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Can't figure out how to fix this: "Uncaught TypeError (webcam.snap is not a function)" <-- javascript

I have a JavaScript script that I am getting an error for that I can't figure out. I am trying to take a picture of the webcam feed using JavaScript
The error is:
Uncaught TypeError: webcam.snap is not a function
I am using webcam.js to take the snapshot.
Here is my JavaScript code:
<script>
var video = document.createElement("video");
var canvasElement = document.getElementById("canvas");
var canvas = canvasElement.getContext("2d");
var loadingMessage = document.getElementById("loadingMessage");
var outputContainer = document.getElementById("output");
var outputMessage = document.getElementById("outputMessage");
var outputData = document.getElementById("outputData");
const jsQR = require("jsqr");
function drawLine(begin, end, color) {
canvas.beginPath();
canvas.moveTo(begin.x, begin.y);
canvas.lineTo(end.x, end.y);
canvas.lineWidth = 4;
canvas.strokeStyle = color;
canvas.stroke();
}
// Use facingMode: environment to attemt to get the front camera on phones
navigator.mediaDevices.getUserMedia({ video: { facingMode: "environment" } }).then(function(stream) {
video.srcObject = stream;
video.setAttribute("playsinline", true); // required to tell iOS safari we don't want fullscreen
video.play();
requestAnimationFrame(tick);
});
function tick() {
loadingMessage.innerText = "⌛ Loading video..."
if (video.readyState === video.HAVE_ENOUGH_DATA) {
loadingMessage.hidden = true;
canvasElement.hidden = false;
outputContainer.hidden = false;
canvasElement.height = video.videoHeight;
canvasElement.width = video.videoWidth;
canvas.drawImage(video, 0, 0, canvasElement.width, canvasElement.height);
var imageData = canvas.getImageData(0, 0, canvasElement.width, canvasElement.height);
var code = jsQR(imageData.data, imageData.width, imageData.height, {
inversionAttempts: "invertFirst",
});
if (code) {
drawLine(code.location.topLeftCorner, code.location.topRightCorner, "#FF3B58");
drawLine(code.location.topRightCorner, code.location.bottomRightCorner, "#FF3B58");
drawLine(code.location.bottomRightCorner, code.location.bottomLeftCorner, "#FF3B58");
drawLine(code.location.bottomLeftCorner, code.location.topLeftCorner, "#FF3B58");
outputMessage.hidden = true;
outputData.parentElement.hidden = false;
outputData.innerText = code.data;
takeSnapShot();
}
else {
outputMessage.hidden = false;
outputData.parentElement.hidden = true;
}
}
requestAnimationFrame(tick);
}
// TAKE A SNAPSHOT.
takeSnapShot = function () {
webcam.snap(function (data_uri) {
downloadImage('video', data_uri);
});
}
// DOWNLOAD THE IMAGE.
downloadImage = function (name, datauri) {
var a = document.createElement('a');
a.setAttribute('download', name + '.png');
a.setAttribute('href', datauri);
a.click();
}
</script>
This is the first line that causes a problem:
webcam.snap(function (data_uri) {
downloadImage('video', data_uri);
});
This is the second line that causes a problem:
takeSnapShot();
how do I correct this properly?
****** UPDATE ******
The version of webcam.js I am using is WebcamJS v1.0.26. My application is a Django application that launches the HTML file as defined in main.js.
snap: function(user_callback, user_canvas) {
// use global callback and canvas if not defined as parameter
if (!user_callback) user_callback = this.params.user_callback;
if (!user_canvas) user_canvas = this.params.user_canvas;
// take snapshot and return image data uri
var self = this;
var params = this.params;
if (!this.loaded) return this.dispatch('error', new WebcamError("Webcam is not loaded yet"));
// if (!this.live) return this.dispatch('error', new WebcamError("Webcam is not live yet"));
if (!user_callback) return this.dispatch('error', new WebcamError("Please provide a callback function or canvas to snap()"));
// if we have an active preview freeze, use that
if (this.preview_active) {
this.savePreview( user_callback, user_canvas );
return null;
}
// create offscreen canvas element to hold pixels
var canvas = document.createElement('canvas');
canvas.width = this.params.dest_width;
canvas.height = this.params.dest_height;
var context = canvas.getContext('2d');
// flip canvas horizontally if desired
if (this.params.flip_horiz) {
context.translate( params.dest_width, 0 );
context.scale( -1, 1 );
}
// create inline function, called after image load (flash) or immediately (native)
var func = function() {
// render image if needed (flash)
if (this.src && this.width && this.height) {
context.drawImage(this, 0, 0, params.dest_width, params.dest_height);
}
// crop if desired
if (params.crop_width && params.crop_height) {
var crop_canvas = document.createElement('canvas');
crop_canvas.width = params.crop_width;
crop_canvas.height = params.crop_height;
var crop_context = crop_canvas.getContext('2d');
crop_context.drawImage( canvas,
Math.floor( (params.dest_width / 2) - (params.crop_width / 2) ),
Math.floor( (params.dest_height / 2) - (params.crop_height / 2) ),
params.crop_width,
params.crop_height,
0,
0,
params.crop_width,
params.crop_height
);
// swap canvases
context = crop_context;
canvas = crop_canvas;
}
// render to user canvas if desired
if (user_canvas) {
var user_context = user_canvas.getContext('2d');
user_context.drawImage( canvas, 0, 0 );
}
// fire user callback if desired
user_callback(
user_canvas ? null : canvas.toDataURL('image/' + params.image_format, params.jpeg_quality / 100 ),
canvas,
context
);
};
// grab image frame from userMedia or flash movie
if (this.userMedia) {
// native implementation
context.drawImage(this.video, 0, 0, this.params.dest_width, this.params.dest_height);
// fire callback right away
func();
}
else if (this.iOS) {
var div = document.getElementById(this.container.id+'-ios_div');
var img = document.getElementById(this.container.id+'-ios_img');
var input = document.getElementById(this.container.id+'-ios_input');
// function for handle snapshot event (call user_callback and reset the interface)
iFunc = function(event) {
func.call(img);
img.removeEventListener('load', iFunc);
div.style.backgroundImage = 'none';
img.removeAttribute('src');
input.value = null;
};
if (!input.value) {
// No image selected yet, activate input field
img.addEventListener('load', iFunc);
input.style.display = 'block';
input.focus();
input.click();
input.style.display = 'none';
} else {
// Image already selected
iFunc(null);
}
}
else {
// flash fallback
var raw_data = this.getMovie()._snap();
// render to image, fire callback when complete
var img = new Image();
img.onload = func;
img.src = 'data:image/'+this.params.image_format+';base64,' + raw_data;
}
return null;
},

