HTML5 Audio: How to Play only a Selected Portion of an Audio File (audio sprite)?

Question

I'm working on an iOS metronome web app. Since mobile Safari can only play one sound at a time, I'm attempting to create an 'audio sprite' - where I can use different segments of a single audio track to generate different sounds. I have a 1 second clip with 2 half-second sounds on it.

<audio id="sample" src="sounds.mp3"></audio>

<a href="javascript:play1();">Play1</a>
<a href="javascript:play2();">Play2</a>
<a href="javascript:pauseAudio();">Pause</a>

<script>
var audio = document.getElementById('click');

function play1(){
    audio.currentTime = 0;
    audio.play();

    // This is the problem area
    audio.addEventListener('timeupdate', function (){
        if (currentTime >= 0.5) {
            audio.pause();
        }
    }, false);
}   

function play2(){
    audio.currentTime = 0.5;
    audio.play();
}

function pause(){
    audio.pause();
}
</script>

See it on JSFiddle.

As you can see, I've attempted to use the 'timeupdate' event (jPlayer example) with no avail.

I've seen Remy Sharp's post on audio sprites, but (A) I wasn't able to get it to work for me, and (B) I would prefer to stay away from a library dependency.

Any ideas?

---

Update

I now have it working using setInterval:

function play1(){
    audio.currentTime = 0;
    audio.play();
    int = setInterval(function() {
        if (audio.currentTime > 0.4) {
            audio.pause();
            clearInterval(int);
        }
    }, 10);
}    

function play2(){
    clearInterval(int);
    audio.currentTime = 0.5;
    audio.play();
}

There are some issues with sequence and setting/clearing intervals, but for my purpose - it seems to work.

JSFiddle

P.S. If anyone has a fix for this, this could be used in Games and Interface Sound FX.

Answer 1

I think there are a couple of problems here.

Firstly, you're adding an event listener every time the user clicks Play 1.

Also I think

if (currentTime >= 0.5) { ...

should be

if (audio.currentTime >= 0.5) { ...

This also works:

<audio id="sample" src="http://dl.dropbox.com/u/222645/click1sec.mp3" controls preload></audio>

<a href="javascript:playSegment(0.0, 0.5);">Play1</a>
<a href="javascript:playSegment(0.5);">Play2</a>

<script>
var audio = document.getElementById('sample');
var segmentEnd;

audio.addEventListener('timeupdate', function (){
    if (segmentEnd && audio.currentTime >= segmentEnd) {
        audio.pause();
    }   
    console.log(audio.currentTime);
}, false);

function playSegment(startTime, endTime){
    segmentEnd = endTime;
    audio.currentTime = startTime;
    audio.play();
}
</script>

Answer 2

I didn't find a clean function to play segment of an audio object so this is what I come up with. It will also solves the the following error which will occur if the user click multiple triggers within short amount of time.

"Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause()"

const audioObj_1 = new Audio('/some_audio_file.m4a');
playSegment(audioObj_1 , 1.11, 2.45); // this will play from 1.11 sec to 2.45 sec

function playSegment(audioObj, start, stop){
    let audioObjNew = audioObj.cloneNode(true); //this is to prevent "play() request was interrupted" error. 
    audioObjNew.currentTime = start;
    audioObjNew.play();
    audioObjNew.int = setInterval(function() {
        if (audioObjNew.currentTime > stop) {
            audioObjNew.pause();
            clearInterval(audioObjNew.int);
        }
    }, 10);
}