source code of this demo. You can clone it from GitHub. Then start the HTTP server:

git clone https://github.com/Kurento/kurento-tutorial-js.git
cd kurento-tutorial-js/kurento-pointerdetector
git checkout 6.6.1
bower install
http-server -p 8443 -S -C keys/server.crt -K keys/server.key

Finally, access the application connecting to the URL https://localhost:8443/ through a WebRTC capable browser (Chrome, Firefox).

注解

These instructions work only if Kurento Media Server is up and running in the same machine as the tutorial. Kurento Media Server must use WebSockets over SSL/TLS (WSS), so make sure you check this too. It is possible to locate the KMS in other machine simple adding the parameter ws_uri to the URL:

https://localhost:8443/index.html?ws_uri=wss://kms_host:kms_port/kurento

Notice that the Kurento Media Server must connected using a Secure WebSocket (i.e., the KMS URI starts with wss://). For this reason, the support for secure WebSocket must be enabled in the Kurento Media Server you are using to run this tutorial. For further information about securing applications, please visit the following page.

Understanding this example

This application uses computer vision and augmented reality techniques to detect a pointer in a WebRTC stream based on color tracking.

The interface of the application (an HTML web page) is composed by two HTML5 video tags: one for the video camera stream (the local client-side stream) and other for the mirror (the remote stream). The video camera stream is sent to Kurento Media Server, which processes and sends it back to the client as a remote stream. To implement this, we need to create a Media Pipeline composed by the following Media Element s:

WebRTC with PointerDetector filter in loopback Media Pipeline

WebRTC with PointerDetector filter in loopback Media Pipeline

The complete source code of this demo can be found in GitHub.

This example is a modified version of the Magic Mirror tutorial. In this case, this demo uses a PointerDetector instead of FaceOverlay filter.

In order to perform pointer detection, there must be a calibration stage, in which the color of the pointer is registered by the filter. To accomplish this step, the pointer should be placed in a square in the upper left corner of the video, as follows:

Pointer calibration stage

Pointer calibration stage

注解

Modules can have options. For configuring these options, you’ll need to get the constructor for them. In Javascript and Node, you have to use kurentoClient.getComplexType(‘qualifiedName’) . There is an example in the code.

In that precise moment, a calibration operation should be carried out. This is done by clicking on the Calibrate blue button of the GUI.

After that, the color of the pointer is tracked in real time by Kurento Media Server. PointerDetectorFilter can also define regions in the screen called windows in which some actions are performed when the pointer is detected when the pointer enters (WindowIn event) and exits (WindowOut event) the windows. This is implemented in the JavaScript logic as follows:

...
kurentoClient.register('kurento-module-pointerdetector')
const PointerDetectorWindowMediaParam = kurentoClient.getComplexType('pointerdetector.PointerDetectorWindowMediaParam')
const WindowParam                     = kurentoClient.getComplexType('pointerdetector.WindowParam')
...

kurentoClient(args.ws_uri, function(error, client) {
  if (error) return onError(error);

  client.create('MediaPipeline', function(error, _pipeline) {
    if (error) return onError(error);

    pipeline = _pipeline;

    console.log("Got MediaPipeline");

    pipeline.create('WebRtcEndpoint', function(error, webRtc) {
      if (error) return onError(error);

      console.log("Got WebRtcEndpoint");

      setIceCandidateCallbacks(webRtcPeer, webRtc, onError)

      webRtc.processOffer(sdpOffer, function(error, sdpAnswer) {
        if (error) return onError(error);

        console.log("SDP answer obtained. Processing ...");

        webRtc.gatherCandidates(onError);
        webRtcPeer.processAnswer(sdpAnswer);
      });

      var options =
      {
        calibrationRegion: WindowParam({
          topRightCornerX: 5,
          topRightCornerY:5,
          width:30,
          height: 30
        })
      };

      pipeline.create('pointerdetector.PointerDetectorFilter', options, function(error, _filter) {
        if (error) return onError(error);

        filter = _filter;

        var options = PointerDetectorWindowMediaParam({
          id: 'window0',
          height: 50,
          width:50,
          upperRightX: 500,
          upperRightY: 150
        });

        filter.addWindow(options, onError);

        var options = PointerDetectorWindowMediaParam({
          id: 'window1',
          height: 50,
          width:50,
          upperRightX: 500,
          upperRightY: 250
        });

        filter.addWindow(options, onError);

        filter.on ('WindowIn', function (data){
          console.log ("Event window in detected in window " + data.windowId);
        });

        filter.on ('WindowOut', function (data){
          console.log ("Event window out detected in window " + data.windowId);
        });

        console.log("Connecting ...");
        client.connect(webRtc, filter, webRtc, function(error) {
          if (error) return onError(error);

          console.log("WebRtcEndpoint --> Filter --> WebRtcEndpoint");
        });
      });
    });
  });
});

The following picture illustrates the pointer tracking in one of the defined windows:

Pointer tracking over a window

Pointer tracking over a window

In order to carry out the calibration process, this JavaScript function is used:

function calibrate() {
  if(filter) filter.trackColorFromCalibrationRegion(onError);
}

function onError(error) {
  if(error) console.error(error);
}

注解

The TURN and STUN servers to be used can be configured simple adding the parameter ice_servers to the application URL, as follows:

https://localhost:8443/index.html?ice_servers=[{"urls":"stun:stun1.example.net"},{"urls":"stun:stun2.example.net"}]
https://localhost:8443/index.html?ice_servers=[{"urls":"turn:turn.example.org","username":"user","credential":"myPassword"}]

Dependencies

The dependencies of this demo has to be obtained using Bower. The definition of these dependencies are defined in the bower.json file, as follows:

"dependencies": {
   "kurento-client": "6.6.0",
   "kurento-utils": "6.6.2"
   "kurento-module-pointerdetector": "6.6.0"
}

To get these dependencies, just run the following shell command:

bower install

注解

We are in active development. You can find the latest versions at Bower.