Your implementation doesn't need Webcamjs, because you're using navigator media devices.
You can either use WebcamJS by initializing it at first and attaching it to some canvas, like in the following code
Webcam.set({
width: 320,
height: 240,
image_format: 'jpeg',
jpeg_quality: 90
});
Webcam.attach( '#my_camera' );
Or you can update your takeSnapShot function to the following :
takeSnapShot = function () {
downloadImage('video',canvasElement.toDataURL())
// Webcam.snap(function (data_uri) {
// downloadImage('video', data_uri);
// });
}
Here's a working example based on your code https://codepen.io/majdsalloum/pen/RwVKBbK

It seems like either:
the webcam's code are missing (not imported)
in this case you need to first call the script from the URL and add it with script tag
<script src="WEBCAM_JS_SOURCE">
or
they are imported, but used with typo. From the webcam source code it is defined as:
var Webcam = {
version: '1.0.26',
// globals
...
};
so you should use with a capital one.

javascript canvas capture screenshot of camera issue in Samsung Browser

Well, I'm having a very weird issue that's only happening on Samsung Browser. On Chrome and other browsers, this works well.
When I take a snapshot of a current frame of a video (Currently the mobile camera) on javascript I get the image with distortion and generally bad.
The code that takes the snapshot is:
function takeSnapshot() {
// Here we're using a trick that involves a hidden canvas element.
video.pause();
var hidden_canvas = document.createElement('canvas'),
context = hidden_canvas.getContext('2d');
var width = video.videoWidth,
height = video.videoHeight;
if (width && height) {
// Setup a canvas with the same dimensions as the video.
hidden_canvas.width = width;
hidden_canvas.height = height;
// Make a copy of the current frame in the video on the canvas.
context.drawImage(video, 0, 0, width, height);
// Turn the canvas image into a dataURL that can be used as a src for our photo.
return hidden_canvas.toDataURL('image/jpeg');
}
}
Do I'm missing something else to make it work in Samsung Browser? Or I just put a message that this is not compatible with this browser?
Currently tested on Samsung Galaxy S9, Android 10.
------------- Update
I found what is causing the image to be captured badly.
I'm using custom size for the image, in this case, is a horizontal rectangle.
I do this when init the video:
var w = 2000; // This renders the video as a horizontal rectangle, this does the issue.
var h = 1200;
var userAgent = (typeof navigator !== 'undefined' && navigator.userAgent) || '';
var isSamsungBrowser = userAgent.indexOf('SamsungBrowser') >= 0;
// Quick fix:
if(SamsungBrowser){ // If I render as vertical renctangle, the issue is gone.
w = 1200;
h = 2000;
}
navigator.getMedia(
{
video:
{
deviceId: videoSource ? { exact: videoSource } : undefined,
width: { ideal: h },
height: { ideal: w }
}
},
// Success Callback
function (stream) {
// Create an object URL for the video stream and
// set it as src of our HTLM video element.
try {
currentStream = stream;
video.srcObject = stream;
} catch (error) {
video.src = window.URL.createObjectURL(stream);
}
window.stream = stream;
// Play the video element to start the stream.
video.play();
video.onplay = function () {
showVideo();
};
}

