android - 麦克风输入的处理

Question

我正在尝试从麦克风获取音频数据。我通过使用 AudioRecord 类实现了这一点，该类填充了类型为 shorts 的缓冲区。

最后，我想绘制此缓冲区的图形，以便获得类似显示(实时信息)的示波器。问题是，如果我想显示一个值(比如文本)，那么我需要一个不同的线程来更新 UI。目前，我通过使用 AsyncTask 并使用 AsyncTasks.publishProgress() 更新 UI 来执行此操作。到目前为止，我还不是很成功，想知道我是否在正确的轨道上？ handle 是更好的方法吗？有没有人以前做过类似的事情，如果有的话，哪种方法对你有用？另外，是否可以简单地轮询麦克风？

---

这是我的代码。它旨在输出来自 MIC 的每个读取样本。它似乎以可接受的速度执行此操作，但偶尔会显示零。为什么？

package com.ss.audioacquireapp3;

import android.app.Activity;
import android.content.Context;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;


public class AudioAcquireApp3Activity extends Activity 
{
        //Properties (AsyncTask)
        protected TextView _percentField;
        protected InitTask _initTask;

        //Properties (MIC)
        public AudioRecord audioRecord; 
        public int mSamplesRead; //how many samples read 
        public int recordingState;
        public int buffersizebytes; 
        public int channelConfiguration = AudioFormat.CHANNEL_IN_MONO; 
        public int audioEncoding = AudioFormat.ENCODING_PCM_16BIT; 
        public static short[] buffer; //+-32767 
        public static final int SAMPPERSEC = 44100; //samp per sec 8000, 11025, 22050 44100 or 48000

    @Override
    public void onCreate( Bundle savedInstanceState ) 
    {
        super.onCreate(savedInstanceState);
        setContentView( R.layout.main );

        _percentField = ( TextView ) findViewById( R.id.percent_field );

        buffersizebytes = AudioRecord.getMinBufferSize(SAMPPERSEC,channelConfiguration,audioEncoding); //4096 on ion 
        buffer = new short[buffersizebytes]; 
        audioRecord = new AudioRecord(android.media.MediaRecorder.AudioSource.MIC,SAMPPERSEC,channelConfiguration,audioEncoding,buffersizebytes); //constructor 

        _initTask = new InitTask();
        _initTask.execute( this );
    }

    /**
     * sub-class of AsyncTask
     */
    protected class InitTask extends AsyncTask<Context, Integer, String>
    {
        // -- run intensive processes here
        // -- notice that the datatype of the first param in the class definition matches the param passed to this method 
        // -- and that the datatype of the last param in the class definition matches the return type of this method
                @Override
                protected String doInBackground( Context... params ) 
                {
                        //-- on every iteration
                        //-- runs a while loop that causes the thread to sleep for 50 milliseconds 
                        //-- publishes the progress - calls the onProgressUpdate handler defined below
                        //-- and increments the counter variable i by one
                        //int i = 0;

                    audioRecord.startRecording();

                        while( true ) 
                        {
                                try{
                                        mSamplesRead = audioRecord.read(buffer, 0, buffersizebytes);

                                        int amp;

                                        for(int i = 0; i < buffersizebytes - 1; i++){
                                            amp = (int)buffer[i];
                                            publishProgress( amp );
                                        }

                                } catch( Exception e ){                        
                                }
                        }
                }

                // -- gets called just before thread begins
                @Override
                protected void onPreExecute() 
                {
                        //Log.i( "makemachine", "onPreExecute()" );
                        super.onPreExecute();

                }

                // -- called from the publish progress 
                // -- notice that the datatype of the second param gets passed to this method
                @Override
                protected void onProgressUpdate(Integer... values) 
                {
                        super.onProgressUpdate(values);
                        //Log.i( "makemachine", "onProgressUpdate(): " +  String.valueOf( values[0] ) );
                        _percentField.setText( String.valueOf(values[0]) );
                }

                // -- called as soon as doInBackground method completes
                // -- notice that the third param gets passed to this method
                @Override
                protected void onPostExecute( String result ) 
                {
                        super.onPostExecute(result);
                        //Log.i( "makemachine", "onPostExecute(): " + result );
                }   


     } 
}

这是main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_vertical|center_horizontal"
    >

<TextView android:id="@+id/percent_field"
          android:layout_width="fill_parent" 
          android:layout_height="wrap_content"
          android:gravity="center_horizontal"/>

</LinearLayout>

注意你需要把这个添加到AndroidManifest.xml

<uses-permission android:name="android.permission.RECORD_AUDIO" />

我在 LG Optimus Black 上运行它。请帮助我使这段代码尽可能高效。

Answer 1

1. 如果您需要从任何线程更新 UI 线程，您可以始终使用 Activity.runOnUiThread(Runnable action)。有关详细信息，请参阅 Activity 类 javadoc。
2. 我不确定您所说的“简单轮询麦克风”到底是什么意思，但我认为 AudioRecord 是录制麦克风的好方法。这是示例实现的链接，它实时读取录制音频的频率:http://www.anddev.org/novice-tutorials-f8/get-frequency-data-from-microphone-in-real-time-t16774.html

希望这对您有所帮助。