Android音视频开发—AudioRecord实现录音功能
AudioRecord实现录音功能
-
- 简介
- 实现步骤及解析
- 测试
简介
AudioRecord类管理Java应用程序的音频资源，以便从平台的音频输入硬件录制音频。
AudioRecord录制的是PCM格式的音频文件，需要用AudioTrack来播放(下一期介绍)，AudioTrack比MediaRecorder更接近底层、更专业。
实现步骤及解析
1、添加权限
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
分别是录音权限；读、写外部存储器权限
2、编写基于AudioRecord的录音工具类
AudioRecordTool.java
package com.audioandvideo.two.Tool;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Environment;
import android.util.Log;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
/**
* 基于AudioRecord的录音工具类
*/
public class AudioRecordTool{
private AudioRecord audioRecord;
private int recordBufSize = 0;
private byte data[];
private PcmToWavTool tool;
private boolean isRecording = false;
//录音得到的文件 的储存位置及文件名
private final String pcmFileName = Environment.getExternalStorageDirectory() + "/Download/record.pcm";
//转换成wav文件后新文件的存储位置及文件名
private final String wavFileName = Environment.getExternalStorageDirectory() + "/Download/record1.wav";
// 音频源：音频输入-麦克风
private final static int AUDIO_INPUT = MediaRecorder.AudioSource.MIC;
// 采样率：音频的采样频率，每秒钟能够采样的次数，采样率越高，音质越高
// 44100是目前的标准，但是某些设备仍然支持22050，16000，11025
// 采样频率一般共分为22.05KHz、44.1KHz、48KHz三个等级
private final static int AUDIO_SAMPLE_RATE = 44100;
// 声道设置：android支持双声道立体声和单声道。MONO单声道，STEREO立体声
private final static int AUDIO_CHANNEL = AudioFormat.CHANNEL_IN_MONO;
// 编码制式和采样大小：采集来的数据当然使用PCM编码
// (脉冲代码调制编码，即PCM编码。PCM通过抽样、量化、编码三个步骤将连续变化的模拟信号转换为数字编码。)
// android支持的采样大小16bit 或者8bit。当然采样大小越大，那么信息量越多，音质也越高，现在主流的采样
// 大小都是16bit，在低质量的语音传输的时候8bit 足够了。
private final static int AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
//初始化
public void createAudioRecord() {
recordBufSize = AudioRecord.getMinBufferSize(AUDIO_SAMPLE_RATE, AUDIO_CHANNEL, AUDIO_ENCODING); //audioRecord能接受的最小的buffer大小
//构造方法，传入的参数上面在有解析
audioRecord = new AudioRecord(AUDIO_INPUT, AUDIO_SAMPLE_RATE, AUDIO_CHANNEL, AUDIO_ENCODING, recordBufSize);
data = new byte[recordBufSize];
tool = new PcmToWavTool(AUDIO_SAMPLE_RATE,AUDIO_CHANNEL,AUDIO_ENCODING);
}
//开始录音
public void start(){
Log.i("AUDIO","开始录音");
isRecording = true;
//调用startRecording()方法开始录制
audioRecord.startRecording();
MyThread myThread = new MyThread();
myThread.start();
}
//停止录音
public void stop(){
isRecording = false;
if (audioRecord != null){
Log.i("AUDIO","停止录音");
//调用stop()方法停止录制
audioRecord.stop();
//调用release() 释放本机录音资源。
audioRecord.release();
audioRecord = null;
}
//利用自定义工具类将pcm格式的文件转换为wav格式文件才能进行播放
tool.pcmToWav(pcmFileName,wavFileName);
}
private class MyThread extends Thread{
@Override
public void run() {
super.run();
FileOutputStream os = null;
try {
//如果文件不存在，就创建文件
if(!new File(pcmFileName).exists()){
new File(pcmFileName).createNewFile();
}
os = new FileOutputStream(pcmFileName);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
if (null != os) {
while (isRecording) {
//调用read(@NonNull byte[] audioData, int offsetInBytes, int sizeInBytes)方法
// 从音频硬件读取音频数据，以便记录到字节数组中。
int read = audioRecord.read(data, 0, recordBufSize);
// 如果读取音频数据没有出现错误，就将数据写入到文件
if (AudioRecord.ERROR_INVALID_OPERATION != read) {
try {
os.write(data);
} catch (IOException e) {
e.printStackTrace();
}
}
}
try {
//关闭文件
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
3、编写pcm格式转化为wav格式的工具类，播放器才能进行播放
PcmToWavTool .java
package com.audioandvideo.two.Tool;
import android.media.AudioFormat;
import android.media.AudioRecord;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
/**pcm格式转化为wav格式的工具类
* PCM编码是直接存储声波采样被量化后所产生的非压缩数据，故被视为单纯的无损耗编码格式，其优点是可获得高质量的音频信号
* WAV是最常见的声音文件格式之一
*/
public class PcmToWavTool {
/**
* 缓存的音频大小
*/
private int mBufferSize;
/**
* 采样率
*/
