linux上的java声音：如何从TargetDataLine中快速捕获到足以跟上？

我正在使用Java声音API和Java 1.7.当我在Linux上运行我的应用程序时,我很难快速地从TargetDataLine读取以跟上记录的内容(java版“1.7.0_51”,Java(TM)SE运行时环境(版本1.7.0_51-b13),Java HotSpot(TM)64位服务器VM(构建24.51-b03,混合模式),Red Hat Enterprise Linux 5).在我的Windows 7笔记本电脑上运行相同的程序时,我没有这个问题.我有点难过.

为了隔离这个问题,我编写了一个程序,它从TargetDataLine中捕获一段时间(交互式确定)并记录每次在固定字节数的阻塞读取中花费的时间,然后将它们与平均值一起打印出来读取时间,已用时间和捕获的音频时间.

我的测试程序如下：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.Mixer;
import javax.sound.sampled.TargetDataLine;

/**
 * This is a test of mic capture delay for given buffer and fetch settings.
 */
public class MicCaptureDelayTest {

   /**
    * the audio format used for capturing and transmitting
    */
   private static final AudioFormat format =
         new AudioFormat(8000,16,1,true,true);

   /**
    * This is the target data line buffer size to request,in bytes.
    */
   private static final int MIC_BUFFER_SIZE = 1000;

   /**
    * This is the number of bytes to try to fetch from the target data line at a
    * time.
    */
   private static final int MIC_FETCH_SIZE = 480;

   /**
    * Searches for available mixers on the system that have a microphone.
    * @return a list of matching mixers
    */
   private static ListdioSystem.getMixerInfo();
      ListdioSystem.getMixer(mixerInfo);
         DataLine.Info lineInfo = new DataLine.Info(TargetDataLine.class,format);
         boolean isSupported = mixer.isLineSupported(lineInfo);

         if (isSupported) {
            matches.add(mixerInfo);
         }
      }

      return matches;
   }

   /**
    * This is the test recording thread.
    */
   private static class MicFetcher extends Thread {

      /**
       * This is the requested recording state.
       */
      private boolean shouldRecord = false;

      /**
       * This is the current processed recording state of the thread.
       */
      private boolean isRecording = false;

      /**
       * This is the Java audio interface line microphone data is captured from.
       */
      private TargetDataLine lineFromMic;

      /**
       * Runs the test mic capture thread body.
       */
      @Override
      public void run() {

         ListdioSystem.getMixer(matchingMixerInfo.get(0));

         DataLine.Info info = new DataLine.Info(TargetDataLine.class,format);

         try {
            lineFromMic = (TargetDataLine) mixerToUse.getLine(info);
            lineFromMic.open(format,MIC_BUFFER_SIZE);
         } catch (LineUnavailableException e) {
            e.printStackTrace();
            return;
         }

         byte[] transferBuffer = new byte[MIC_FETCH_SIZE];
         List


当我在Linux环境中运行时,大约10秒钟的录音,输出如下：

Starting.

