如何將音頻數據數組轉換爲wav文件？

Question

我有一個記錄用戶音頻註釋的功能。它使用HTML5和閃回回退。我能夠通過getUserMedia（）從HTML5版本獲取音頻數據，但閃回回退將數據作爲浮點數組提供。

我需要這個數據作爲一個wav文件，我不知道該怎麼做。任何幫助非常感謝！

Answer 1

var recLength = 0, 
recBuffersL = [], 
recBuffersR = [], 
sampleRate; 

this.onmessage = function (e) { 
switch (e.data.command) { 
    case 'init': 
     init(e.data.config); 
     break; 
    case 'record': 
     record(e.data.buffer); 
     break; 
    case 'exportWAV': 
     exportWAV(e.data.type); 
     break; 
    case 'getBuffer': 
     getBuffer(); 
     break; 
    case 'clear': 
     clear(); 
     break; 
} 
}; 

function init(config) { 
sampleRate = config.sampleRate; 
} 

function record(inputBuffer) { 
recBuffersL.push(inputBuffer[0]); 
recBuffersR.push(inputBuffer[1]); 
recLength += inputBuffer[0].length; 
} 

function exportWAV(type) { 
var bufferL = mergeBuffers(recBuffersL, recLength); 
var bufferR = mergeBuffers(recBuffersR, recLength); 
var interleaved = interleave(bufferL, bufferR); 
var dataview = encodeWAV(interleaved); 
var audioBlob = new Blob([dataview], { 
    type: type 
}); 

this.postMessage(audioBlob); 
} 

function getBuffer() { 
var buffers = []; 
buffers.push(mergeBuffers(recBuffersL, recLength)); 
buffers.push(mergeBuffers(recBuffersR, recLength)); 
this.postMessage(buffers); 
} 

function clear() { 
recLength = 0; 
recBuffersL = []; 
recBuffersR = []; 
} 

function mergeBuffers(recBuffers, recLength) { 
var result = new Float32Array(recLength); 
var offset = 0; 
for (var i = 0; i < recBuffers.length; i++) { 
    result.set(recBuffers[i], offset); 
    offset += recBuffers[i].length; 
} 
return result; 
} 

function interleave(inputL, inputR) { 
var length = inputL.length + inputR.length; 
var result = new Float32Array(length); 

var index = 0, 
    inputIndex = 0; 

while (index < length) { 
    result[index++] = inputL[inputIndex]; 
    result[index++] = inputR[inputIndex]; 
    inputIndex++; 
} 
return result; 
} 

function floatTo16BitPCM(output, offset, input) { 
for (var i = 0; i < input.length; i++, offset += 2) { 
    var s = Math.max(-1, Math.min(1, input[i])); 
    output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true); 
} 
} 

function writeString(view, offset, string) { 
for (var i = 0; i < string.length; i++) { 
    view.setUint8(offset + i, string.charCodeAt(i)); 
} 
} 

function encodeWAV(samples) { 
var buffer = new ArrayBuffer(44 + samples.length * 2); 
var view = new DataView(buffer); 

writeString(view, 0, 'RIFF'); 
view.setUint32(4, 32 + samples.length * 2, true); 
writeString(view, 8, 'WAVE'); 
writeString(view, 12, 'fmt '); 
view.setUint32(16, 16, true); 
view.setUint16(20, 1, true); 
view.setUint16(22, 2, true); 
view.setUint32(24, sampleRate, true); 
view.setUint32(28, sampleRate * 4, true); 
view.setUint16(32, 4, true); 
view.setUint16(34, 16, true); 
writeString(view, 36, 'data'); 
view.setUint32(40, samples.length * 2, true); 

floatTo16BitPCM(view, 44, samples); 

return view; 
} 

用法：

var AudioContext = win.webkitAudioContext, 
    recorder, audioContext; 


function recordAudio() { 
    if (!config.stream) { 
     alert('No audio.'); 
     return; 
    } 
    initAudioRecorder(config.audioWorkerPath); 
    audioContext = new AudioContext; 
    var mediaStreamSource = audioContext.createMediaStreamSource(config.stream); 

    mediaStreamSource.connect(audioContext.destination); 
    recorder = new window.Recorder(mediaStreamSource); 

    recorder && recorder.record(); 
} 

function stopAudioRecording() { 
    console.warn('Audio recording stopeed'); 
    recorder && recorder.stop(); 
    recorder && recorder.exportWAV(function (blob) { 
     fileType = 'wav'; 
     setBlob(blob); 
    }); 
    recorder && recorder.clear(); 
} 

var writer; 

function setBlob(blob) { 
    blobURL = blob; 

    var config = { 
     blob: blobURL, 
     type: 'audio/wav', 
     fileName: (Math.random() * 1000 << 1000) + '.' + fileType, 
     size: blobURL.length 
    }; 
    writer = RecordRTCFileWriter(config); 

    var reader = new win.FileReader(); 
    reader.readAsDataURL(blobURL); 
    reader.onload = function (event) { 
     blobURL2 = event.target.result; 
    }; 
} 

return { 
    stopAudio: stopAudioRecording, 
    stopVideo: stopVideoRecording, 
    recordVideo: recordVideo, 
    recordAudio: recordAudio, 
    save: saveToDisk, 
    getBlob: function() { 
     return blobURL2; 
    }, 
    toURL: function() { 
     return writer.toURL(); 
    } 
};