Android-音频相关开发

问题

  1. 如何实现录音，并获取pcm数据
  2. 如何上传（要求用二进制流的content-type上传pcm数据）：Content-Type: application/octet-stream
  3. 获取到服务器的音频信息之后如何播放（音频可能有两种，一种url，一种pcm数据流）

实现录音，存成pcm数据

有两个选择：

  • medioRecord
  • audioRecord

区别：

  • medioRecord相对audioRecord更加上层一点，底层使用的是audioRecord
  • medioRecord会把对音频数据做一些编码相关的处理，可以通过它获取到可以直接播放的音频文件，具体格式参见tip1，而audioRecord获取到的是pcm格式数据，该格式数据不能直接播放
  • audioRecord具有实时性

结论：

​ 因为录制的音频要上传给服务端，而且服务端要求pcm流数据，所有选择audioRecord实现。

注意

客户端跟服务端的pcm数据格式一定要一致（采样率，声道等）（坑了我好久。。。）

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package com.example.mylibrary.audio;

import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Environment;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
* pcm录音utils
* @anthor kb_jay
* create at 2018/8/21 上午10:37
*/
public class AudioRecordUtil {
    private static AudioRecordUtil mInstance;
    private AudioRecord recorder;
    //声音源
    private static int audioSource = MediaRecorder.AudioSource.MIC;
    //录音的采样频率
    private static int audioRate = 16000;
    //录音的声道，单声道
    private static int audioChannel = AudioFormat.CHANNEL_IN_DEFAULT;
    //量化的精度
    private static int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
    //缓存的大小
    private static int bufferSize = AudioRecord.getMinBufferSize(audioRate, audioChannel, audioFormat);
    //记录播放状态
    private boolean isRecording = false;
    //数字信号数组
    private byte[] noteArray;
    //PCM文件
    private File pcmFile;
    //wav文件
    private File wavFile;
    //文件输出流
    private OutputStream os;
    //文件根目录
    private String basePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/xiaoIceStory/";

    //pcm文件目录
    private String inFileName = basePath + "/encode.pcm";

    public String getPcmFilePath() {
        return inFileName;
    }

    private AudioRecordUtil() {
        //创建文件
        createFile();
    }

    //创建文件夹,首先创建目录，然后创建对应的文件
    private void createFile() {
        File baseFile = new File(basePath);
        if (!baseFile.exists()) {
            baseFile.mkdirs();
        }
        pcmFile = new File(basePath + "/encode.pcm");

        if (pcmFile.exists()) {
            pcmFile.delete();
        }
        try {
            pcmFile.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public  static AudioRecordUtil getInstance() {
        if (mInstance == null) {
            synchronized (AudioRecordUtil.class){
                if(mInstance==null){
                    mInstance = new AudioRecordUtil();
                }
            }
        }
        return mInstance;
    }

    //读取录音数字数据线程
    class WriteThread implements Runnable {
        @Override
        public void run() {
            writeData();
        }
    }

    //录音线程执行体
    private void writeData() {
        noteArray = new byte[bufferSize];
        //建立文件输出流
        try {
            os = new BufferedOutputStream(new FileOutputStream(pcmFile));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        while (isRecording) {
            int recordSize = recorder.read(noteArray, 0, bufferSize);
            if (recordSize > 0) {
                try {
                    os.write(noteArray);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        if (os != null) {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //开始录音
    public void startRecord() {
        isRecording = true;
        recorder = new AudioRecord(audioSource, audioRate,
                audioChannel, audioFormat, bufferSize);
        recorder.startRecording();
    }

    //记录数据
    public void recordData() {
        new Thread(new WriteThread()).start();
    }

    //停止录音
    public void stopRecord() {
        if (recorder != null) {
            isRecording = false;
            recorder.stop();
            recorder.release();

