如何在Web Audio API中設置麥克風緩衝區大小以避免1/3秒的延遲（在Java中速度更快）？

Question

此代碼適用於Windows 7中的Firefox。它在揚聲器上播放變形的麥克風。它被javascript代碼轉換爲數字，範圍爲-1到1，音頻幅度每秒多次。它有1/3秒的延遲，但相同的硬件在運行java時速度更快，我的https://sourceforge.net/projects/jsoundcard軟件通過計時統計來調整緩衝區的使用。 OS進程線程優先級提高後，它們都會變得更快，但Java仍然快得多。 Theres沒有理由Firefox或Web Audio API應該有更多的延遲，儘管它已成爲瀏覽器中不能正常工作的標準，但HTML5（這是一個正在開發的標準）正在發生變化。 Web Audio API中是否存在調整麥克風緩衝區大小的地方？

var volume = .7; 
var maxMicrophoneAmplitude = 1; 
var soundFunc = function(ins, outs){ 
    var microphoneAmplitude = ins[0]; 
    var estimatedFramesPerSecond = 44100; 
    var decaySeconds = .1; 
    var decay = 1/(estimatedFramesPerSecond*decaySeconds); 
    maxMicrophoneAmplitude = Math.max(maxMicrophoneAmplitude, microphoneAmplitude)*(1-decay); 
    microphoneAmplitude/maxMicrophoneAmplitude * volume 
    outs[0] = microphoneAmplitude/maxMicrophoneAmplitude * volume; 
}; 
soundFunc.inSize = 1; 
soundFunc.outSize = 1; 
var inputNodes = {}; 
window.onload = function(){ 
    var context = new AudioContext(); 
    if(!navigator.getUserMedia && navigator['mozGetUserMedia']){ 
     navigator.getUserMedia = navigator['mozGetUserMedia']; 
    } 
    if(!navigator.getUserMedia && navigator['webkitGetUserMedia']){ 
     navigator.getUserMedia = navigator['webkitGetUserMedia']; 
    } 
    if(!navigator.getUserMedia && navigator['msGetUserMedia']){ 
     navigator.getUserMedia = navigator['msGetUserMedia']; 
    } 
    var framesPerBuffer = 1024; 
    var scriptNode = context.createScriptProcessor(framesPerBuffer, 1, 1); 
    scriptNode.onaudioprocess = function(audioProcessingEvent){ 
     var inputBuffer = audioProcessingEvent.inputBuffer; 
     var outputBuffer = audioProcessingEvent.outputBuffer; 
     var chansIn = []; 
     var chansOut = []; 
     for(var c=0; c<inputBuffer.numberOfChannels; c++){ 
      chansIn[c] = inputBuffer.getChannelData(c); 
     } 
     for(var c=0; c<outputBuffer.numberOfChannels; c++){ 
      chansOut[c] = outputBuffer.getChannelData(c); 
     } 
     var ins = new Float32Array(inputBuffer.numberOfChannels); 
     var outs = new Float32Array(outputBuffer.numberOfChannels); 
     for(var f=0; f<framesPerBuffer; f++){ 
      for(var c=0; c<inputBuffer.numberOfChannels; c++){ 
       ins[c] = chansIn[c][f]; 
      } 
      soundFunc(ins, outs); 
      for(var c=0; c<outputBuffer.numberOfChannels; c++){ 
       chansOut[c][f] = outs[c]; 
      } 
     }  
    } 
    if(navigator.getUserMedia){ 
     navigator.getUserMedia(
      {'audio':true}, 
      function(stream){ 
       var input = context.createMediaStreamSource(stream); 
       //http://stackoverflow.com/questions/22860468/html5-microphone-capture-stops-after-5-seconds-in-firefox says to save a reference to avoid sound ending after 5 seconds 
       inputNodes.mic = input; 
       input.connect(scriptNode); 
       scriptNode.connect(context.destination); 
       input.start(); 
      }, 
      function(e){ alert('Error capturing audio. e='+e); } 
     ); 
    }else alert('getUserMedia not supported in this browser.'); 
}; 

Answer 1

我相信（@cwilso或許可以糾正我在這，如果我錯了），該API使用以下命令，其中樣本從節點拉到一個模型，而不是推樣本節點的節點它。這意味着您在腳本處理器中設置的緩衝區大小是延遲的來源，而不是麥克風流的輸入緩衝區大小。嘗試設置較低的緩衝區大小。

var framesPerBuffer = 256; 
var scriptNode = context.createScriptProcessor(framesPerBuffer, 1, 1);