Stopping.
read times (ms): 
54.00  18.10  36.62  36.32  35.99  
18.10  18.25  54.26  18.30  35.56  
18.12  35.51  36.74  17.22  36.70  
35.29  18.33  35.60  18.23  54.72  
19.00  37.99  18.14  18.37  53.91  
18.37  35.34  36.00  18.00  36.00  
18.00  54.71  17.22  18.12  36.18  
36.64  36.08  18.00  54.34  18.26  
18.27  35.44  18.30  54.77  18.33  
18.24  36.51  35.47  36.52  18.35  
17.14  54.96  18.13  36.73  17.21  
54.95  18.28  18.37  36.54  36.72  
35.56  18.37  17.23  54.46  18.36  
35.53  18.08  36.00  36.00  17.99  
54.30  18.06  35.22  18.00  18.00  
53.93  18.32  35.63  36.64  18.16  
35.21  18.30  55.65  18.23  18.35  
35.55  36.32  35.60  18.30  36.33  
36.21  17.22  36.54  18.32  54.96  
17.19  18.36  35.62  36.67  35.25  
18.29  18.37  54.63  18.37  36.54  
18.35  53.91  18.37  17.23  36.70  
36.09  36.01  17.19  18.33  53.91  
18.37  36.56  18.36  35.53  36.58  
18.16  53.84  18.26  36.03  18.08
18.12  54.24  18.08  36.14  36.19
18.12  36.08  18.11  53.80  18.28
18.37  36.55  18.13  53.99  18.00
36.12  35.54  18.28  36.56  17.20
53.96  18.00  18.01  36.67  36.53
36.71  17.19  18.37  54.37  18.02
35.97  18.00  54.00  18.00  18.00
36.00  35.99  36.34  18.37  18.35
53.93  18.13  36.63  18.33  36.33
36.34  18.33  36.55  35.51  36.66
18.29  18.06  54.00  17.99  36.08
18.25  36.64  36.38  18.37  35.55
36.66  18.21  36.73  17.19  54.27
18.13  35.55  18.18  36.31  35.56
18.34  53.90  18.36  18.09  36.15
18.22  53.90  18.32  18.37  53.89
18.19  36.04  17.20  53.94  18.31
18.37  36.55  36.70  36.61  18.35
17.18  53.97  18.32  36.55  19.01
18.99  57.00  18.99  38.01  18.98
38.00  18.99  36.99  36.35  18.37
36.55  36.70  18.04  38.00  19.00
38.00  37.99  18.99  37.99  19.00
37.06  36.43  36.03  18.00  18.00
54.47  18.25  36.70  18.22  18.37
53.55  18.33  35.59  36.59  18.29
35.36  18.37  54.89  18.24  36.44
18.33  18.36  53.52  18.13  36.36
35.57  18.20  35.52  18.20  53.78
18.18  18.16  35.49  36.67  36.54
18.37  36.53  36.67  17.19  36.65
18.29  54.87  17.14  18.24  36.68
35.49  35.61  18.27  18.36  53.77
18.24  35.43  18.35  53.90  18.37
18.24  38.00  38.00  37.99  18.99
19.01  37.98  19.00  57.00  18.99
19.00  38.00  18.99  55.01  18.98
35.99  18.00  18.01  54.98  18.00
37.00  17.99  36.00  36.00  17.99
54.01  18.98  18.00  36.02  18.98
53.16  18.34  35.59  36.20  17.98
36.00  18.00  54.00  17.99  18.00
36.00  35.99  36.01  17.99  18.00
54.00  17.98  35.99  18.00  54.28
Mean read time (ms): 30.210176811594206
Time captured (s): 10.35
Time elapsed (s): 10.466399

在我的Windows环境中类似大约10秒录制的输出如下所示：

Starting.

