onaudioprocess not called on ios11

ios safari web-audio-api ios11

12,115

Solution 1

There are two problems. The main one is that Safari on iOS 11 seems to automatically suspend new AudioContext's that aren't created in response to a tap. You can resume() them, but only in response to a tap.

(Update: Chrome mobile also does this, and Chrome desktop will have the same limitation starting in version 70 / December 2018.)

So, you have to either create it before you get the MediaStream, or else get the user to tap again later.

The other issue with your code is that AudioContext is prefixed as webkitAudioContext in Safari.

Here's a working version:

<html>
<body>
<button onclick="beginAudioCapture()">Begin Audio Capture</button>
<script>
  function beginAudioCapture() {

    var AudioContext = window.AudioContext || window.webkitAudioContext;    
    var context = new AudioContext();
    var processor = context.createScriptProcessor(1024, 1, 1);
    processor.connect(context.destination);

    var handleSuccess = function (stream) {
      var input = context.createMediaStreamSource(stream);
      input.connect(processor);

      var recievedAudio = false;
      processor.onaudioprocess = function (e) {
        // This will be called multiple times per second.
        // The audio data will be in e.inputBuffer
        if (!recievedAudio) {
          recievedAudio = true;
          console.log('got audio', e);
        }
      };
    };

    navigator.mediaDevices.getUserMedia({audio: true, video: false})
      .then(handleSuccess);
  }
</script>
</body>
</html>

(You can set the onaudioprocess callback sooner, but then you get empty buffers until the user approves of microphone access.)

Oh, and one other iOS bug to watch out for: the Safari on iPod touch (as of iOS 12.1.1) reports that it does not have a microphone (it does). So, getUserMedia will incorrectly reject with an Error: Invalid constraint if you ask for audio there.

FYI: I maintain the microphone-stream package on npm that does this for you and provides the audio in a Node.js-style ReadableStream. It includes this fix, if you or anyone else would prefer to use that over the raw code.

Solution 2

Tried it on iOS 11.0.1, and unfortunately this problem still isn't fixed.

As a workaround, I wonder if it makes sense to replace the ScriptProcessor with a function that takes the steam data from a buffet and then processes it every x milliseconds. But that's a big change to the functionality.

Solution 3

Just wondering... do you have the setting enabled in Safari settings? It comes enabled by default in iOS11, but maybe you just disabled it without noticing.

12,115

Author by

John Farrelly

Updated on June 06, 2022

Comments

John Farrelly about 2 years

I am trying to get audio capture from the microphone working on Safari on iOS11 after support was recently added

However, the onaudioprocess callback is never called. Here's an example page:

<html>
    <body>
        <button onclick="doIt()">DoIt</button>
        <ul id="logMessages">
        </ul>
        <script>
            function debug(msg) {
                if (typeof msg !== 'undefined') {
                    var logList = document.getElementById('logMessages');
                    var newLogItem = document.createElement('li');
                    if (typeof  msg === 'function') {
                        msg = Function.prototype.toString(msg);
                    } else if (typeof  msg !== 'string') {
                        msg = JSON.stringify(msg);
                    }
                    var newLogText = document.createTextNode(msg);
                    newLogItem.appendChild(newLogText);
                    logList.appendChild(newLogItem);
                }
            }
            function doIt() {
                var handleSuccess = function (stream) {
                    var context = new AudioContext();
                    var input = context.createMediaStreamSource(stream)
                    var processor = context.createScriptProcessor(1024, 1, 1);

                    input.connect(processor);
                    processor.connect(context.destination);

                    processor.onaudioprocess = function (e) {
                        // Do something with the data, i.e Convert this to WAV
                        debug(e.inputBuffer);
                    };
                };

                navigator.mediaDevices.getUserMedia({audio: true, video: false})
                        .then(handleSuccess);
            }
        </script>
    </body>
</html>

On most platforms, you will see items being added to the messages list as the onaudioprocess callback is called. However, on iOS, this callback is never called.

Is there something else that I should do to try and get it called on iOS 11 with Safari?

John Farrelly over 6 years

Thanks for the tip @damianmr, but alas camera and microphone access is enabled in Safari, and it will prompt me to allow access the first time I visit the page. it seems everything is working as it should, just the onaudioprocess is never called
John Farrelly over 6 years

Yeah I just tried on iOS 11.0.1 myself. I've seen some demos that do what you suggest, but the "buffer" being sent every X milliseconds is always empty (at least in the demos that I've tried). It seems that access to the microphone bytes themselves is the issue.
Daniel Wu over 6 years

What you wrote gave me a few ideas, unfortunately none of them worked so far. I'll still put them here, maybe it helps. You mentioned the buffet being empty, so my thought was the problem might be with getUserMedia. Tried {audio: true, video: true}, and navigator.getUserMedia instead of navigator.mediaDevices.getUserMedia. none of these combinations worked. Also tried to specify the device ID, that also didn't help.
John Farrelly over 6 years

Hi Nathan - I use Promises in my onclick method - I wonder is this confusing Safari that we're no longer in a user tap action? I've tried a few different things in my actual code, and the AudioContext is always in a suspended state
Daniel Wu over 6 years

Unfortunately I can't comment onto Nathan's answer, but his method works. Moving processor = createScriptProcessor and processor.connect before createMediaStremSource does the trick.
Nathan Friedly over 6 years

Yep, a promise resolution is considered a separate event, and it doesn't count as a direct user action, so audio is blocked. Create an audio context in direct response to the tap, and then use it later.
Nathan Friedly over 6 years

(The whole mess is because Apple doesn't want auto-playing audio on mobile Safari. So they break everything to prevent that.)
John Farrelly over 6 years

Bah! Sorry @nathan-friedly - SO automatically assigned the bounty to a different answer before I had a chance to test this and accept it as the answer.
asiop over 6 years

even as a response to a user action I got the audioContext in suspended state and had to add audioContext.resume() right after its creation, that's 11.0.3
Ko Ohhashi over 6 years

Hi, thank you for great resource. I have a question. How can we convert raw data to blob which we can replay? Thanks in advance.
Nathan Friedly over 6 years

@KoOhhashi check out developer.mozilla.org/en-US/docs/Web/API/MediaRecorder and/or github.com/mattdiamond/Recorderjs
asiop over 6 years

@NathanFriedly I didn't instantiate the processor as a direct response to user action, maybe that's maybe why I had to use audioContext.resume
Nathan Friedly over 6 years

@asiop yep, that would do it.
Kerry Davis over 6 years

a bigger problem for me is that getUserMedia lets you set a sample rate in the audio constraints. However, if the AudioContext is created prior to the getUserMedia the question becomes if this is possible and does it make the sample rate audio constraint a mute point?
Nathan Friedly over 6 years

That's a good question, I don't know if it's possible to control the sample rate of the AudioContext, but that would be convenient. Currently, I just take whatever sample rate I get by default (usually 48 or 44.1khz) and downsample it myself - github.com/watson-developer-cloud/speech-javascript-sdk/blob‌/…
velochy over 5 years

@DanielWu your last comment just fixed my webapp that makes essential use of recording, so I could not be more grateful. Could you maybe edit your answer with it so it would be easier to find for others, as it is glossed over by the others, and somehow seems to make all the difference on iOS Safari.