Android音频实时传输与播放（三）：AMR硬编码与硬解码【转】

Android音频实时传输与播放（三）：AMR硬编码与硬解码

分类： Android 流媒体2012-07-16 22:17 4779人阅读 评论(10) 收藏 举报

androidexceptionbuffernullsocketfile

转载请注明出处！

原文链接：http://blog.csdn.net/zgyulongfei/article/details/7753163

 

在Android中我所知道的音频编解码有两种方式：

（一）使用AudioRecord采集音频，用这种方式采集的是未经压缩的音频流；用AudioTrack播放实时音频流。用这两个类的话，如果需要对音频进行编解码，就需要自己移植编解码库了，比如可以移植ilbc，speex等开源编解码库。

（二）使用MediaRecorder获取编码后的AMR音频，但由于MediaRecorder的特点，只能将流保存到文件中，但通过其他方式是可以获取到实时音频流的，这篇文章将介绍用LocalSocket的方法来实现；使用MediaPlayer来播放AMR音频流，但同样MediaPlayer也只能播放文件流，因此我用缓存的方式来播放音频。

以上两种方式各有利弊，使用方法（一）需移植编解码库，但可以播放实时音频流；使用方法（二）直接硬编硬解码效率高，但是需要对文件进行操作。

PS：这篇文章只是给大家一个参考，仅供学习之用，如果真正用到项目中还有很多地方需要优化。

我强烈推荐播放音频时候用方法（一），方法（二）虽然能够实现功能，但是实现方式不太好。

 

接下来看代码：

编码器：

package cn.edu.xmu.zgy.audio.encoder;

import java.io.DataInputStream;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

import cn.edu.xmu.zgy.config.CommonConfig;

import android.app.Activity;
import android.media.MediaRecorder;
import android.net.LocalServerSocket;
import android.net.LocalSocket;
import android.net.LocalSocketAddress;
import android.util.Log;
import android.widget.Toast;

//blog.csdn.net/zgyulongfei
//Email: zgyulongfei@gmail.com

public class AmrAudioEncoder {
    private static final String TAG = "ArmAudioEncoder";

    private static AmrAudioEncoder amrAudioEncoder = null;

    private Activity activity;

    private MediaRecorder audioRecorder;

    private boolean isAudioRecording;

    private LocalServerSocket lss;
    private LocalSocket sender, receiver;

    private AmrAudioEncoder() {
    }

    public static AmrAudioEncoder getArmAudioEncoderInstance() {
        if (amrAudioEncoder == null) {
            synchronized (AmrAudioEncoder.class) {
                if (amrAudioEncoder == null) {
                    amrAudioEncoder = new AmrAudioEncoder();
                }
            }
        }
        return amrAudioEncoder;
    }

    public void initArmAudioEncoder(Activity activity) {
        this.activity = activity;
        isAudioRecording = false;
    }

    public void start() {
        if (activity == null) {
            showToastText("音频编码器未初始化，请先执行init方法");
            return;
        }

        if (isAudioRecording) {
            showToastText("音频已经开始编码，无需再次编码");
            return;
        }

        if (!initLocalSocket()) {
            showToastText("本地服务开启失败");
            releaseAll();
            return;
        }

        if (!initAudioRecorder()) {
            showToastText("音频编码器初始化失败");
            releaseAll();
            return;
        }

        this.isAudioRecording = true;
        startAudioRecording();
    }

    private boolean initLocalSocket() {
        boolean ret = true;
        try {
            releaseLocalSocket();

