Develop Reference

Create Seamless Loop of Audio - Web

I want to create a seamless loop of an audio file. But in all approaches I used so far, there was a noticeable gap between end & start.
This is what I tried so far:
First approach was to use the audio in the HTML and it loops but there is still a noticeable delay when going from the end of the track to the beginning.
<audio loop autoplay>
<source src="audio.mp3" type="audio/mpeg">
<audio>
Then I tried it from JavaScript with the same result:
let myAudio = new Audio(file);
myAudio.loop = true;
myAudio.play();
After that I tried this (according to this answer)
myAudio.addEventListener(
'timeupdate',
function() {
var buffer = .44;
if (this.currentTime > this.duration - buffer) {
this.currentTime = 0;
this.play();
}
},
false
);
I played around with the buffer but I only got it to reduce the gap but not leave it out entirely.
I turned to the library SeamlessLoop (GitHub) and got it to work to loop seamlessly in Chromium browsers (but not in the latest Safari. Didn't test in other browsers). Code I used for that:
let loop = new SeamlessLoop();
// My File is 58 Seconds long. Btw there aren't any gaps in the file.
loop.addUri(file, 58000, 'sound1');
loop.callback(soundsLoaded);
function soundsLoaded() {
let n = 1;
loop.start('sound' + n);
}
EDIT: I tried another approach: Looping it trough two different audio elements:
var current_player = "a";
var player_a = document.createElement("audio");
var player_b = document.createElement("audio");
player_a.src = "sounds/back_music.ogg";
player_b.src = player_a.src;
function loopIt(){
var player = null;
if(current_player == "a"){
player = player_b;
current_player = "b";
}
else{
player = player_a;
current_player = "a";
}
player.play();
/*
3104.897 is the length of the audio clip in milliseconds.
Received from player.duration.
This is a different file than the first one
*/
setTimeout(loopIt, 3104.897);
}
loopIt();
But as milliseconds in browsers are not consistent or granular enough this doesn't work too well but it does work much better than the normal "loop" property of the audio.
Can anyone guide me into the right direction to loop the audio seamlessly?

You can use the Web Audio API instead. There are a couple of caveats with this, but it will allow you to loop accurately down to the single sample level.
The caveats are that you have to load the entire file into memory. This may not be practical with large files. If the files are only a few seconds it should however not be any problem.
The second is that you have to write control buttons manually (if needed) as the API has a low-level approach. This means play, pause/stop, mute, volume etc. Scanning and possibly pausing can be a challenge of their own.
And lastly, not all browsers support Web Audio API - in this case you will have to fallback to the regular Audio API or even Flash, but if your target is modern browsers this should not be a major problem nowadays.
Example
This will load a 4 bar drum-loop and play without any gap when looped. The main steps are:
It loads the audio from a CORS enabled source (this is important, either use the same domain as your page or set up the external server to allow for cross-origin usage as Dropbox does for us in this example).
AudioContext then decodes the loaded file
The decoded file is used for the source node
The source node is connected to an output
Looping is enabled and the buffer is played from memory.
var actx = new (AudioContext || webkitAudioContext)(),
src = "https://dl.dropboxusercontent.com/s/fdcf2lwsa748qav/drum44.wav",
audioData, srcNode; // global so we can access them from handlers
// Load some audio (CORS need to be allowed or we won't be able to decode the data)
fetch(src, {mode: "cors"}).then(function(resp) {return resp.arrayBuffer()}).then(decode);
// Decode the audio file, then start the show
function decode(buffer) {
actx.decodeAudioData(buffer, playLoop);
}
// Sets up a new source node as needed as stopping will render current invalid
function playLoop(abuffer) {
if (!audioData) audioData = abuffer; // create a reference for control buttons
srcNode = actx.createBufferSource(); // create audio source
srcNode.buffer = abuffer; // use decoded buffer
srcNode.connect(actx.destination); // create output
srcNode.loop = true; // takes care of perfect looping
srcNode.start(); // play...
}
// Simple example control
document.querySelector("button").onclick = function() {
if (srcNode) {
srcNode.stop();
srcNode = null;
this.innerText = "Play";
} else {
playLoop(audioData);
this.innerText = "Stop";
}
};
<button>Stop</button>

