Develop Reference

Blocked attempt to create a WebMediaPlayer as there are too many WebMediaPlayers already in existence

We are working on a Digital Audio Workstation kind of thing in the browser. We need to work with multiple audio files in a tab. We use new Audio(audioUrl) to be able to play the audio in our own audio mixer. It has been working for us up to now.
With the latest version of Chrome (92), we have the problem where the above code snippet causes the following error:
[Intervention] Blocked attempt to create a WebMediaPlayer as there are too many WebMediaPlayers already in existence. See crbug.com/1144736#c27
I cannot access the bug link provided, it says permission denied. And is there a suggested workaround to handle this?
UPDATE:
I moved away from using HTMLAudioElement to AudioBufferSourceNode. Seems like the only straightforward solution as Chrome team is discussing to limit them anyway. Note: We may need more than 1000 audio clips to be played back. This is in reference to the chromium discussion thread where they are going to increase the number of webmediaplayers to 1000 on the next release for August 5 2021.

Chrome 92 has introduced a limit on number of audio and video tags that can be allocated in a particular tab.
75 for desktop browsers and 40 for mobile browsers.
For now the only solution is to limit the number of audio and video tags created in the page. Try reusing the already allocated audio / video elements.
The number can only be increased by passing the following flag when starting up chrome, for example --max-web-media-player-count=5000
(Of course we cannot expect the end user to do this)
Related Source code here:
https://chromium-review.googlesource.com/c/chromium/src/+/2816118
Edit:
Before deallocating the audio/video elements setting the following seems to force clean up of the element.
mediaElement.remove();
mediaElement.srcObject = null;

const MaxWebMediaPlayerCount = 75;
class VideoProducer {
static #documentForVideo
static createVideo() {
if (!this.#documentForVideo || this.#documentForVideo.videoCount === MaxWebMediaPlayerCount) {
const iframeForVideo = document.body.appendChild(document.createElement('iframe'));
iframeForVideo.style.display = 'none';
iframeForVideo.contentDocument.videoCount = 0;
this.#documentForVideo = iframeForVideo.contentDocument;
}
this.#documentForVideo.videoCount++;
const video = this.#documentForVideo.createElement('video');
return video;
}
foo() {
const video = VideoProducer.createVideo();
// ...
}

Yeah me too it broke my game,
This is what I found as a workaround, hope this helps in the mean time:
function playSound( ) {
var jump_sound = new Audio("./jump.mp3");
jump_sound.play();
jump_sound.onended = function(){
this.currentSrc = null;
this.src = "";
this.srcObject = null;
this.remove();
};
}
Note: it still blocks if there's too many concurrent sound but with this code in place the blocking is temporary.

Chrome version 92.0.4515.131 seems to resolve the issue

Javascript get updated link in real time

I'm new to javascript and I've created a kinda successful extension on chrome for dubtrack I've been trying to figure out for quite awhile how to make my injected script run in real time and grab the latest youtube music video url any help would be much appreciated my extension is very basic and it's not for profit I just made it to play around with javascript and jquery.
Here's the section of code that I'd like to have function in real time.
$('#grab').click(function() {
function getId(url) {
var regExp = /^.*(youtu.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=)([^#\&\?]*).*/;
var match = url.match(regExp);
if (match && match[2].length == 11) {
return match[2];
} else {
return 'error';
}
}
src = $('iframe').attr('src');
setInterval(function() {
src = $('iframe').attr('src');
}, 10000);
window.open('http://youtubeinmp3.com/fetch/?video=http://www.youtube.com/watch?v=' + getId(src), '_blank');
});
Relevant links
GitHub
Chrome Extension
Thank you for taking the time to read my question.

You're bad at explaining (and might want to edit the question to reflect what you want), but basically the problem is this:
You have a YouTube embed in the page, with a particular video ID in src.
When the video changes, that happens without updating the src (by using YT embed API).
Therefore, if you try to grab just the src, it's not the latest video but the first you loaded.
As an extension, I see two ways of trying to solve it:
You could try to initialize the YT API yourself to get a player reference. I don't know if it will break the code of Dubtrack.
You could inject a script in the iframe as well that would somehow extract the video being played in a way other than relying on src.
It's an open problem how to solve it, and the fact that you're basically providing "just" a bookmarklet may be an obstacle.

using the video.js api duration call returns 0 while video is much longer

okay So I'm trying to leverage the video.js project as it's seems pretty amazing!
anyways, im writing my first script that interacts with the api which can be found below. it's basically just supposed to output the current play time to the div current_time , the id of video tag is my_stream anyways here's all my javascript ... the problem im having is playLength=0 and current time never updates when video is playing and remains at 0 (ie. is never more then 0 ) im not sure what im doing wrong here ... the api rules i followed can also be found here video.js api docs
function current_time(){
_V_("my_stream").ready(function(){
var myPlayer = this;
// EXAMPLE:
var playLength = myPlayer.duration();
do
{
var position = myPlayer.currentTime();
var myTextArea = document.getElementById('time_count');
myTextArea.innerHTML = position;
}
while(position < playLength);
});
}
window.onload = current_time
anyhelp from any one who's implemented anything with the api or just see something dumb i've done would be greatly appreciated, thanks!

