Develop Reference

Javascript | MediaRecorder API - Recorded video file on Desktop does not play in Mobile

I am trying to develop a canva-like Insta story creator using Canvas and MediaRecorder
The app is working perfectly on a desktop browser - I am able to download the file, and play it on desktop. However, when I send that file to my mobile, it doesn't play(even on Insta). I figure this is an issue with codecs - but don't know how to solve the same.
This is the function that handles the mediaRecorderAPI
Is there any mime type that I can use, that is universal and can play for any device?
initRecorder () {
var dl = document.querySelector("#dl")
let videoStream = this.canvas.captureStream(60);
if(this.isAudioPresent) {
videoStream.addTrack(this.audioStream.getAudioTracks()[0])
}
let mediaRecorder = new MediaRecorder(videoStream, {
videoBitsPerSecond : 2500000,
mime: 'video/webm'
});
let chunks = [];
mediaRecorder.onstop = function(e) {
var blob = new Blob(chunks, { 'type' : 'video/webm' });
chunks = [];
var videoURL = URL.createObjectURL(blob);
dl.href = videoURL;
};
mediaRecorder.ondataavailable = function(e) {
e.data.size && chunks.push(e.data);
};
mediaRecorder.start();
setTimeout(function (){ mediaRecorder.stop(); },this.storytime);
}
```

Figured this out: Different browsers use different transcoding. Insta only accepts MP4 transcoding. Hence, you need to use either a transcoder on the frontend(ffmpeg.js or wasm version of ffmpeg) or send your data to backend and handle there(which I ended up doing)

How to Convert image URL from server (API / ImageURL) to Base64 in Vue.Js

A lot of reference I see about this problem is about upload file and convert to base64 but in my case I want to convert an Image URL from server and convert it to base64 but I still failed to do it, right now I tried it like this, but it still failed since it doesn't show anything
this is my html:
<div v-if="questionData">
<img class="img-preview-download" :src="questionData.image_url? getBase64Image(questionData.image_url) : 'https://via.placeholder.com/640x360'" alt="img-preview">
</div>
this is my method:
getBase64Image(img) {
console.log("cek base64 : ", btoa(img));
return `data:image/jpeg;base64,${btoa(img)}`;
},
I read some using file reader but isn't it only for file when you upload a data using input? can someone help me to solve this? I'm using Vue.Js for the framework
when I used this method I got result like this:

So this is my answer for my future self, who might be forget and stumble again in this problem!
You can solve it by making a new image and inside that image file, you can add your src so the image can be process when still loading or onload.
Remember!
Since it is you, You might be remove the last image.src = url to get a clean code, but this is important, if you remove that line, image.onload will not be trigger because it will search for the image source. and if you try to use image.srcObject to put it with mediaStream it will give you Resolution Overloaded since you still not find the answer for this problem, it is okay, you can use the image first since your step is to achieve how to get file from Image URL. so this is the method you use to solve this problem:
downloadPreview() {
const el = this.$refs.printMe;
const options = {
type: 'dataURL'
};
this.$html2canvas(el, options).then(data => {
this.output = data;
const a = document.createElement('a');
a.style.display = 'none';
a.href = data;
// this is just optional function to download your file
a.download = `name.jpeg`;
document.body.appendChild(a);
a.click();
});
},
convertImgUrlToBase64(url) {
let self = this;
var image = new Image();
image.setAttribute('crossOrigin', 'anonymous'); // use it if you try in a different origin of your web
image.onload = function () {
var canvas = document.createElement('canvas');
canvas.width = image.width;
canvas.height = image.height;
canvas.getContext('2d').drawImage(this, 0, 0);
canvas.toBlob(
function(source) {
var newImg = document.createElement("img"),
url = URL.createObjectURL(source);
newImg.onload = function() {
// no longer need to read the blob so it's revoked
URL.revokeObjectURL(url);
};
newImg.src = url;
},
"image/jpeg",
1
);
// If you ever stumble at 18 DOM Exception, just use this code to fix it
// let dataUrl = canvas.toDataURL("image/jpeg").replace("image/jpeg", "image/octet-stream");
let dataUrl = canvas.toDataURL("image/jpeg");
console.log("cek inside url : ", url);
if(url === backgroundImg) {
self.assignImageBase64Background(dataUrl);
} else {
self.assignImageBase64(dataUrl);
}
};
image.src = url;
},
assignImageBase64(img) {
this.imgBase64 = img;
},
just for information, I use this library to change the div into image file:
vue-html2canvas
Notes:
If you ever wondering why I give self.assignImageBase64(dataUrl); this function in the end, this is because I still wondering how onload works, and how to return Base64 url to the parent thats why I just assign it again in another function since it easier to do.