There is a very simple solution for that, just use loopify it makes use of the html5 web audio api and works perfectly well with many formats, not only wav as the dev says.
<script src="loopify.js" type="text/javascript"></script>
<script>
loopify("yourfile.mp3|ogg|webm|flac",ready);
function ready(err,loop){
if (err) {
console.warn(err);
}
loop.play();
}
</script>
This will automatically play the file, if you want to have start and stop buttons for example take a look at his demo

How to determine if playing HTML5 audio is actually making sound?

For the purposes of a project I am working, I want to find out via the JS console if the <audio> tag found on facebook.com is playing audio or not. (I can then move this code into a Chrome extension and also apply it against other websites such as silent HTML5 ads.)
You can find the element by typing:
$$("audio")[0]
I have used the following code (adapted from this jsfiddle which I found during a search) to show when different event listeners are called:
var audio = $$("audio")[0];
var events = 'abort,canplay,canplaythrough,durationchange,emptied,ended,error,loadeddata,loadedmetadata,loadstart,pause,play,playing,progress,ratechange,seeked,seeking,stalled,suspend,timeupdate,volumechange,waiting'.split(',');
// event handler
var onEvent = function(e) {
console.log(e.type);
};
// add event listener to audio for all events
for (var i = 0, len = events.length; i < len; i++) {
audio.addEventListener(events[i], onEvent, false);
}
I would then play the audio by typing:
$$("audio")[0].play();
If I check $$("audio")[0].paused, it will show false, but I haven't found any properties or events that would indicate whether it played sound or not. (I wouldn't expect it to here since I don't think it has audio data to play, but if there was a way to check, I could compare that with an audio element that does play sound.)
Also, I have tried sending myself a message from an incognito tab and don't see a trace of this happening. (I assume the audio element gets used for that.)
Help is appreciated.

To check if an HTMLMediaElement (either video or audio) has ever been played on the page, the best solution is to check for its played attribute.
This will return a TimeRanges object that you can as well use to get how much of the media has been played.
If it has never been played, then the length property of this TimeRanges object will be set to 0 :
if(audioElement.played.length){
// This media has already been played
}else{
// Never
}

Why isn't my audio rewinding?

I'm having a bit of trouble rewinding audio in Javascript. I basically have a countdown that beeps each second as it gets towards the end of the countdown.
I tried using;
var bip = new Audio("http://www.soundjay.com/button/beep-7.wav");
bip.play();
but it didn't beep every second which I'm guessing has something to do withit having to load a new sound every second. I then tried loading the sound externally and triggering it with the following code.
bip.pause();
bip.currentTime = 0;
console.log(bip.currentTime);
bip.play();
but this only plays the sound once then completely fails to rewind it (this is shown by the console logging a time of 0.19 seconds after the first playthrough).
Is there something I'm missing here?

In google chrome I noticed that it only works if you have the audio file in same domain. I have no problems if the audio file is in same domain. Event setting .currentTime works.
Cross-domain:
var bip = new Audio("http://www.soundjay.com/button/beep-7.wav");
bip.play();
bip.currentTime; //0.10950099676847458
bip.currentTime = 0;
bip.currentTime; //0.10950099676847458
Same-domain:
var bip = new Audio("beep-7.wav");
bip.play();
bip.currentTime; //0.10950099676847458
bip.currentTime = 0;
bip.currentTime; //0
I tried googling for a while and could find nothing in specs about this or even any discussion.

when I want rewind I simply load the audio again:
my_audio.load()
*btw, I also use a eventlistener for 'canplay' to trigger the my_audio.play(). It seems that this is necessary in android, and maybe other devices also*

To further dsdsdsdsd's answer with a bit of paint-by-numbers for the "whole shebang"
NOTE: In my app, loc1 is a dummy that refers to the song's stored location
// ... code before ...
tune = new Audio(loc1); // First, create audio event using js
// set up "song's over' event listener & action
tune.addEventListener('ended', function(){
tune.load(); //reload audio event (and reset currentTime!)
tune.play(); //play audio event for subsequent 'ended' events
},false);
tune.play(); // plays it the first time thru
// ... code after ...
I spent days and days trying to figure out what I was doing wrong, but it all works fine now... at least on the desktop browsers...