        }
    }
}

参考：

https://developer.android.com/reference/android/media/MediaRecorder

https://developer.android.com/guide/topics/media/mediarecorder

https://www.jianshu.com/p/90c4071c7768

http://www.cnblogs.com/renhui/p/7463287.html

实现上传音频pcm数据流

  • content-type用来指定数据格式,比如multipart/form-data，application/json,application/octet-stream(二进制流)，application/text等。详细参见http://www.runoob.com/http/http-content-type.html
  • okhttp中提供了设置content-type的方法：
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/** Returns a new request body that transmits {@code content}. */
public static RequestBody create(final @Nullable MediaType contentType, final byte[] content) {
   return create(contentType, content, 0, content.length);
}

因为服务端对requestBody格式有要求：

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--this-is-a-boundary
Content-Disposition: form-data; name="metadata"
Content-Type: application/json; charset=UTF-8

{xxx这是一段json格式的数据xxx}

--this-is-a-boundary
Content-Disposition: form-data; name="audio"
Content-Type: application/octet-stream

pcm数据
--this-is-a-boundary--

所以采用如下方式：

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@POST()
Flowable<ResponseBody> uploadPcm(@Url String url, @Body RequestBody body, @Header("xxx") String appId);

其中的body如下：

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requestBody = RequestBody.create(MediaType.parse("*/*;charset=utf-8"), contentBytes, 0, contentBytes.length);
//contentBytes为服务端要求的requestBody对应的byte数组。

播放pcm数据使用AudioTrack

注意pcm数据格式需要跟服务端的一致：声道，采样率等。。。

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package com.ms.xiaoicestorydemo.util;

import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;

import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * pcm数据播放utils
 *
 * @anthor kb_jay
 * create at 2018/8/21 上午10:38
 */
public class AudioPlayUtils {

    private  final int BUFFER_SIZE = 1024 * 2;
    private  byte[] mBuffer = new byte[BUFFER_SIZE];
    private AudioPlayUtils() {
    }

    private static AudioPlayUtils instance;

    public static AudioPlayUtils getInstance() {
        if (instance == null) {
            synchronized (AudioPlayUtils.class) {
                if (instance == null) {
                    instance = new AudioPlayUtils();
                }
            }
        }
        return instance;
    }

    //播放pcm文件音频
    public void playPcmFileAudio(RandomAccessFile raf) {
        int streamType = AudioManager.STREAM_MUSIC;
        int simpleRate = 16000;
        int channelConfig = AudioFormat.CHANNEL_IN_DEFAULT;
        int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
        int mode = AudioTrack.MODE_STREAM;

        int minBufferSize = AudioTrack.getMinBufferSize(simpleRate, channelConfig, audioFormat);
        AudioTrack audioTrack = new AudioTrack(streamType, simpleRate, channelConfig, audioFormat,
                Math.max(minBufferSize, BUFFER_SIZE), mode);
        audioTrack.play();
        try {
            int read;
            while ((read = raf.read(mBuffer)) > 0) {
                audioTrack.write(mBuffer, 0, read);
            }
        } catch (RuntimeException | IOException e) {
            e.printStackTrace();
        }
    }
}

播放在线音频

使用exoMedia：git地址：https://github.com/brianwernick/ExoMedia

其中使用的是exoPlayer：git地址：https://github.com/google/ExoPlayer

tip1

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    public static final int DEFAULT = 0;
    /** 3GPP media file format*/
    public static final int THREE_GPP = 1;
    /** MPEG4 media file format*/
    public static final int MPEG_4 = 2;
    /** The following formats are audio only .aac or .amr formats */
    /**
     * AMR NB file format
     * @deprecated  Deprecated in favor of MediaRecorder.OutputFormat.AMR_NB
     */
    public static final int RAW_AMR = 3;
    /** AMR NB file format */
    public static final int AMR_NB = 3;
    /** AMR WB file format */
    public static final int AMR_WB = 4;
    /** @hide AAC ADIF file format */
    public static final int AAC_ADIF = 5;
    /** AAC ADTS file format */
    public static final int AAC_ADTS = 6;
    /** @hide Stream over a socket, limited to a single stream */
    public static final int OUTPUT_FORMAT_RTP_AVP = 7;
    /** H.264/AAC data encapsulated in MPEG2/TS */
    public static final int MPEG_2_TS = 8;
    /** VP8/VORBIS data in a WEBM container */
    public static final int WEBM = 9;
};