jsQR Javascript mediadevices undefined

I am trying to implement the jsQR javascript library from git: jsQR
I am testing on Safari 13.0.4 and when i run their demo found on their webpage it runs with no problems.
Now when i implement the same exact code (copy&paste) from the demo's inspector to my page i get the message TypeError: undefined is not an object (evaluating 'navigator.mediaDevices.getUserMedia') which after some console printing the actual undefined object is navigator.mediaDevices this is strange since their demo is working i do not think it is a browser issue.
Additionally i run my page on firefox and it works perfectly fine.
What might be the problem?
Here is the code i have (it is the exact as demo anyway):
Javascript:
var video = document.createElement("video");
var canvasElement = document.getElementById("canvas");
var canvas = canvasElement.getContext("2d");
var loadingMessage = document.getElementById("loadingMessage");
var outputContainer = document.getElementById("output");
var outputMessage = document.getElementById("outputMessage");
var outputData = document.getElementById("outputData");
function drawLine(begin, end, color) {
canvas.beginPath();
canvas.moveTo(begin.x, begin.y);
canvas.lineTo(end.x, end.y);
canvas.lineWidth = 4;
canvas.strokeStyle = color;
canvas.stroke();
}
$(document).ready(function () {
console.log(navigator.mediaDevices);
})
// Use facingMode: environment to attemt to get the front camera on phones
navigator.mediaDevices.getUserMedia({ video: { facingMode: "environment" } }).then(function(stream) {
video.srcObject = stream;
video.setAttribute("playsinline", true); // required to tell iOS safari we don't want fullscreen
video.play();
requestAnimationFrame(tick);
});
function tick() {
loadingMessage.innerText = "⌛ Loading video..."
if (video.readyState === video.HAVE_ENOUGH_DATA) {
loadingMessage.hidden = true;
canvasElement.hidden = false;
outputContainer.hidden = false;
canvasElement.height = video.videoHeight;
canvasElement.width = video.videoWidth;
canvas.drawImage(video, 0, 0, canvasElement.width, canvasElement.height);
var imageData = canvas.getImageData(0, 0, canvasElement.width, canvasElement.height);
var code = jsQR(imageData.data, imageData.width, imageData.height, {
inversionAttempts: "dontInvert",
});
if (code) {
drawLine(code.location.topLeftCorner, code.location.topRightCorner, "#FF3B58");
drawLine(code.location.topRightCorner, code.location.bottomRightCorner, "#FF3B58");
drawLine(code.location.bottomRightCorner, code.location.bottomLeftCorner, "#FF3B58");
drawLine(code.location.bottomLeftCorner, code.location.topLeftCorner, "#FF3B58");
outputMessage.hidden = true;
outputData.parentElement.hidden = false;
outputData.innerText = code.data;
} else {
outputMessage.hidden = false;
outputData.parentElement.hidden = true;
}
}
requestAnimationFrame(tick);
}
Html:
<div id="loadingMessage">🎥 Unable to access video stream (please make sure you have a webcam enabled)</div>
<canvas id="canvas" hidden></canvas>
<div id="output" hidden>
<div id="outputMessage">No QR code detected.</div>
<div hidden><b>Data:</b> <span id="outputData"></span></div>
</div>

Solved it. The development server is not secure and thus safari does not allow the use of WebRTC on insecure connections.
To allow the use (on safari at least) you have to go to Develop>WebRTC>Allow media capture on insecure sites.

