如何通过AudioTrack播放大型PCM文件？ （目前出现错误）

Question

我一直在为我制作的应用程序编写一些代码，并且需要播放大型PCM文件（600mb以上）。

这是我的打法当前代码（）方法：

public void play(View view) { 
     Toast.makeText(this, "play", Toast.LENGTH_SHORT).show(); 

// Get the file we want to playback. 
     File file = new File(Environment.getExternalStorageDirectory() + File.separator + "ACS.pcm"); 
// Get the length of the audio stored in the file (16 bit so 2 bytes per short) 
// and create a short array to store the recorded audio. 
     int musicLength = (int)(file.length()/2); 
     short[] music = new short[musicLength]; 


     try { 
// Create a DataInputStream to read the audio data back from the saved file. 
      InputStream is = new FileInputStream(file); 
      BufferedInputStream bis = new BufferedInputStream(is); 
      DataInputStream dis = new DataInputStream(bis); 

// Read the file into the music array. 
      int i = 0; 
      while (dis.available() > 0) { 
       music[musicLength-1-i] = dis.readShort(); 
       i++; 
      } 


// Close the input streams. 
      dis.close(); 


// Create a new AudioTrack object using the same parameters as the AudioRecord 
// object used to create the file. 
      AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 
        44100, 
        AudioFormat.CHANNEL_OUT_MONO, 
        AudioFormat.ENCODING_PCM_16BIT, 
        musicLength, 
        AudioTrack.MODE_STREAM); 
// Start playback 
      audioTrack.play(); 

// Write the music buffer to the AudioTrack object 
      audioTrack.write(music, 0, musicLength); 


     } catch (Throwable t) { 
      Log.e("AudioTrack","Playback Failed"); 
     } 
    } 

然而上线的应用程序崩溃：short[] music = new short[musicLength]; 我相信这是因为应用程序试图创建一个非常大的一个数组大小，因此占用了大量的内存（ram）。

从崩溃的logcat的是：

`11-03 16:31:03.654 16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc sticky concurrent mark sweep GC freed 6307(421KB) AllocSpace objects, 1(12KB) LOS objects, 33% free, 15MB/23MB, paused 678us total 14.444ms 
11-03 16:31:03.663 16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc partial concurrent mark sweep GC freed 213(22KB) AllocSpace objects, 0(0B) LOS objects, 40% free, 15MB/26MB, paused 659us total 7.132ms 
11-03 16:31:03.679 16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc concurrent mark sweep GC freed 15(12KB) AllocSpace objects, 0(0B) LOS objects, 40% free, 15MB/26MB, paused 830us total 14.191ms 
11-03 16:31:03.681 16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Forcing collection of SoftReferences for 641MB allocation 
11-03 16:31:03.695 16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc concurrent mark sweep GC freed 11(344B) AllocSpace objects, 0(0B) LOS objects, 39% free, 15MB/26MB, paused 645us total 13.989ms 
11-03 16:31:03.700 16916-16916/com.bacon.corey.audiotimeshift E/art﹕ Throwing OutOfMemoryError "Failed to allocate a 672164876 byte allocation with 11094652 free bytes and 176MB until OOM" 
11-03 16:31:03.703 16916-16916/com.bacon.corey.audiotimeshift D/AndroidRuntime﹕ Shutting down VM 
11-03 16:31:03.713 16916-16916/com.bacon.corey.audiotimeshift E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    Process: com.bacon.corey.audiotimeshift, PID: 16916 
    java.lang.IllegalStateException: Could not execute method of the activity 
      at android.view.View$1.onClick(View.java:4007) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.reflect.InvocationTargetException 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at android.view.View$1.onClick(View.java:4002) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
    Caused by: java.lang.OutOfMemoryError: Failed to allocate a 672164876 byte allocation with 11094652 free bytes and 176MB until OOM 
      at com.bacon.corey.audiotimeshift.MainActivity.play(MainActivity.java:87) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at android.view.View$1.onClick(View.java:4002) 
      at android.view.View.performClick(View.java:4756) 
      at android.view.View$PerformClick.run(View.java:19749) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:135) 
      at android.app.ActivityThread.main(ActivityThread.java:5221) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:372) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)` 

我已搜查谷歌，但我似乎无法找到打不先加载它的PCM文件转换成短阵的任何方式。 如果有人知道解决方法，并不介意分享，我会非常感激。

感谢 科瑞

Answer 1

的问题是，你想读一个600多MB的文件到内存中一气呵成，和你的应用程序无法获得足够的内存来做到这一点。

你需要做的是创建一个更小的缓冲区，并以块读取音频文件，将每个块写入AudioTrack ...循环中。

（注：我只是从什么AudoioTrackjavadoc说要去你会为自己做的更好的阅读吧...）