HTML5 MP3 <audio> not loading correctly

Question

Ok, my new website has just gone live, delivered through Google Apps. On a lark, I decided to include a javascript / HTML5 Lunar Lander clone (Martian Lander) which I wrote as an exercise a while back. The game works fine when I open it locally, but when it's delivered through GAE, the sounds don't seem to load on every system. In mobile safari, none of them load. In safari on the desktop, they all load reliably on my computer, but not on some other computers. In Chrome (on the desktop) it seems to work, but in Chrome in iOS, only one sound loads. On the desktop, it always seems to be the same sound which fails to load ( explode1.mp3 ), which is the smallest of the sounds I'm loading. As you can see, if you click that link, the sound downloads fine from the server...

At first the problem seemed to be related to case sensitivity, so I switched the case in the filename, but that fix didn't keep working. This is a problem, as my loading bar is directly tied to how many resources have loaded, so it just sits there waiting for a GET request with no reply... Has anyone experienced anything like this, where a GET receives no reply on a specific resource, but loading the resource directly works fine?

I should say that I'm very new to most of these technologies, so it seems quite likely to me that I just made some novice mistake. Unfortunately, I'm not sure what those novice mistakes would be, seeing as I'm a novice!

Here's the code I use to load the sounds:

function loadSound(soundName) {
    var newElement = document.createElement("audio");
    newElement.addEventListener("canplaythrough", assetLoaded, false);
    document.body.appendChild(newElement);

    var audioType = supportedAudioFormat(newElement);
    if (audioType == "") {
        alert("no audio support");
        return;
    }
    newElement.setAttribute("src", "lander/sounds/" + soundName + "." + audioType);

    console.log("loading sound " + newElement.src + "...");

    return newElement;
}

and...

function assetLoaded() {
    var assetName = this.src;

    numAssetsLoaded++;

    console.log("loaded asset " + numAssetsLoaded + " (" + assetName + ")");

    if (numAssetsLoaded >= numAssetsToLoad) {
        shipSpriteSheet.removeEventListener("load", assetLoaded, false);
        pointImage.removeEventListener("load", assetLoaded, false);

        thrustAudioElement.removeEventListener("canplaythrough", assetLoaded, false);
        explosionAudioElement.removeEventListener("canplaythrough", assetLoaded, false);
        victoryAudioElement.removeEventListener("canplaythrough", assetLoaded, false);
        musicTrackElement.removeEventListener("canplaythrough", assetLoaded, false);

        gameState = GAME_STATE_INIT;
    }
}

If you take a look at the console output, you'll see that all of the sounds begin loading (particularly explode1.mp3) but don't necessarily finish and call assetLoaded ...

UPDATE:
It seems to be the consensus is that I should not be using mp3 (incidentally, I'm already using mp3, AAC, AND ogg, but defaulting to mp3), and also that I should use the Web Audio API. These are both welcome pieces of input, and I will make the necessary changes. However, I still don't have an answer to the original question, which is, "Why does one particular sound not load reliably on desktop while the others load with no problem?" Anybody wanna take a crack at that one? Or is the answer going to be something like, "These things are highly unpredictable, and there's no way to fix it except by switching to a more dependable methodology, like Web Audio API"?

UDATE:
Here's an excerpt from my app.yaml file, which, I gather, helps GAE setup the server.

- url: /(.*\.(mp3|ogg|wav))
  static_files: \1
  upload: (.*\.(mp3|ogg|wav))

Answer 1

Some things to be aware of:

• You shouldn't use MP3 for HTML5 games .
• You will need to dual-encode all your sounds to both AAC (.m4a) and Ogg Vorbis (.ogg) to ensure they can be played everywhere, since there is no one format which can be played everywhere.
• You must ensure your server has the correct MIME types for the audio files. Some browsers will happily play audio if the server says it has the wrong MIME type; others will fail silently. For AAC and Ogg Vorbis the types are audio/mp4 and audio/ogg respectively.
• Most mobile devices can only play one sound at a time, and iOS generally doesn't let you play audio unless it's in a user-initiated input event (such as touchstart ).
• You'll probably want to use the Web Audio API where supported (Chrome and iOS 6+) since playback is more reliable and polyphonic even on iOS - but note iOS still mutes the Web Audio API until a user input event .

Answer 2

This is not a direct answer to your question why sound is not being played, but more like what you should do with your game sound effects.

For game sound effects I suggest you use HTML5 Web Audio API which gives more control over how sounds are played (pitch of the sound effect, less delay in playback, etc):

http://www.html5rocks.com/en/tutorials/webaudio/intro/

• iOS 6+ supports Web Audio https://developer.apple.com/technologies/ios6/

• Web audio is not supported in FF yet, but the support is coming