You're assigning the duration to playLength before playback begins. If that's zero when you assign it, it will remain zero. Check the note in the API doc "NOTE: The video must have started loading before the duration can be known, and in the case of Flash, may not be known until the video starts playing."
It looks like you're only concerned about the duration to work out when the video is playing. It would be far better just to use the timeupdate event instead.
var myPlayer;
var myTextArea = document.getElementById('time_count');
videojs('my_stream').ready(function(){
myPlayer = this;
myPlayer.addEvent('timeupdate', onProgress);
});
function onProgress() {
myTextArea.innerHTML = myPlayer.currentTime();
}
This should execute after the DOM has loaded (with window.onload, or jQuery's $(document).ready()), or go in a script tag in the body after the video and #time_count elements.

I Have sort-of solved this problem bymyself by modifying the code I Had written so it now works like so
function current_time(){
_V_("my_stream").ready(function(){
var myPlayer = this;
var playLength = myPlayer.duration();
var position = myPlayer.currentTime();
var myTextArea = document.getElementById('time_count');
myTextArea.innerHTML = position + "/" + playLength;
t=setTimeout(function() {current_time()},2000);
});
}
... although it seems stupid to poll duration continuosly, I actually don't need this value going forward in development, however both populate properly now once the video is playing so it's kinda a solution. I'm not going to except my own answer right away to see if anyone can solve this a better way, or if you can explain why video.js changes the id tag and how to properly deal with it i'll give you an up vote and accept your answer if it all makes sense to me.

window.location called too often?

I am trying to intercept the window.location changes to do some native work in Android app. To ve more specific, I overwrite the call in WebViewClient:
public boolean shouldOverrideUrlLoading(WebView view, String url)
to look for anything start with "native://". The JavaScript code is like this.
function callNative() {
window.location = "native://doSomeNativeWork()";
}
function callNativeManyTimes(count) {
for(i = 0 ; i < count ; i ++) {
callNative();
}
}
DoSomeNativeWork<br/>
The problem I am seeing is that if I call "window.location = something" many time very quickly (like in the code above) , I will only get one call inside the WebViewClient on the native code side. If I make the call 50ms apart, I will get everyone of them. I am thinking that the browser is doing some optimization around this.
I think I can solve this problem like this: do not use window.location, change to embed a native object to javascript, and call methods on that object in javascript. I am just wondering why this is happening. Can someone more familiar wit JS to share some insight?
Thanks

I had exact the same problem. You can do that by creating iframes. I create iframes with the native urls and then I delete the iframe after 2 seconds just so we don't have too many laying around on the DOM. Worked like a charm to me. You can create as many iframes as you want.
I also included a cache buster on the iframe url, even though I'm not sure it's needed. Better safe then sorry.
function callNative(url){
var _frame = document.createElement('iframe');
_frame.width=0; _frame.height=0;_frame.frameBorder=0;
document.body.appendChild(_frame);
if (url.indexOf('?') >= 0){
url = url + "&cb=";
}else{
url = url + "?cb=";
}
_frame.src = url + Math.round(Math.random()*1e16);
// Remove the iframe
setTimeout(function(){document.body.removeChild(_frame);}, 2000);
}
function callNativeManyTimes(count) {
for(i = 0 ; i < count ; i ++) {
callNative('native://doSomeNativeWork()');
}
}
DoSomeNativeWork<br/>
Note that I used the approach above on iOS. Not sure if it's exactly the same on Android, but from judging the question and other answer I guess it's the same.

I would guess that loading a URL is asynchronous (it would probably be a bad idea to block the execution of a script until a URL has been resolved). As such, setting window.location will presumably only queue up the loading of the new URL, which will be done in a different thread.
Waiting 50ms is a hack that may or may not work. You need to find a different approach. You need something that guarantees that each one of those URLs will be resolved. If the order doesn't matter, you could just use images, like somebody suggested. Otherwise, you could use a native JavaScript interface (which is probably the better approach).

The definitive best way to preload images using JavaScript/jQuery?

I'm fully aware that this question has been asked and answered everywhere, both on SO and off. However, every time there seems to be a different answer, e.g. this, this and that.
I don't care whether it's using jQuery or not - what's important is that it works, and is cross-browser.]
So, what is the best way to preload images?