JavaScript MediaSource Example

I'm trying to create video player using MediaSource , but I can't make it play while buffering new data. I have this code that downloads the full data then plays it.
var vidElement = document.querySelector('video');
if (window.MediaSource) {
var mediaSource = new MediaSource();
vidElement.src = URL.createObjectURL(mediaSource);
mediaSource.addEventListener('sourceopen', sourceOpen);
} else {
console.log("The Media Source Extensions API is not supported.")
}
function sourceOpen(e) {
URL.revokeObjectURL(vidElement.src);
var mime = 'video/webm; codecs="opus, vp09.00.10.08"';
var mediaSource = e.target;
var sourceBuffer = mediaSource.addSourceBuffer(mime);
var videoUrl = 'droid.webm';
fetch(videoUrl)
.then(function(response) {
return response.arrayBuffer();
})
.then(function(arrayBuffer) {
sourceBuffer.addEventListener('updateend', function(e) {
if (!sourceBuffer.updating && mediaSource.readyState === 'open') {
mediaSource.endOfStream();
}
});
sourceBuffer.appendBuffer(arrayBuffer);
});
}
This code is not working on the local host. I get the MediaSource closed and this line never gets called
mediaSource.endOfStream();
Can any one tell me why the state is closed, please?
Any help about creating player like YouTube or any open source.
and by the way I tried a lot of codes and sources for 2 days now, and it's always the MediaSource giving me errors like the source removed, or not linked.

For starters, on your first line you have a collection...
var V=document.querySelector('video');
Shouldn't that be...
var V=document.querySelector('video')[0];
Before you start operating on it?

Using PDFkit in browser, inserting an image from a link

Is there a simple way to get an image from a url to put in a PDFKit pdf?
I have a PDF being automatically generated in-browser. There's an image I want included, to which I have a URL. The catch is that I'm generating the PDF in-browser. Since I have the URL available from the internet, it seems like there should be an easy way to turn that image into something readable by PDFKit.
Is there a way for Javascript to turn an image URL into a buffer readable by PDFKit?
What I want is what you'd like the following command to do:
doc.image('http://upload.wikimedia.org/wikipedia/commons/0/0c/Cow_female_black_white.jpg')
Thanks in advance. The solutions I found online have your server take in the link, and respond with a buffer. Is this the only way? Or is there a way all in-browser with no http posting?

This is a pretty old question but I'll add my notes since it's the first suggestion when looking for "pdfkit browser image" on Google.
I based my solution on the data uri option supported by PDFKit:
Just pass an image path, buffer, or data uri with base64 encoded data
to the image method along with some optional arguments.
So after a quick look around I found the general approach to get a data uri from an image URL was using canvas, like in this post. Putting it together in PDFKit's interactive browser demo:
function getDataUri(url, callback) {
var image = new Image();
image.crossOrigin = 'anonymous'
image.onload = function () {
var canvas = document.createElement('canvas');
canvas.width = this.naturalWidth; // or 'width' if you want a special/scaled size
canvas.height = this.naturalHeight; // or 'height' if you want a special/scaled size
canvas.getContext('2d').drawImage(this, 0, 0);
// // Get raw image data
// callback(canvas.toDataURL('image/png').replace(/^data:image\/(png|jpg);base64,/, ''));
// ... or get as Data URI
callback(canvas.toDataURL('image/png'));
};
image.src = url;
}
// Usage
getDataUri('http://pdfkit.org/docs/img/14.png', function(dataUri) {
// create a document and pipe to a blob
var doc = new PDFDocument();
var stream = doc.pipe(blobStream());
doc.image(dataUri, 150, 200, {
width: 300
});
// end and display the document in the iframe to the right
doc.end();
stream.on('finish', function() {
iframe.src = stream.toBlobURL('application/pdf');
});
});

I retrieve the image via AJAX as a base64-encoded string, then use the following code to convert the base64-encoded string into a usable buffer:
var data = atob(base64);
var buffer = [];
for (var i = 0; i < data.length; ++i)
buffer.push(data.charCodeAt(i));
buffer._isBuffer = true;
buffer.readUInt16BE = function(offset, noAssert) {
var len = this.length;
if (offset >= len) return;
var val = this[offset] << 8;
if (offset + 1 < len)
val |= this[offset + 1];
return val;
};
pdf.image(buffer);
See also https://github.com/devongovett/pdfkit/issues/354#issuecomment-68666894, where the same issue is discussed as applied to fonts.

