Web Audio Api-無法設置“緩沖”屬性

Question

我得到以下代碼，用於加載然后在Chrome瀏覽器上播放.wav文件：

   var songBuffer = null;
   // Fix up prefixing
   window.AudioContext = window.AudioContext || window.webkitAudioContext;
   var context = new AudioContext();

   function loadSound(url) {
       var request = new XMLHttpRequest();
       request.open('GET', url, true);
       request.responseType = 'arraybuffer';

       // Decode asynchronously
       request.onload = function() {
          context.decodeAudioData(request.response, function(buffer) {
             songBuffer = buffer;
        });
      }
      request.send();
     }

   // Fix up prefixing
   window.AudioContext = window.AudioContext || window.webkitAudioContext;
   var context = new AudioContext();

   function playSound(buffer) {
     var source = context.createBufferSource(); 
     // creates a sound source
     source.buffer = buffer;                
     // tell the source which sound to play
     source.connect(context.destination);       
     // connect the source to the context's destination (the speakers)
     source.start(0);                           
     // play the source now                                          
    }

加載是通過以下方式觸發的： <button onclick="loadSound('audio/sound.wav')">load sound</button>並且在生成事件時文件加載正常。

並通過以下方式處理播放： <button onclick="playSound()">play sound</button> 。

console.log告訴我，但是：

Uncaught TypeError: Failed to set the 'buffer' property on 'AudioBufferSourceNode': The provided value is not of type 'AudioBuffer'.

到底是怎么回事？

Answer 1

您沒有將任何內容傳遞給playSound函數，這意味着該行

source.buffer = buffer;

被解釋為

source.buffer = undefined;

由於您的songBuffer變量位於playSound函數可訪問的范圍內，因此您只需刪除buffer參數，然后執行

source.buffer = songBuffer;

因此，要包裝起來-保持原樣，但編輯playSound函數看起來像這樣：

function playSound() {
 var source = context.createBufferSource(); 
 // creates a sound source
 source.buffer = songBuffer;                
 // tell the source which sound to play
 source.connect(context.destination);       
 // connect the source to the context's destination (the speakers)
 source.start(0);                           
 // play the source now                                          
}