As of Chrome version 37.0.2062.120 m, the behaviour described by #Esailija has not changed.
I workaround this issue by encoding the audio data in base64 encoding and feed the data to Audio() using data: URL.
Test code:
snd = new Audio('data:audio/ogg;base64,[...base64 encoded data...]');
snd.onloadeddata = function() {
snd.currentTime = 0;
snd.play();
setTimeout(function() {
snd.currentTime = 0;
snd.play();
}, 200);
};
(I am surprised that there are no bug reports or references on this matter... or maybe my Google-fu is not strong enough.)

Proper onload for <audio>

I've been looking around and I'm starting to worry that this isn't possible.
Is there any way to make a standard <audio> tag with fallbacks...
<audio>
<source src='song.ogg' type='audio/ogg'></source>
<source src='song.mp3' type='audio/mp3'></source>
</audio>
...have an onload event. I've looked around and all I could find are some hacks that may or may not work (they don't for me on Chrome) and the canplaythrough event.
The reason I want this is because I am making a presentation that has lots of audio clips to play at certain points. I don't want the presentation to start until all of the audio is loaded (otherwise things could get out of sync). I want the clips to be loaded 1 at a time so that I can create a sort of loading bar. I really don't want to resort to using Flash sound because this is supposed to demonstrate pure web technologies.
So basically I've got this one loadAudio function that cycles through the array of audio files to be loaded audioQueue. loadAudio is called once and then it calls itself until all the files are loaded.
Problem is I haven't found the correct event to trigger loading the next file.
loadAudio = function(index)
{
mer = audioQueue[index];
var ob = "<audio id='" + mer + "'><source src='resources/sounds/" + mer + ".ogg' type='audio/ogg'></source><source src='resources/sounds/" + mer + ".mp3' type='audio/mp3'></source></audio>";
$("#audios").append(ob);
$("#" + mer).get(0).addEventListener('A WORKING EVENT RIGHT HERE WOULD BE NICE', function() { alert("loaded");
if (index + 1 < audioQueue) { loadAudio(index + 1); } }, false);
}
So. Any chance for a proper audio onload? I'm basically willing to do anything as long as it's still all HTML and Javascript.

You can use the loadeddata-MediaEvent. For example you can put all of your audio files in an Array and do something like:
var files = ['a.mp3', 'b.mp3'];
$.each(files, function() {
$(new Audio())
.on('loadeddata', function() {
var i = files.indexOf(this);
files.splice(i, 1);
if (!files.length) {
alert('Preloading done!');
}
})
.attr('src', this);
});
EDIT: this would a little more modern approach as of 2016:
var files = ['a.mp3','b.mp3'];
Promise
.all(files.map(function(file) {
return new Promise(function(resolve) {
var tmp = new Audio();
tmp.src = file;
tmp.addEventListener('loadeddata', resolve);
});
})).then(function() {
alert('Preloading done!');
});

I did a small PONG-game with WebGL and some audio-tags for the sounds. I borrowed the audio-implementation from Opera's Emberwind HTML5 implementation: https://github.com/operasoftware/Emberwind/blob/master/src/Audio.js
Their solution worked fine for me (Chrome, Opera and Firefox). Maybe it could be of interest to you? They have some code that will try to find a playable format from line 22 and below.