I'll weigh my 2 cents on the issue as I just spent a good deal of time getting it to work. It's a medley of answers I've found googling the issue.
var doc = new PDFDocument();
var stream = doc.pipe(blobStream());
var files = {
img1: {
url: 'http://upload.wikimedia.org/wikipedia/commons/0/0c/Cow_female_black_white.jpg',
}
};
Use the above object at a place to store all of the images and other files needed in the pdf.
var filesLoaded = 0;
//helper function to get 'files' object with base64 data
function loadedFile(xhr) {
for (var file in files) {
if (files[file].url === xhr.responseURL) {
var unit8 = new Uint8Array(xhr.response);
var raw = String.fromCharCode.apply(null,unit8);
var b64=btoa(raw);
var dataURI="data:image/jpeg;base64,"+b64;
files[file].data = dataURI;
}
}
filesLoaded += 1;
//Only create pdf after all files have been loaded
if (filesLoaded == Object.keys(files).length) {
showPDF();
}
}
//Initiate xhr requests
for (var file in files) {
files[file].xhr = new XMLHttpRequest();
files[file].xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
loadedFile(this);
}
};
files[file].xhr.responseType = 'arraybuffer';
files[file].xhr.open('GET', files[file].url);
files[file].xhr.send(null);
}
function showPDF() {
doc.image(files.img1.data, 100, 200, {fit: [80, 80]});
doc.end()
}
//IFFE that will download pdf on load
var saveData = (function () {
var a = document.createElement("a");
document.body.appendChild(a);
a.style = "display: none";
return function (blob, fileName) {
var url = window.URL.createObjectURL(blob);
a.href = url;
a.download = fileName;
a.click();
window.URL.revokeObjectURL(url);
};
}());
stream.on('finish', function() {
var blob = stream.toBlob('application/pdf');
saveData(blob, 'aa.pdf');
});
The biggest issue I came across was getting the info from the arraybuffer type to a string with base64 data. I hope this helps!
Here is the js fiddle where most of the xhr code came from.

I did it using NPM package axios to get a base64 encoded buffer:
on the project folder:
npm i axios
code:
var axios = require('axios');
let image = await axios.get("url", {responseType: 'arraybuffer'});
doc.image(image.data, 12, h, {
width: 570,
align: 'center',
valign: 'center'
});

Save to Local File from Blob

I have a difficult question to you, which i'm struggling on for some time now.
I'm looking for a solution, where i can save a file to the users computer, without the local storage, because local storage has 5MB limit. I want the "Save to file"-dialog, but the data i want to save is only available in javascript and i would like to prevent sending the data back to the server and then send it again.
The use-case is, that the service im working on is saving compressed and encrypted chunks of the users data, so the server has no knowledge whats in those chunks and by sending the data back to the server, this would cause 4 times traffic and the server is receiving the unencrypted data, which would render the whole encryption useless.
I found a javascript function to save the data to the users computer with the "Save to file"-dialog, but the work on this has been discontinued and isnt fully supported. It's this: http://www.w3.org/TR/file-writer-api/
So since i have no window.saveAs, what is the way to save data from a Blob-object without sending everything to the server?
Would be great if i could get a hint, what to search for.
