问题
I've been checking Web Audio API documentation and the tutorials but haven't quiet figured out how to approach this problem.
Let's say I load few wav files via XMLHttpRequest and then create buffersources. I know I can schedule when the playback starts precisely. But what if I don't want to play them, but instead want to store and schedule them in a buffer.
A real example: I want to create a simple sequencer where you schedule drums and than export the whole mix to wav (without recording it using RecorderJS or something). Any ideas, libraries?
回答1:
Just did something a bit like this.
Essentially, you'll need to create an offline context:
var offline = new webkitOfflineAudioContext(numChannels, lengthInSamples, sampleRate)
You'll have to recreate all your BufferSources using this new context:
var newBufferSource = offline.createBufferSource();
newBufferSource.buffer = someAudioBuffer;
newBufferSource.connect(offline.destination);
Then schedule your playback:
newBufferSource.start(offline.currentTime + 10);
Then bind to the complete event for your offline rendering:
offline.onComplete = function( ev ){
doSomething(ev.renderedBuffer);
}
Then start 'rendering':
offline.startRendering();
Once you have ev.renderedBuffer, you can do whatever you want with it. In my app, I have a WAV encoder that I ended up writing myself - but you could modify Recorder.js to do the same thing pretty easily.
Just a heads-up: webkitOfflineAudioContext is Chrome-only at the moment. Here's a link if you're interested: OfflineAudioContext
来源：https://stackoverflow.com/questions/16969201/web-audio-api-scheduling-sounds-and-exporting-the-mix