private int mSampleRate;
/**
* 声道数
*/
private int mChannel;
/**
* @param sampleRate sample rate、采样率
* @param channel channel、声道
* @param encoding Audio data format、音频格式
*/
PcmToWavTool(int sampleRate, int channel, int encoding) {
this.mSampleRate = sampleRate;
this.mChannel = channel;
this.mBufferSize = AudioRecord.getMinBufferSize(mSampleRate, mChannel, encoding);
}
/**
* pcm文件转wav文件
*
* @param inFilename 源文件路径
* @param outFilename 目标文件路径
*/
public void pcmToWav(String inFilename, String outFilename) {
FileInputStream in;
FileOutputStream out;
long totalAudioLen;
long totalDataLen;
long longSampleRate = mSampleRate;
int channels = mChannel == AudioFormat.CHANNEL_IN_MONO ? 1 : 2;
long byteRate = 16 * mSampleRate * channels / 8;
byte[] data = new byte[mBufferSize];
try {
in = new FileInputStream(inFilename);
out = new FileOutputStream(outFilename);
totalAudioLen = in.getChannel().size();
totalDataLen = totalAudioLen + 36;
writeWaveFileHeader(out, totalAudioLen, totalDataLen,
longSampleRate, channels, byteRate);
while (in.read(data) != -1) {
out.write(data);
}
in.close();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 加入wav文件头
*/
private void writeWaveFileHeader(FileOutputStream out, long totalAudioLen,
long totalDataLen, long longSampleRate, int channels, long byteRate)
throws IOException {
byte[] header = new byte[44];
// RIFF/WAVE header
header[0] = 'R';
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte) (totalDataLen & 0xff);
header[5] = (byte) ((totalDataLen >> 8) & 0xff);
header[6] = (byte) ((totalDataLen >> 16) & 0xff);
header[7] = (byte) ((totalDataLen >> 24) & 0xff);
//WAVE
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
// 'fmt ' chunk
header[12] = 'f';
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
// 4 bytes: size of 'fmt ' chunk
header[16] = 16;
header[17] = 0;
header[18] = 0;
header[19] = 0;
// format = 1
header[20] = 1;
header[21] = 0;
header[22] = (byte) channels;
header[23] = 0;
header[24] = (byte) (longSampleRate & 0xff);
header[25] = (byte) ((longSampleRate >> 8) & 0xff);
header[26] = (byte) ((longSampleRate >> 16) & 0xff);
header[27] = (byte) ((longSampleRate >> 24) & 0xff);
header[28] = (byte) (byteRate & 0xff);
header[29] = (byte) ((byteRate >> 8) & 0xff);
header[30] = (byte) ((byteRate >> 16) & 0xff);
header[31] = (byte) ((byteRate >> 24) & 0xff);
// block align
header[32] = (byte) (2 * 16 / 8);
header[33] = 0;
// bits per sample
header[34] = 16;
header[35] = 0;
//data
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte) (totalAudioLen & 0xff);
header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
out.write(header, 0, 44);
}
}
4、编写Activity
AudioRecordActivity.java
package com.audioandvideo.two.Activity;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import com.audioandvideo.R;
import com.audioandvideo.two.Tool.AudioRecordTool;
/**
* 录音Activity
*/
public class AudioRecordActivity extends AppCompatActivity implements View.OnClickListener{
private Button btnStart;
private Button btnStop;
private AudioRecordTool audioRecordTool;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_audio_record);
btnStart = findViewById(R.id.btn_start);
btnStop = findViewById(R.id.btn_stop);
audioRecordTool = new AudioRecordTool();
//初始化
audioRecordTool.createAudioRecord();
btnStart.setOnClickListener(this);
btnStop.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btn_start:
audioRecordTool.start();
break;
case R.id.btn_stop:
audioRecordTool.stop();
break;
}
}
@Override
protected void onDestroy() {
super.onDestroy();
audioRecordTool.stop();
}
}
页面只有2个按钮，一个开始录音按钮，一个停止录音按钮
测试
手机有文件，能播放。
