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();
    }
}

AudioRecord 录制播放PCM音频

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