Problems preloading audio in Javascript

I'm trying to make a cross-device/browser image and audio preloading scheme for a GameAPI I'm working on. An audio file will preload, and issue a callback once it completes.
The problem is, audio will not start to load on slow page loads, but will usually work on the second try, probably because it cached it and knows it exists.
I've narrowed it down to the audio.load() function. Getting rid of it solves the problem, but interestingly, my motorola droid needs that function.
What are some experiences you've had with HTML5 audio preloading?
Here's my code. Yes, I know loading images in a separate function could cause a race condition :)
var resourcesLoading = 0;
function loadImage(imgSrc) {
//alert("Starting to load an image");
resourcesLoading++;
var image = new Image();
image.src = imgSrc;
image.onload = function() {
//CODE GOES HERE
//alert("A image has been loaded");
resourcesLoading--;
onResourceLoad();
}
}
function loadSound(soundSrc) {
//alert("Starting to load a sound");
resourcesLoading++;
var loaded = false;
//var soundFile = document.createElement("audio");
var soundFile = document.createElement("audio");
console.log(soundFile);
soundFile.autoplay = false;
soundFile.preload = false;
var src = document.createElement("source");
src.src = soundSrc + ".mp3";
soundFile.appendChild(src);
function onLoad() {
loaded = true;
soundFile.removeEventListener("canplaythrough", onLoad, true);
soundFile.removeEventListener("error", onError, true);
//CODE GOES HERE
//alert("A sound has been loaded");
resourcesLoading--;
onResourceLoad();
}
//Attempt to reload the resource 5 times
var retrys = 4;
function onError(e) {
retrys--;
if(retrys > 0) {
soundFile.load();
} else {
loaded = true;
soundFile.removeEventListener("canplaythrough", onLoad, true);
soundFile.removeEventListener("error", onError, true);
alert("A sound has failed to loaded");
resourcesLoading--;
onResourceLoad();
}
}
soundFile.addEventListener("canplaythrough", onLoad, true);
soundFile.addEventListener("error", onError, true);
}
function onResourceLoad() {
if(resourcesLoading == 0)
onLoaded();
}
It's hard to diagnose the problem because it shows no errors and only fails occasionally.

I got it working. The solution was fairly simple actually:
Basically, it works like this:
channel.load();
channel.volume = 0.00000001;
channel.play();
If it isn't obvious, the load function tells browsers and devices that support it to start loading, and then the sound immediately tries to play with the volume virtually at zero. So, if the load function isn't enough, the fact that the sound 'needs' to be played is enough to trigger a load on all the devices I tested.
The load function may actually be redundant now, but based off the inconsistiency with audio implementation, it probably doesn't hurt to have it.
Edit: After testing this on Opera, Safari, Firefox, and Chrome, it looks like setting the volume to 0 will still preload the resource.

canplaythrough fires when enough data has buffered that it probably could play non-stop to the end if you started playing on that event. The HTML Audio element is designed for streaming, so the file may not have completely finished downloading by the time this event fires.
Contrast this to images which only fire their event once they are completely downloaded.
If you navigate away from the page and the audio has not finished completely downloading, the browser probably doesn't cache it at all. However, if it has finished completely downloading, it probably gets cached, which explains the behavior you've seen.
I'd recommend the HTML5 AppCache to make sure the images and audio are certainly cached.

The AppCache, as suggested above, might be your only solution to keep the audio cached from one browser-session to another (that's not what you asked for, right?). but keep in mind the limited amount of space, some browsers offer. Safari for instance allows the user to change this value in the settings but the default is 5MB - hardly enough to save a bunch of songs, especially if other websites that are frequented by your users use AppCache as well. Also IE <10 does not support AppCache.

Alright so I ran into the same problem recently, and my trick was to use a simple ajax request to load the file entirely once (which end into the cache), and then by loading the sound again directly from the cache and use the event binding canplaythrough.
Using Buzz.js as my HTML5 audio library, my code is basically something like that:
var self = this;
$.get(this.file_name+".mp3", function(data) {
self.sound = new buzz.sound(self.file_name, {formats: [ "mp3" ], preload: true});
self.sound.bind("error", function(e) {
console.log("Music Error: " + this.getErrorMessage());
});
self.sound.decreaseVolume(20);
self.sound.bind("canplaythrough",function(){ self.onSoundLoaded(self); });
});