IOS WebAudio only works on headphones

Question

I've been running into an issue now for a while where on some ios devices my webaudio system only seems to work with headphones where as other devices (exact same os, model, etc) the audio plays perfectly fine through the speakers or headphones. I've searched for a solution to this but haven't found anything on this exact issue. The only thing I can think of is that maybe it's an audio channel issue or something.

How can I fix this?

Answer 1

@Alastair is correct, the mute toggle switch does mute WebAudio, but it does not mute HTML5 tags. Thanks to his work I managed to find a work around for the web which enables WebAudio to play even when the mute toggle switch is on. I'd post this as a comment on his reply, but I don't have the reputation.

In order to play WebAudio you must also play at least one WebAudio sound source node and one HTML5 tag during a user action. It is fine if these sounds are short bits of silence. I found that this self contained code works without any extra files needed:

EDIT 11/29/19: Removed vestigial typescript typedefs. Thanks @Joep. I also realized the code below is woefully out of date and janky. Just consider it an example. Editing this post prompted me to create an open source solution for this. You can see a demo of it here: https://spencer-evans.com/share/github/unmute/ and check out the repo here: https://github.com/swevans/unmute

/**
 * PLEASE DONT USE THIS AS IT IS, THIS IS JUST EXAMPLE CODE.
 * If you want a drop in solution I have a script on git hub
 * Demo:
 * @see https://spencer-evans.com/share/github/unmute/
 * Github Repo:
 * @see https://github.com/swevans/unmute
 */
var isWebAudioUnlocked = false;
var isHTMLAudioUnlocked = false;

function unlock() {
    if (isWebAudioUnlocked  && isHTMLAudioUnlocked) return;

    // Unlock WebAudio - create short silent buffer and play it
    // This will allow us to play web audio at any time in the app
    var buffer = myContext.createBuffer(1, 1, 22050); // 1/10th of a second of silence
    var source = myContext.createBufferSource();
    source.buffer = buffer;
    source.connect(myContext.destination);
    source.onended = function()
    {
        console.log("WebAudio unlocked!");
        isWebAudioUnlocked = true;
        if (isWebAudioUnlocked && isHTMLAudioUnlocked)
        {
            console.log("WebAudio unlocked and playable w/ mute toggled on!");
            window.removeEventListener("mousedown", unlock);
        }
    };
    source.start();

    // Unlock HTML5 Audio - load a data url of short silence and play it
    // This will allow us to play web audio when the mute toggle is on
    var silenceDataURL = "data:audio/mp3;base64,//MkxAAHiAICWABElBeKPL/RANb2w+yiT1g/gTok//lP/W/l3h8QO/OCdCqCW2Cw//MkxAQHkAIWUAhEmAQXWUOFW2dxPu//9mr60ElY5sseQ+xxesmHKtZr7bsqqX2L//MkxAgFwAYiQAhEAC2hq22d3///9FTV6tA36JdgBJoOGgc+7qvqej5Zu7/7uI9l//MkxBQHAAYi8AhEAO193vt9KGOq+6qcT7hhfN5FTInmwk8RkqKImTM55pRQHQSq//MkxBsGkgoIAABHhTACIJLf99nVI///yuW1uBqWfEu7CgNPWGpUadBmZ////4sL//MkxCMHMAH9iABEmAsKioqKigsLCwtVTEFNRTMuOTkuNVVVVVVVVVVVVVVVVVVV//MkxCkECAUYCAAAAFVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV";
    var tag = document.createElement("audio");
    tag.controls = false;
    tag.preload = "auto";
    tag.loop = false;
    tag.src = silenceDataURL;
    tag.onended = function()
    {
        console.log("HTMLAudio unlocked!");
        isHTMLAudioUnlocked = true;
        if (isWebAudioUnlocked && isHTMLAudioUnlocked)
        {
            console.log("WebAudio unlocked and playable w/ mute toggled on!");
            window.removeEventListener("mousedown", unlock);
        }
    };
    var p = tag.play();
    if (p) p.then(function(){console.log("play success")}, function(reason){console.log("play failed", reason)});
}

window.addEventListener("mousedown", unlock);

Answer 2

If the iPhone mute button is down, meaning that the iPhone is muted, what is played through Web Audio Api will be muted.

Unfortunately there is no way to check if that physical button (located on the left edge towards the top of the iPhone) is on or off through Javascript.

This issue is completely independent from the fact that in iOS Safari the audio has to be started by a user action for it to be unmuted. There are some tricks that can be done to overcome that fact, including the one suggested by here Spencer, were you use "any action or a specific action" started by the user to "play" a silent audio file to allow subsequently playing audio files to play unmuted.