Bug 132852 – WebAudio doesn't play sound following User Interaction on iOS+Safari

• Component: Web Audio
• Status: RESOLVED INVALID

[Hugo]

Hi team,

I have implemented the WebAudio for Webkit, and could successfully run it on Android+Chrome, but can not run it on iPad/iPhone with Chrome and Safari 

I trigger the javascript code upon a user interaction (touch on the screen). The function does
1- creates the audio context (only once) 
  if (window.webkitAudioContext) {
    myaudioContext = new webkitAudioContext();
  } else if (window.AudioContext) {
    myaudioContext = new AudioContext();
  }

2- on the same call, loads the sound sounds (only once, using a BufferLoader class (XHR, base64 MP3 files from local URL) onto an array called letters. 

3- The function sets a repeatable timer (3 seconds) and returns from the function.   

4- In parallel, the timer selects the song from the pre-loaded songs list and play the song using 
  var source = myaudioContext.createBufferSource();
  source.buffer = songs[random].buffer;
  source.connect(myaudioContext.destination);

  if (!source.start) source.start = source.noteOn;
  source.start(0);

I tried adding the code below (thanks Jer) 
  try{
    myaudioContext.startRendering();
  }catch (ex){};
but it did not help 

The code executes just fine, but no sound comes out of the speaker. 

The use case is fairly trivial. This works on all windows browsers (FF, Safari, Chrome), on Mac browsers (Chrome, Safari and Firefox) and mobile tablets with Chrome on Nexus/Android OS. => But it doesn't work on Safari and Chrome on iOS (iPad and iPhone).

The parsing of the MP3 files work just fine, in fact, I can create an <audio> element in the HTML, and when I click on it, play the song just fine, so I believe the MP3 is encoded properly, and decoded by the context just fine.

I am puzzled by this problem.  

Thank you for taking the time to help me. I'm attaching the test case here. 

Thank you for your support. 

Best regards

Hugo

PS: Sorry it took me a bit to log this case, so this might seem redundant with https://bugs.webkit.org/show_bug.cgi?id=132691

[Hugo]

Created attachment 231358 [details]
Here is the test case for https://bugs.webkit.org/attachment.cgi?bugid=132852

Here is the test case for https://bugs.webkit.org/attachment.cgi?bugid=132852

[Jer Noble]

Try calling `myaudioContext.startRendering();`from within initAudioContext().

initAudioContext() is called in response to a user interaction, whereas playSong() is called in response to a timer.

[Hugo]

That did it. I'm not sure why I couldn't make it work in the first place. Thank you for your great help 

Best

Hugo