MJPEG Player in JavaScript

license.txt

Copyright 2015 Matthew Brush

Permission is hereby granted, free of charge, to any person obtaining a 
copy of this software and associated documentation files (the 
"Software"), to deal in the Software without restriction, including 
without limitation the rights to use, copy, modify, merge, publish, 
distribute, sublicense, and/or sell copies of the Software, and to 
permit persons to whom the Software is furnished to do so, subject to 
the following conditions:

The above copyright notice and this permission notice shall be included 
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

mjpeg.js

// namespace MJPEG { ...
var MJPEG = (function(module) {
  "use strict";

  // class Stream { ...
  module.Stream = function(args) {
    var self = this;
    var autoStart = args.autoStart || false;

    self.url = args.url;
    self.refreshRate = args.refreshRate || 500;
    self.onStart = args.onStart || null;
    self.onFrame = args.onFrame || null;
    self.onStop = args.onStop || null;
    self.callbacks = {};
    self.running = false;
    self.frameTimer = 0;

    self.img = new Image();
    if (autoStart) {
      self.img.onload = self.start;
    }
    self.img.src = self.url;

    function setRunning(running) {
      self.running = running;
      if (self.running) {
        self.img.src = self.url;
        self.frameTimer = setInterval(function() {
          if (self.onFrame) {
            self.onFrame(self.img);
          }
        }, self.refreshRate);
        if (self.onStart) {
          self.onStart();
        }
      } else {
        self.img.src = "#";
        clearInterval(self.frameTimer);
        if (self.onStop) {
          self.onStop();
        }
      }
    }

    self.start = function() { setRunning(true); }
    self.stop = function() { setRunning(false); }
  };

  // class Player { ...
  module.Player = function(canvas, url, options) {

    var self = this;
    if (typeof canvas === "string" || canvas instanceof String) {
      canvas = document.getElementById(canvas);
    }
    var context = canvas.getContext("2d");

    if (! options) {
      options = {};
    }
    options.url = url;
    options.onFrame = updateFrame;
    options.onStart = function() { console.log("started"); }
    options.onStop = function() { console.log("stopped"); }

    self.stream = new module.Stream(options);

    canvas.addEventListener("click", function() {
      if (self.stream.running) { self.stop(); }
      else { self.start(); }
    }, false);

    function scaleRect(srcSize, dstSize) {
      var ratio = Math.min(dstSize.width / srcSize.width,
                           dstSize.height / srcSize.height);
      var newRect = {
        x: 0, y: 0,
        width: srcSize.width * ratio,
        height: srcSize.height * ratio
      };
      newRect.x = (dstSize.width/2) - (newRect.width/2);
      newRect.y = (dstSize.height/2) - (newRect.height/2);
      return newRect;
    }

    function updateFrame(img) {
        var srcRect = {
          x: 0, y: 0,
          width: img.naturalWidth,
          height: img.naturalHeight
        };
        var dstRect = scaleRect(srcRect, {
          width: canvas.width,
          height: canvas.height
        });
      try {
        context.drawImage(img,
          srcRect.x,
          srcRect.y,
          srcRect.width,
          srcRect.height,
          dstRect.x,
          dstRect.y,
          dstRect.width,
          dstRect.height
        );
        console.log(".");
      } catch (e) {
        // if we can't draw, don't bother updating anymore
        self.stop();
        console.log("!");
        throw e;
      }
    }

    self.start = function() { self.stream.start(); }
    self.stop = function() { self.stream.stop(); }
  };

  return module;

})(MJPEG || {});

player.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8"/>
    <title>Player</title>
  </head>
  <body>
    <canvas id="player" style="background: #000;">
      Your browser sucks.
    </canvas>
  </body>
  <script src="mjpeg.js"></script>
  <script>
    var player = new MJPEG.Player("player", "http://localhost:8001");
    player.start();
  </script>
</html>

How can I add authentication information for the stream? my IP cam uses basic http authentication, and entering the url as http://user:pass@ip/ doesn't seem to work.

Thanks

thanks a lot ! 👍

I found this and also need basic authentication. How do I do that? thanks,

I'm don't know for sure, but a quick Google suggests you might need to use XMLHttpRequest to set the Authentication field in the request headers as discussed here, rather than just setting the image element's URL as shown in the Gist.

it is not working on IE or Edge, can you tell us the reason why??

It also is not working with mobile browsers. Because this shit is just fat emulation of tag.
You may not use this plugin, but use simple <img src='http://localhost:8001'> instead.

Direct embedding with img tag provides way less control. Here you can control the frame rate or even reuse the captured image that is valuable for advanced applications. This project is a valuable web resource.

This project is relying on a browser bug. UAs are asked to only render the first frame of any animated image inside an <img> tag, and this includes MJPEG streams.

@Kaaiido: Your source is only for canvas. But this JS uses an JS Image, and copies its Pictures Picture per Picture on the canvas. Btw, your sources says nothing about tags as well.

Sadly the browsers can't handle HD ready MJPEG streams without cooking on the CPU (while VLC can this flawlessly) - https://bugs.chromium.org/p/chromium/issues/detail?id=894753&can=2&start=0&num=100&q=&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified&groupby=&sort=

BTW this script doesn't really limit the transmitted frames, it's just limiting how many are shown per second.

I tested it with 4 cameras each at 1280x1024 and using this script they use 150mbit/s and if I just include them using the img tag the traffic is exactly the same

how to set play() and pause() at run time in between video at runtime.

This is already being done. If you click on the video, it will stop it. Click again to play it.