H5采集pcm流转换采样率实时发送到服务端

     function startTalk(ws2, button) {
         var arrBuffer = new ArrayBuffer(320 * 2);
         var sendBuffer = new DataView(arrBuffer);
         var sendBufferindex  = 0;
         if (navigator.getUserMedia) {
             navigator.getUserMedia(
                 { audio: true },
                 function (stream) {
                     button.text("挂 断")
                     button.attr("status","doing")
                     var context = new AudioContext();
                     var audioInput = context.createMediaStreamSource(stream);
                     var recorder = context.createScriptProcessor(1024, 1, 1);
                     audioInput.connect(recorder);
                     recorder.connect(context.destination);
                     recorder.onaudioprocess = function (e) {
                         var buffer = e.inputBuffer.getChannelData(0);
                         var arrayBuffer = context.createBuffer(1, 1024, context.sampleRate);
                         var nowBuffering = arrayBuffer.getChannelData(0);
                         for (var i = 0; i < arrayBuffer.length; i++) {
                             nowBuffering[i] = buffer[i]
                         }
                         var offctx = new OfflineAudioContext(1, parseInt(1024*16000/context.sampleRate), 16000);
                         var source = offctx.createBufferSource();
                         source.buffer = arrayBuffer;
                         source.connect(offctx.destination);
                         source.start();
                         offctx.startRendering().then(function(renderedBuffer) {
                             var channetData = renderedBuffer.getChannelData(0)
                             source.stop();
                             var index = 0
                             var length = channetData.length
                             while (index < length) {
                                 var selectBuffer = channetData[index]
                                 var s = Math.max(-1, Math.min(1, selectBuffer));
                                 var point = s < 0 ? s * 0x8000 : s * 0x7FFF;
                                 if (sendBufferindex < 320 * 2) {
                                     sendBuffer.setInt16(sendBufferindex, point, true);
                                 } else {
                                     var sendData = {
                                         "cmd":"pcm",
                                         "data":{
                                             "buffer": Array.from(new Int16Array(arrBuffer)),
                                             "timestamp": new Date().getTime(),
                                         }
                                     }
                                     if(ws2.readyState == ws2.CLOSING || ws2.readyState == ws2.CLOSED) {
                                         recorder.disconnect()
                                         return
                                     }
                                     ws2.send(JSON.stringify(sendData))

                                     sendBuffer = new DataView(arrBuffer);
                                     sendBufferindex = 0;
                                     sendBuffer.setInt16(sendBufferindex, point, true);
                                 }
                                 index++;
                                 sendBufferindex = sendBufferindex + 2;
                             }
                         })

                     }
                 },
                 function() {
                     ws2.close()
                     button.attr("status","close")
                     button.text("通 话")
                     alert('请插入耳机');