AudioRecord 录制播放PCM音频

AudioRecord 与 MediaRecorder 区别

AudioRecord 基于字节流录制，输出的是pcm数据，未进行压缩，直接保存的pcm文件不能被播放器识别播放。

可以对音频文件进行实时处理，直播类中对录制的声音进行变声编辑。

MediaRecorder 是基于AudioRecord之上，进行了封装，使用简单，由于本身对录制的音频进行压缩，编码，无法对音频进行实时处理编辑。适用于普通的音频录制。

配合MediaPlayer 进行播放。

public AudioRecord(int audioSource, int sampleRateInHz, int channelConfig, int audioFormat,
int bufferSizeInBytes)

AudioRecord 构造函数

AudioSource  音频源， 常用MediaRecorder.AudioSource.MIC(麦克风音频源)

SampleRateInHz  采样率，（采样率用赫兹表示。44100Hz是目前唯一的*保证适用于所有设备的费率）

ChannelConfig  音频声道

AudioFormat  返回音频数据格式

BufferSizeInBytes 缓冲区大小

录制流程：

• 构造AudioRecord 对象
• startRecording() 开始采集
• 在线程中将采集数据写入pcm文件
• stop() 停止采集

  public void record(){
      mAudioRecord.startRecording();
  new Thread(new Runnable() {
      @Override
      public void run() {
              FileOutputStream fileOutputStream=new FileOutputStream(recordFile);
              byte[] buffer=new byte[mBufferSizeInBytes];
              while(isRecording){
                  int read=mAudioRecord.read(buffer,0,mBufferSizeInBytes);
                  if(AudioRecord.ERROR_INVALID_OPERATION!=read){
                      fileOutputStream.write(buffer);
                  }
              }
              fileOutputStream.close();
          }
      }).start();
  
  }
  public void stopRecord(){
      isRecording=false;
      if(mAudioRecord.getState()==AudioRecord.RECORDSTATE_RECORDING){
          mAudioRecord.stop();
       }
       mAudioRecord.release();
  }

  使用AudioTrack播放

  • 构造AudioTrack
  • play() 
  • 在线程中write() 写入pcm文件流
  • release()回收资源

  与MediaPlayer的区别

  MediaPlayer可以播放多种格式的声音文件，例如MP3，AAC，WAV，OGG，MIDI等。MediaPlayer会在framework层创建对应的音频解码器。而AudioTrack只能播放已经解码的PCM流，如果对比支持的文件格式的话则是AudioTrack只支持wav格式的音频文件，因为wav格式的音频文件大部分都是PCM流。AudioTrack不创建解码器，只能播放不需要解码的wav文件

  构造函数

  public AudioTrack(AudioAttributes attributes, AudioFormat format, int bufferSizeInBytes,
  int mode, int sessionId)

  mAudioTrack.play();

  new Thread(new Runnable(){
      @Override
      public void run() {
  
  try {
  FileInputStream fileInputStream=new FileInputStream(filePath);
  byte[] tempBuffer=new byte[mWriteMinBufferSize];
  while (fileInputStream.available()>0){
  int readCount= fileInputStream.read(tempBuffer);
  if (readCount== AudioTrack.ERROR_INVALID_OPERATION||readCount==AudioTrack.ERROR_BAD_VALUE){
  continue;
  }
  if (readCount!=0&&readCount!=-1){
  mAudioTrack.write(tempBuffer,0,readCount);
  }
  }
  Log.e("TAG","end");
  } catch (Exception e) {
  e.printStackTrace();
  }
  
      }
  }).start();

  实例：使用AudioRecord 采集PCM,AudioTrack 播放

  package com.rexkell.mediaapplication;
  
  import android.media.AudioAttributes;
  import android.media.AudioFormat;
  import android.media.AudioManager;
  import android.media.AudioRecord;
  import android.media.AudioTrack;
  import android.media.MediaRecorder;
  import android.os.Bundle;
  import android.support.annotation.Nullable;
  import android.support.v7.app.AppCompatActivity;
  import android.util.Log;
  import android.view.View;
  import android.widget.Button;
  
  import com.rexkell.mediaapplication.media.MediaConfig;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.util.concurrent.Executors;
  
