(function(window){ var WORKER_PATH = 'recorderWorker.js'; var Recorder = function(source, cfg){ var config = cfg || {}; var bufferLen = config.bufferLen || 4096; this.context = source.context; this.node = this.context.createJavaScriptNode(bufferLen, 2, 2); var worker = new Worker(config.workerPath || WORKER_PATH); worker.postMessage({ command: 'init', config: { sampleRate: this.context.sampleRate } }); var recording = false, currCallback; this.node.onaudioprocess = function(e){ if (!recording) return; worker.postMessage({ command: 'record', buffer: [ e.inputBuffer.getChannelData(0), e.inputBuffer.getChannelData(1) ] }); } this.configure = function(cfg){ for (var prop in cfg){ if (cfg.hasOwnProperty(prop)){ config[prop] = cfg[prop]; } } } this.record = function(){ recording = true; } this.stop = function(){ recording = false; } this.clear = function(){ worker.postMessage({ command: 'clear' }); } this.getBuffer = function(cb) { currCallback = cb || config.callback; worker.postMessage({ command: 'getBuffer' }) } this.exportWAV = function(cb, type){ currCallback = cb || config.callback; type = type || config.type || 'audio/wav'; if (!currCallback) throw new Error('Callback not set'); worker.postMessage({ command: 'exportWAV', type: type }); } worker.onmessage = function(e){ var blob = e.data; currCallback(blob); } source.connect(this.node); this.node.connect(this.context.destination); //this should not be necessary }; Recorder.forceDownload = function(blob, filename){ var url = (window.URL || window.webkitURL).createObjectURL(blob); var link = window.document.createElement('a'); link.href = url; link.download = filename || 'output.wav'; var click = document.createEvent("Event"); click.initEvent("click", true, true); link.dispatchEvent(click); } window.Recorder = Recorder; })(window); //ADDITIONAL JS recorderWorker.js 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); /* RIFF identifier */ writeString(view, 0, 'RIFF'); /* file length */ view.setUint32(4, 32 + samples.length * 2, true); /* RIFF type */ writeString(view, 8, 'WAVE'); /* format chunk identifier */ writeString(view, 12, 'fmt '); /* format chunk length */ view.setUint32(16, 16, true); /* sample format (raw) */ view.setUint16(20, 1, true); /* channel count */ view.setUint16(22, 2, true); /* sample rate */ view.setUint32(24, sampleRate, true); /* byte rate (sample rate * block align) */ view.setUint32(28, sampleRate * 4, true); /* block align (channel count * bytes per sample) */ view.setUint16(32, 4, true); /* bits per sample */ view.setUint16(34, 16, true); /* data chunk identifier */ writeString(view, 36, 'data'); /* data chunk length */ view.setUint32(40, samples.length * 2, true); floatTo16BitPCM(view, 44, samples); return view; }

)

Audio