Stopping.
read times (ms):
44.96  30.13  29.97  29.97  30.04
29.96  29.96  30.00  29.99  30.00
29.92  30.01  30.02  30.01  29.99
29.85  45.12  30.03  29.92  29.96
29.98  30.00  29.98  30.00  0.24
44.73  29.94  30.04  29.96  29.86
29.96  30.05  29.85  30.17  30.02
30.00  29.94  29.99  29.99  30.04
29.97  44.99  29.99  30.08  29.88
30.05  29.95  29.97  29.87  0.15
44.95  29.98  29.91  30.08  29.98
30.00  30.01  29.96  29.94  30.04
30.01  29.96  29.88  30.00  29.95
30.04  44.99  29.99  29.96  30.03
30.00  30.07  29.94  30.01  0.21
44.77  29.95  30.02  30.01  30.00
29.96  29.98  30.00  30.00  29.94
29.99  30.04  29.93  29.99  30.02
29.98  44.99  29.99  29.96  30.01
30.03  29.95  30.00  29.97  0.21
44.81  29.88  30.05  29.99  29.99
30.01  29.97  29.99  29.99  29.98
29.99  30.00  29.97  29.98  29.97
30.01  44.95  29.97  30.03  30.00
30.00  30.00  29.99  29.97  0.21
44.79  29.95  30.00  29.99  29.95
29.98  29.93  30.06  29.94  30.08
29.97  30.00  29.97  29.99  29.98
29.94  45.05  30.04  29.91  30.00
29.99  29.97  30.01  29.98  0.21
44.79  29.94  29.99  29.89  30.06
30.03  29.96  30.04  29.98  29.90
30.04  30.00  29.98  30.00  29.97
30.07  44.96  29.98  29.93  30.07
29.98  29.90  30.00  29.94  0.13
44.97  29.98  29.99  29.94  30.02
30.00  29.93  29.99  30.02  30.01
29.99  29.96  30.02  29.90  29.93
30.01  45.04  30.06  29.99  29.98
29.94  30.04  30.00  29.92  0.20
44.83  29.94  29.99  30.00  30.01
30.02  29.87  30.03  29.94  30.03
29.99  30.00  30.07  29.90  29.95
30.05  44.97  30.01  29.98  29.97
30.01  29.99  30.00  29.97  0.21
44.77  29.96  30.00  30.03  29.91
30.00  30.01  30.03  29.93  29.98
29.99  29.99  29.93  30.04  30.04
30.01  44.92  30.04  29.97  29.91
30.08  29.89  29.97  29.88  0.15
45.01  30.09  29.89  30.01  30.01
29.97  29.95  29.96  30.05  30.04
29.88  30.00  29.99  29.94  30.05
29.98  44.99  30.01  30.00  29.99
29.95  30.00  29.88  30.11  0.21
44.78  30.01  29.96  29.99  29.98
29.98  29.99  30.01  29.91  29.82
30.10  29.99  30.15  29.96  29.93
29.98  45.05  29.97  29.99  30.02
29.96  29.98  29.95  30.04  0.21
44.74  30.02  29.97  29.97  30.03
29.99  29.93  29.94  30.07  29.99
29.99  29.94  30.02  29.97  29.90
30.01  45.12  29.91  30.03  29.95
30.03  29.97  29.87  30.09  0.20
44.79  29.98  29.97  29.99  30.01
30.01  29.97  29.99  29.99  30.01
29.99  29.94  30.01  30.00  29.98
29.98  45.02  29.97  29.91  30.06
29.99  29.96  30.02  29.98
Mean read time (ms): 30.073811959885386
Time captured (s): 10.47
Time elapsed (s): 10.777957116

Linux环境的摘要统计信息,大约30秒的记录：

Mean read time (ms): 30.152922254616133
Time captured (s): 30.87
Time elapsed (s): 31.135111

Windows环境的摘要统计信息,大约30秒记录：

Mean read time (ms): 30.020078674852652
Time captured (s): 30.54
Time elapsed (s): 30.901762071

我注意到,经过的时间和捕获的时间之间的差异随着Linux端记录时间的增加而增加.在Linux方面,单个获取时间看起来也不那么规律.
我已经尝试调整缓冲区和获取大小,但我还没有找到一个允许从线路中快速获取的组合.
什么可能导致取得缓慢？如何确定合理的提取和缓冲区大小,以便具有低延迟但快速提取以及时跟上实时？ Linux上是否存在可能影响此问题或我应该检查的声音配置问题？
谢谢！


最佳答案

private static final int MIC_FETCH_SIZE = 480; // 0.12 seconds of data 

这是一个非常小的缓冲区大小,可靠的性能.在16位单声道时,它仅代表240个声音样本.使它更像16000个样本,或者：

private static final int MIC_FETCH_SIZE = 32000; // 2 seconds of data

注意：Java Sound不保证读取数量,而是返回实际读取的字节数.关键是,允许有机会读取最多2秒的数据(如果可用).
我认为这应解决上述大多数问题.

linux上的java声音：如何从TargetDataLine中快速捕获到足以跟上？

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