Unfortunately, that depends on your purpose.
If you plan to use the images for purposes of style, your best bet is to use sprites.
http://www.alistapart.com/articles/sprites2
However, if you plan to use the images in <img> tags, then you'll want to pre-load them with
function preload(sources)
{
var images = [];
for (i = 0, length = sources.length; i < length; ++i) {
images[i] = new Image();
images[i].src = sources[i];
}
}
(modified source taken from What is the best way to preload multiple images in JavaScript?)
using new Image() does not involve the expense of using DOM methods but a new request for the image specified will be added to the queue. As the image is, at this point, not actually added to the page, there is no re-rendering involved. I would recommend, however, adding this to the end of your page (as all of your scripts should be, when possible) to prevent it from holding up more critical elements.
Edit: Edited to reflect comment quite correctly pointing out that separate Image objects are required to work properly. Thanks, and my bad for not checking it more closely.
Edit2: edited to make the reusability more obvious
Edit 3 (3 years later):
Due to changes in how browsers handle non-visible images (display:none or, as in this answer, never appended to the document) a new approach to pre-loading is preferred.
You can use an Ajax request to force early retrieval of images. Using jQuery, for example:
jQuery.get(source);
Or in the context of our previous example, you could do:
function preload(sources)
{
jQuery.each(sources, function(i,source) { jQuery.get(source); });
}
Note that this doesn't apply to the case of sprites which are fine as-is. This is just for things like photo galleries or sliders/carousels with images where the images aren't loading because they are not visible initially.
Also note that this method does not work for IE (ajax is normally not used to retrieve image data).

Spriting
As others have mentioned, spriting works quite well for a variety of reasons, however, it's not as good as its made out to be.
On the upside, you end up making only one HTTP request for your images. YMMV though.
On the down side you are loading everything in one HTTP request. Since most current browsers are limited to 2 concurrent connections the image request can block other requests. Hence YMMV and something like your menu background might not render for a bit.
Multiple images share the same color palette so there is some saving but this is not always the case and even so it's negligible.
Compression is improved because there is more shared data between images.
Dealing with irregular shapes is tricky though. Combining all new images into the new one is another annoyance.
Low jack approach using <img> tags
If you are looking for the most definitive solution then you should go with the low-jack approach which I still prefer. Create <img> links to the images at the end of your document and set the width and height to 1x1 pixel and additionally put them in a hidden div. If they are at the end of the page, they will be loaded after other content.

As of January 2013 none of the methods described here worked for me, so here's what did instead, tested and working with Chrome 25 and Firefox 18. Uses jQuery and this plugin to work around the load event quirks:
function preload(sources, callback) {
if(sources.length) {
var preloaderDiv = $('<div style="display: none;"></div>').prependTo(document.body);
$.each(sources, function(i,source) {
$("<img/>").attr("src", source).appendTo(preloaderDiv);
if(i == (sources.length-1)) {
$(preloaderDiv).imagesLoaded(function() {
$(this).remove();
if(callback) callback();
});
}
});
} else {
if(callback) callback();
}
}
Usage:
preload(['/img/a.png', '/img/b.png', '/img/c.png'], function() {
console.log("done");
});
Note that you'll get mixed results if the cache is disabled, which it is by default on Chrome when the developer tools are open, so keep that in mind.

In my opinion, using Multipart XMLHttpRequest introduced by some libraries will be a preferred solution in the following years. However IE < v8, still don't support data:uri (even IE8 has limited support, allowing up to 32kb). Here is an implementation of parallel image preloading - http://code.google.com/p/core-framework/wiki/ImagePreloading , it's bundled in framework but still worth taking a look.

This was from a long time ago so I dont know how many people are still interested in preloading an image.
My solution was even more simple.
I just used CSS.
#hidden_preload {
height: 1px;
left: -20000px;
position: absolute;
top: -20000px;
width: 1px;
}

Here goes my simple solution with a fade in on the image after it is loaded.
function preloadImage(_imgUrl, _container){
var image = new Image();
image.src = _imgUrl;
image.onload = function(){
$(_container).fadeTo(500, 1);
};
}

For my use case I had a carousel with full screen images that I wanted to preload. However since the images display in order, and could take a few seconds each to load, it's important that I load them in order, sequentially.
For this I used the async library's waterfall() method (https://github.com/caolan/async#waterfall)
// Preload all images in the carousel in order.
image_preload_array = [];
$('div.carousel-image').each(function(){
var url = $(this).data('image-url');
image_preload_array.push(function(callback) {
var $img = $('<img/>')
$img.load(function() {
callback(null);
})[0].src = url;
});
});
async.waterfall(image_preload_array);
This works by creating an array of functions, each function is passed the parameter callback() which it needs to execute in order to call the next function in the array. The first parameter of callback() is an error message, which will exit the sequence if a non-null value is provided, so we pass null each time.

See this:
http://www.mattfarina.com/2007/02/01/preloading_images_with_jquery
Related question on SO:
jquery hidden preload