I know that this works, because MEGA is doing it, but i want my own solution :)

Your best option is to use a blob url (which is a special url that points to an object in the browser's memory) :
var myBlob = ...;
var blobUrl = URL.createObjectURL(myBlob);
Now you have the choice to simply redirect to this url (window.location.replace(blobUrl)), or to create a link to it. The second solution allows you to specify a default file name :
var link = document.createElement("a"); // Or maybe get it from the current document
link.href = blobUrl;
link.download = "aDefaultFileName.txt";
link.innerHTML = "Click here to download the file";
document.body.appendChild(link); // Or append it whereever you want

FileSaver.js implements saveAs for certain browsers that don't have it
https://github.com/eligrey/FileSaver.js
Tested with FileSaver.js 1.3.8 tested on Chromium 75 and Firefox 68, neither of which have saveAs.
The working principle seems to be to just create an <a element and click it with JavaScript oh the horrors of the web.
Here is a demo that save a blob generated with canvas.toBlob to your download folder with the chosen name mypng.png:
var canvas = document.getElementById("my-canvas");
var ctx = canvas.getContext("2d");
var pixel_size = 1;
function draw() {
console.log("draw");
for (x = 0; x < canvas.width; x += pixel_size) {
for (y = 0; y < canvas.height; y += pixel_size) {
var b = 0.5;
ctx.fillStyle =
"rgba(" +
(x / canvas.width) * 255 + "," +
(y / canvas.height) * 255 + "," +
b * 255 +
",255)"
;
ctx.fillRect(x, y, pixel_size, pixel_size);
}
}
canvas.toBlob(function(blob) {
saveAs(blob, 'mypng.png');
});
}
window.requestAnimationFrame(draw);
<canvas id="my-canvas" width="512" height="512" style="border:1px solid black;"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/FileSaver.js/1.3.8/FileSaver.min.js"></script>
Here is an animated version that downloads multiple images: Convert HTML5 Canvas Sequence to a Video File
See also:
how to save canvas as png image?
JavaScript: Create and save file

HERE is the direct way.
canvas.toBlob(function(blob){
console.log(typeof(blob)) //let you have 'blob' here
var blobUrl = URL.createObjectURL(blob);
var link = document.createElement("a"); // Or maybe get it from the current document
link.href = blobUrl;
link.download = "image.jpg";
link.innerHTML = "Click here to download the file";
document.body.appendChild(link); // Or append it whereever you want
document.querySelector('a').click() //can add an id to be specific if multiple anchor tag, and use #id
}, 'image/jpeg', 1); // JPEG at 100% quality
spent a while to come upto this solution, comment if this helps.
Thanks to Sebastien C's answer.

this node dependence was more utils fs-web;
npm i fs-web
Usage
import * as fs from 'fs-web';
async processFetch(url, file_path = 'cache-web') {
const fileName = `${file_path}/${url.split('/').reverse()[0]}`;
let cache_blob: Blob;
await fs.readString(fileName).then((blob) => {
cache_blob = blob;
}).catch(() => { });
if (!!cache_blob) {
this.prepareBlob(cache_blob);
console.log('FROM CACHE');
} else {
await fetch(url, {
headers: {},
}).then((response: any) => {
return response.blob();
}).then((blob: Blob) => {
fs.writeFile(fileName, blob).then(() => {
return fs.readString(fileName);
});
this.prepareBlob(blob);
});
}
}

From a file picker or input type=file file chooser, save the filename to local storage:
HTML:
<audio id="player1">Your browser does not support the audio element</audio>
JavaScript:
function picksinglefile() {
var fop = new Windows.Storage.Pickers.FileOpenPicker();
fop.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.musicLibrary;
fop.fileTypeFilter.replaceAll([".mp3", ".wav"]);
fop.pickSingleFileAsync().then(function (file) {
if (file) {
// save the file name to local storage
localStorage.setItem("alarmname$", file.name.toString());
} else {
alert("Operation Cancelled");
}
});
}
Then later in your code, when you want to play the file you selected, use the following, which gets the file using only it's name from the music library. (In the UWP package manifest, set your 'Capabilites' to include 'Music Library'.)
var l = Windows.Storage.KnownFolders.musicLibrary;
var f = localStorage.getItem("alarmname$").toString(); // retrieve file by name
l.getFileAsync(f).then(function (file) {
// storagefile file is available, create URL from it
var s = window.URL.createObjectURL(file);
var x = document.getElementById("player1");
x.setAttribute("src", s);
x.play();
});