WebRTC 将音频输入作为麦克风播放

Question

我想将我的音频文件作为麦克风输入（不发送我的现场声音，但我的音频文件）播放给连接到 WebRTC 的用户。谁能告诉我怎么做？

我在 JS 代码中做了以下尝试，比如：

1. base64 音频

<script>
var base64string = "T2dnUwACAAAAAAA..";
var snd = new Audio("data:audio/wav;base64," + base64string);
snd.play();
var Sound = (function () {
var df = document.createDocumentFragment();
return function Sound(src) {
    var snd = new Audio(src);
    df.appendChild(snd); 
    snd.addEventListener('ended', function () {df.removeChild(snd);});
    snd.play();
    return snd;
}
}());

var snd = Sound("data:audio/wav;base64," + base64string);
</script>

2. 音频缓冲区

window.AudioContext = window.AudioContext || window.webkitAudioContext;

var audioContext = new AudioContext();
var isPlaying = false;
var sourceNode = null;
var theBuffer = null;

window.onload = function() {
var request = new XMLHttpRequest();
request.open("GET", "sounds/DEMO_positive_resp.wav", true);
request.responseType = "arraybuffer";
request.onload = function() {
  audioContext.decodeAudioData( request.response, function(buffer) { 
        theBuffer = buffer;
    } );
}
request.send();
}

function togglePlayback() {
        var now = audioContext.currentTime;

        if (isPlaying) {
            //stop playing and return
            sourceNode.stop( now );
            sourceNode = null;
            analyser = null;
            isPlaying = false;
            if (!window.cancelAnimationFrame)
                window.cancelAnimationFrame = window.webkitCancelAnimationFrame;
            //window.cancelAnimationFrame( rafID );
            return "start";
        }

        sourceNode = audioContext.createBufferSource();
        sourceNode.buffer = theBuffer;
        sourceNode.loop = true;

        analyser = audioContext.createAnalyser();
        analyser.fftSize = 2048;
        sourceNode.connect( analyser );
        analyser.connect( audioContext.destination );
        sourceNode.start( now );
        isPlaying = true;
        isLiveInput = true;
        return "stop";
    }

请在这种情况下帮助我。这将是非常可观的。

Answer 1

这是一个可以帮助您使用 chrome 流式传输 mp3 或 wav 的演示：

• https://www.webrtc-experiment.com/RTCMultiConnection/stream-mp3-live.html

这是，它是如何写的：

• http://www.rtcmulticonnection.org/docs/getting-started/#stream-mp3-live

以及演示的源代码：

• https://github.com/muaz-khan/RTCMultiConnection/blob/master/demos/stream-mp3-live.html
• https://github.com/muaz-khan/WebRTC-Experiment/issues/222

在第 3 方 WebRTC 应用程序中使用

window.AudioContext = window.AudioContext || window.webkitAudioContext;

var context = new AudioContext();
var gainNode = context.createGain();
gainNode.connect(context.destination);

// don't play for self
gainNode.gain.value = 0;

document.querySelector('input[type=file]').onchange = function() {
    this.disabled = true;

    var reader = new FileReader();
    reader.onload = (function(e) {
        // Import callback function that provides PCM audio data decoded as an audio buffer
        context.decodeAudioData(e.target.result, function(buffer) {
            // Create the sound source
            var soundSource = context.createBufferSource();

            soundSource.buffer = buffer;
            soundSource.start(0, 0 / 1000);
            soundSource.connect(gainNode);

            var destination = context.createMediaStreamDestination();
            soundSource.connect(destination);

            createPeerConnection(destination.stream);
        });
    });

    reader.readAsArrayBuffer(this.files[0]);
};

function createPeerConnection(mp3Stream) {
    // you need to place 3rd party WebRTC code here
}

---

更新时间：2014 年 8 月 28 日星期四下午 5:55

这是从服务器获取 mp3 的方法：

function HTTP_GET(url, callback) {
    var xhr = new XMLHttpRequest();
    xhr.open('GET', url, true);
    xhr.responseType = 'arraybuffer';
    xhr.send();

    xhr.onload = function(e) {
        if (xhr.status != 200) {
            alert("Unexpected status code " + xhr.status + " for " + url);
            return false;
        }

        callback(xhr.response); // return array-buffer
    };
}

// invoke above "HTTP_GET" method
// to load mp3 as array-buffer

HTTP_GET('http://domain.com/file.mp3', function(array_buffer) {

    // Import callback function that provides PCM audio data decoded as an audio buffer
    context.decodeAudioData(array_buffer, function(buffer) {
        // Create the sound source
        var soundSource = context.createBufferSource();

        soundSource.buffer = buffer;
        soundSource.start(0, 0 / 1000);
        soundSource.connect(gainNode);

        var destination = context.createMediaStreamDestination();
        soundSource.connect(destination);

        createPeerConnection(destination.stream);
    });
});