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Web Audio streaming with fetch API
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// | |
// loads remote file using fetch() streams and "pipe" it to webaudio API | |
// remote file must have CORS enabled if on another domain | |
// | |
// mostly from http://stackoverflow.com/questions/20475982/choppy-inaudible-playback-with-chunked-audio-through-web-audio-api | |
// | |
function play(url) { | |
var context = new (window.AudioContext || window.webkitAudioContext)(); | |
var audioStack = []; | |
var nextTime = 0; | |
fetch(url).then(function(response) { | |
var reader = response.body.getReader(); | |
function read() { | |
return reader.read().then(({ value, done })=> { | |
context.decodeAudioData(value.buffer, function(buffer) { | |
audioStack.push(buffer); | |
if (audioStack.length) { | |
scheduleBuffers(); | |
} | |
}, function(err) { | |
console.log("err(decodeAudioData): "+err); | |
}); | |
if (done) { | |
console.log('done'); | |
return; | |
} | |
read() | |
}); | |
} | |
read(); | |
}) | |
function scheduleBuffers() { | |
while ( audioStack.length) { | |
var buffer = audioStack.shift(); | |
var source = context.createBufferSource(); | |
source.buffer = buffer; | |
source.connect(context.destination); | |
if (nextTime == 0) | |
nextTime = context.currentTime + 0.01; /// add 50ms latency to work well across systems - tune this if you like | |
source.start(nextTime); | |
nextTime += source.buffer.duration; // Make the next buffer wait the length of the last buffer before being played | |
}; | |
} | |
} | |
var url = 'http://www.metadecks.org/software/sweep/audio/demos/beats1.wav?adazdaz' | |
play(url); |
I think that decodeAudioData cannot be called without audio header. So the first chunk is decoded, because it has the wav header readed from file, next chunks ( raw pcm in this case ) fails to decode because of the missing header.
I tried your example,I also found that "decodeAudioData" cannot be called without audio header,So your example is problematic.
read()
can be improved:
function read() {
return reader.read().then(({ value, done })=> {
if (done) {
console.log('done');
return;
}else{
console.log(value,done);
context.decodeAudioData(value.buffer, function(buffer) {
audioStack.push(buffer);
if (audioStack.length) {
scheduleBuffers();
}
}, function(err) {
console.log("err(decodeAudioData): "+err);
});
}
read()
});
}
Otherwise I get a undefined error
It works on Chrome but not Firefox. The error on firefox: TypeError: response.body is undefined.
Also, how do we pause this?
I'm getting
Uncaught (in promise) DOMException: Unable to decode audio data
using your code in Chrome console on http://www.metadecks.org/
were you able to solve this?
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I'm getting
Uncaught (in promise) DOMException: Unable to decode audio data
using your code in Chrome console on http://www.metadecks.org/