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MJPEG Player in JavaScript
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.
// 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 || {});
<!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>
@gentilmente
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HI, it doesn't work for me, what could it be?
I use gphoto2 with a DSLR camera
with this command I can get a file: gphoto2 --capture-movie --stdout > liveview.mjpeg
or a live stream with: gphoto2 --capture-movie --stdout | ffmpeg -re -i pipe:0 -listen 1 -f mjpeg http://localhost:8080/feed.mjpg

and obvious change this line to: var player = new MJPEG.Player('player', './liveview.mjpeg'); in first case or
var player = new MJPEG.Player('player', 'http://localhost:8080/feed.mjpg');
but a black canvas displays, console log shows started and .

@daleffe
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daleffe commented Nov 4, 2023

For anyone who needs work with MJPEG or JPEG streams/images that are basic auth protected, check this project.

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