  /**
  * author: rexkell
  * date: 2019/7/22
  * explain:
  */
  public class AudioRecordActivity extends AppCompatActivity {
      boolean isRecording=false;
      //音频源 MIC指的是麦克风
      private final int mAudioSource= MediaRecorder.AudioSource.MIC;
      //（MediaRecoder 的采样率通常是8000Hz AAC的通常是44100Hz。 设置采样率为44100，目前为常用的采样率，官方文档表示这个值可以兼容所有的设置）
      private final int SampleRateInHz=44100; //采样率
      //输入声道
      private final int channelInMono= AudioFormat.CHANNEL_CONFIGURATION_MONO;
      private final int channelOutMono=AudioFormat.CHANNEL_OUT_MONO;
      //指定音频量化位数 ,在AudioFormaat类中指定了以下各种可能的常量。通常我们选择ENCODING_PCM_16BIT和ENCODING_PCM_8BIT PCM代表的是脉冲编码调制，它实际上是原始音频样本。
      //因此可以设置每个样本的分辨率为16位或者8位，16位将占用更多的空间和处理能力,表示的音频也更加接近真实
      private final int mAudioFormat=AudioFormat.ENCODING_PCM_16BIT;
      //指定缓冲区大小
      private int mBufferSizeInBytes;
      private String filePath;
  
      private int mWriteMinBufferSize;
      private AudioAttributes mAudioAttributes;
      AudioRecord mAudioRecord;
      AudioTrack mAudioTrack;
      @Override
      protected void onCreate(@Nullable Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.ac_audio_record);
          filePath=getExternalFilesDir("Music").getPath()+"/test.pcm";
          initAudioRecord();
      }
      private void initAudioRecord(){
        mBufferSizeInBytes=AudioRecord.getMinBufferSize(SampleRateInHz,channelInMono,mAudioFormat);
        mWriteMinBufferSize=AudioTrack.getMinBufferSize(SampleRateInHz,channelInMono,mAudioFormat);
        mAudioRecord=new AudioRecord(mAudioSource,SampleRateInHz,channelInMono,mAudioFormat,mBufferSizeInBytes);
  
        AudioFormat audioFormat=new AudioFormat.Builder().setSampleRate(SampleRateInHz).setEncoding(mAudioFormat).setChannelMask(channelOutMono).build();
        mAudioAttributes=new AudioAttributes.Builder().setUsage(AudioAttributes.USAGE_MEDIA).setContentType(AudioAttributes.CONTENT_TYPE_MUSIC).build();
        mAudioTrack=new AudioTrack(mAudioAttributes,audioFormat,mWriteMinBufferSize, AudioTrack.MODE_STREAM, AudioManager.AUDIO_SESSION_ID_GENERATE);
        File recordFile=new File(filePath);
       if (!recordFile.exists()){
           try {
               recordFile.createNewFile();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
  
      }
      public void record(View view){
          isRecording=!isRecording;
          String text=isRecording?"结束":"录制";
          ((Button)view).setText(text);
          if (isRecording){
              final File recordFile=new File(filePath);
              if (recordFile.exists()){
                  recordFile.delete();
                  try {
                      recordFile.createNewFile();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              mAudioRecord.startRecording();
              Executors.newSingleThreadExecutor().execute(new Runnable() {
                  @Override
                  public void run() {
                      try {
                          FileOutputStream fileOutputStream=new FileOutputStream(recordFile);
                          byte[] buffer=new byte[mBufferSizeInBytes];
                          while (isRecording){
                              int read=mAudioRecord.read(buffer,0,mBufferSizeInBytes);
                              if (AudioRecord.ERROR_INVALID_OPERATION!=read){
                                  fileOutputStream.write(buffer);
                              }
                          }
                          fileOutputStream.close();
                      } catch (Exception e) {
                          e.printStackTrace();
                      }
                  }
              });
          }else {
              if (mAudioRecord!=null&&isRecording){
                  if (mAudioRecord.getState()==AudioRecord.RECORDSTATE_RECORDING){
                      mAudioRecord.stop();
                  }
                  mAudioRecord.release();
                  isRecording=false;
              }
  
          }
  
      }
      public void play(View view){
          mAudioTrack.play();
          Executors.newSingleThreadExecutor().execute(new Runnable() {
              @Override
              public void run() {
                  try {
                      FileInputStream fileInputStream=new FileInputStream(filePath);
                      byte[] tempBuffer=new byte[mWriteMinBufferSize];
                      while (fileInputStream.available()>0){
                         int readCount= fileInputStream.read(tempBuffer);
                         if (readCount== AudioTrack.ERROR_INVALID_OPERATION||readCount==AudioTrack.ERROR_BAD_VALUE){
                             continue;
                         }
                         if (readCount!=0&&readCount!=-1){
                             mAudioTrack.write(tempBuffer,0,readCount);
                         }
                      }
                      Log.e("TAG","end");
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
      }
  
      @Override
      protected void onDestroy() {
         if (mAudioRecord!=null){
             mAudioRecord.release();
             mAudioRecord=null;
         }
         if (mAudioTrack!=null){
             mAudioTrack.release();
             mAudioTrack=null;
         }
         super.onDestroy();
      }
  }