How do I create a thumbnail for each video after uploading multiple selected videos

I'm trying to create a thumbnail preview of several video files (mp4.3gp) of dropzone plugin.
And I want to create a thumbnail of each video selected at the input (if there are 5 videos, create 5 thumbnails). I've seen many implementations, but none with multiple contexts.
Any help is appreciated. Thanks.
// added file video in dropzone plugin
myDropzone.on('addedfile', function(origFile) {
var fileReader = new FileReader();
fileReader.addEventListener("load", function(event) {
var origFileIndex = myDropzone.files.indexOf(origFile);// FileList object
myDropzone.files[origFileIndex].status = Dropzone.ADDED;
var blob = new Blob([fileReader.result], {type: origFile.type});
console.log(blob)
var url = URL.createObjectURL(blob);
var video = document.createElement('video');//added now
var timeupdate = function() {
if (snapImage()) {
video.removeEventListener('timeupdate', timeupdate);
video.pause();
}
};
video.addEventListener('loadeddata', function() {
if (snapImage()) {
video.removeEventListener('timeupdate', timeupdate);
}
});
// Only process video files
if (!origFile.type.match(/mp4|MP4/)) {
myDropzone.enqueueFile(origFile);
return;
}
var snapImage = function() {
var canvas = document.createElement('canvas');
canvas.width = video.videoWidth;
canvas.height = video.videoHeight;
canvas.getContext('2d').drawImage(video, 0, 0, canvas.width, canvas.height);
var arrText = new Array();
var image = canvas.toDataURL();
var success = image.length > 100000;
if (success) {
var img = document.getElementsByClassName('imgthumbnail');
var l = img.length;
$.each(img,function(){
arrText.push(image);
});
for(var i=0; i < l; i++){
var t = img[i];
t.src = arrText[i];// add `src image`
}
URL.revokeObjectURL(url);
}
return success;
};
video.addEventListener('timeupdate', timeupdate);
video.preload = 'metadata';
video.src = url;
// Load video in Safari / IE11
video.muted = true;
video.playsInline = true;
video.play();
}, false);
fileReader.readAsArrayBuffer(origFile);
});
After uploading multiple video files, a thumbnail of the video is shared for each video.

After attaching src to variable t you forgot to add it to DOM. While preview was captured, it was not displayed anywhere. And img element is required to use "src" attribute (src won't work on div).
You could create img element and append it to .imgthumbnail div:
$('<img>', {'src': arrText[i]}).appendTo('.imgthumbnail');
Alternatively, you could pass thumbnail to Dropzone and display it in uploaded file block:
myDropzone.emit("thumbnail", origFile, arrText[i]);
In this case you'll probably want to make some style adjustments to correctly fit thumbnail in Dropzone block.
To process 3gp files too, don't forget to add 3gp extensions to type.match selector.

HTML5 Video with Dynamic Thumbnails

I have a problem, when creating thumbnails. The cross-domain problem I solved with the help of html2canvas PHP proxy.
No error message in the Console. But that Thumnbnails unfortunately are not visible, transparent or white.
Output cut in the source code:
<img src="data:image/png;base64,iVBORw0KGgoAAAA.......Output cut in the source code:NSUhEUgAABN8AAAS4=" width="120">
The script:
<script>
var video = document.getElementById("thumb");
video.addEventListener("loadedmetadata", initScreenshot);
video.addEventListener("playing", startScreenshot);
video.addEventListener("pause", stopScreenshot);
video.addEventListener("ended", stopScreenshot);
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var ssContainer = document.getElementById("screenShots");
var videoHeight, videoWidth;
var drawTimer = null;
function initScreenshot() {
videoHeight = video.videoHeight;
videoWidth = video.videoWidth;
}
function startScreenshot() {
if (drawTimer == null) {
drawTimer = setInterval(grabScreenshot, 1000);
}
}
function stopScreenshot() {
if (drawTimer) {
clearInterval(drawTimer);
drawTimer = null;
}
}
function grabScreenshot() {
ctx.drawImage(video, 0, 0, videoWidth, videoHeight);
convert(document.getElementById("thumb-parent"));
}
function convert(target) {
html2canvas(target, {
"proxy": "../html2canvasproxy.php",
"logging": true, //Enable log (use Web Console for get Errors and Warnings)
"onrendered": function(canvas) {
var img = new Image();
img.onload = function () {
img.onload = null;
img.width = 120;
document.getElementById("screenShots").appendChild(img);
};
img.src = canvas.toDataURL("image/png");
}
});
}

From the looks of things, it's because the browser considers your canvas 'tainted' - using the example you provided above, I've let the video run a little, then tried to log the toDataURL output:
console.log(canvas.toDataURL());
VM1344:2 Uncaught DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.
My suspicion is that is becuase the video is being loaded from a third party URL.
Try loading the video from the same domain as the HTML code, and see if that works