Change sample rate of AudioContext (getUserMedia)

Question

Im trying to record a 48000Hz recording via getUserMedia. But without luck. The returned audio MediaStream returns 44100Hz. How can i set this to 48000Hz?

Here are s

Answer 1

You can use an OfflineAudioContext to essentially render your audio buffer to a different sample rate (but this is batch operation).

So you would record your recording using the normal audio context, and then use an OfflineAudioContext with a different sample rate to render your buffer. There is an example on the Mozilla page.

Answer 2

It is now in the spec but not yet implemented in Chromium. Also in bugs.chromium.org, "Status: Available" does not mean it is implemented. It just means that nobody is working on it and that it is available for anyone who wants to work on it. So "Available" means "Not assigned".

Answer 3

You can't. The sample rate of the AudioContext is set by the browser/device and there is nothing you can do to change it. In fact, you will find that 44.1kHz on your machine might be 48kHz on mine. It varies to whatever the OS picks by default.

Also remember that not all hardware is capable of all sample rates.

Answer 4

As far as I know, there is no way to change the sample rate within an audio context. The sample rate will usually be the sample rate of your recording device and will stay that way. So you will not be able to write something like this:

var input = audio_context.createMediaStreamSource(stream);
var resampler = new Resampler(44100, 48000);
input.connect(resampler);
resampler.connect(audio_context.destination);

However, if you want to take your audio stream, resample it and then send it to the backend (or do sth. else with it outside of the Web Audio API), you can use an external sample rate converter (e.g. https://github.com/taisel/XAudioJS/blob/master/resampler.js).

   var resampler = new Resampler(44100, 48000, 1, 2229);

   function startUsermedia(stream) {
        var input = audio_context.createMediaStreamSource(stream);
        console.log('Media stream created.');


        recorder = audio_context.createScriptProcessor(2048);
        recorder.onaudioprocess = recorderProcess;
        recorder.connect(audio_context.destination);
    }

    function recorderProcess(e) {
        var buffer = e.inputBuffer.getChannelData(0);
        var resampled = resampler.resampler(buffer);
        //--> do sth with the resampled data for instance send to server
    }

Answer 5

audioContext = new AudioContext({sampleRate: 48000})

Simply Set sample rate when created AudioContext object, This worked for me

Answer 6

it's been added to chrome:

var ctx = new (window.AudioContext || window.webkitAudioContext)({ sampleRate:16000});

https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/AudioContext