            String serverName = "armAudioServer";
            final int bufSize = 1024;

            lss = new LocalServerSocket(serverName);

            receiver = new LocalSocket();
            receiver.connect(new LocalSocketAddress(serverName));
            receiver.setReceiveBufferSize(bufSize);
            receiver.setSendBufferSize(bufSize);

            sender = lss.accept();
            sender.setReceiveBufferSize(bufSize);
            sender.setSendBufferSize(bufSize);
        } catch (IOException e) {
            ret = false;
        }
        return ret;
    }

    private boolean initAudioRecorder() {
        if (audioRecorder != null) {
            audioRecorder.reset();
            audioRecorder.release();
        }
        audioRecorder = new MediaRecorder();
        audioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        audioRecorder.setOutputFormat(MediaRecorder.OutputFormat.RAW_AMR);
        final int mono = 1;
        audioRecorder.setAudioChannels(mono);
        audioRecorder.setAudioSamplingRate(8000);
        audioRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        audioRecorder.setOutputFile(sender.getFileDescriptor());

        boolean ret = true;
        try {
            audioRecorder.prepare();
            audioRecorder.start();
        } catch (Exception e) {
            releaseMediaRecorder();
            showToastText("手机不支持录音此功能");
            ret = false;
        }
        return ret;
    }

    private void startAudioRecording() {
        new Thread(new AudioCaptureAndSendThread()).start();
    }

    public void stop() {
        if (isAudioRecording) {
            isAudioRecording = false;
        }
        releaseAll();
    }

    private void releaseAll() {
        releaseMediaRecorder();
        releaseLocalSocket();
        amrAudioEncoder = null;
    }

    private void releaseMediaRecorder() {
        try {
            if (audioRecorder == null) {
                return;
            }
            if (isAudioRecording) {
                audioRecorder.stop();
                isAudioRecording = false;
            }
            audioRecorder.reset();
            audioRecorder.release();
            audioRecorder = null;
        } catch (Exception err) {
            Log.d(TAG, err.toString());
        }
    }

    private void releaseLocalSocket() {
        try {
            if (sender != null) {
                sender.close();
            }
            if (receiver != null) {
                receiver.close();
            }
            if (lss != null) {
                lss.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        sender = null;
        receiver = null;
        lss = null;
    }

    private boolean isAudioRecording() {
        return isAudioRecording;
    }

    private void showToastText(String msg) {
        Toast.makeText(activity, msg, Toast.LENGTH_SHORT).show();
    }

    private class AudioCaptureAndSendThread implements Runnable {
        public void run() {
            try {
                sendAmrAudio();
            } catch (Exception e) {
                Log.e(TAG, "sendAmrAudio() 出错");
            }
        }

        private void sendAmrAudio() throws Exception {
            DatagramSocket udpSocket = new DatagramSocket();
            DataInputStream dataInput = new DataInputStream(receiver.getInputStream());

            skipAmrHead(dataInput);

            final int SEND_FRAME_COUNT_ONE_TIME = 10;// 每次发送10帧的数据，1帧大约32B
            // AMR格式见博客：http://blog.csdn.net/dinggo/article/details/1966444
            final int BLOCK_SIZE[] = { 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 };

            byte[] sendBuffer = new byte[1024];
            while (isAudioRecording()) {
                int offset = 0;
                for (int index = 0; index < SEND_FRAME_COUNT_ONE_TIME; ++index) {
                    if (!isAudioRecording()) {
                        break;
                    }
                    dataInput.read(sendBuffer, offset, 1);
                    int blockIndex = (int) (sendBuffer[offset] >> 3) & 0x0F;
                    int frameLength = BLOCK_SIZE[blockIndex];
                    readSomeData(sendBuffer, offset + 1, frameLength, dataInput);
                    offset += frameLength + 1;
                }
                udpSend(udpSocket, sendBuffer, offset);
            }
            udpSocket.close();
            dataInput.close();
            releaseAll();
        }

        private void skipAmrHead(DataInputStream dataInput) {
            final byte[] AMR_HEAD = new byte[] { 0x23, 0x21, 0x41, 0x4D, 0x52, 0x0A };
            int result = -1;
            int state = 0;
            try {
                while (-1 != (result = dataInput.readByte())) {
                    if (AMR_HEAD[0] == result) {
                        state = (0 == state) ? 1 : 0;
                    } else if (AMR_HEAD[1] == result) {
                        state = (1 == state) ? 2 : 0;
                    } else if (AMR_HEAD[2] == result) {
                        state = (2 == state) ? 3 : 0;
                    } else if (AMR_HEAD[3] == result) {
                        state = (3 == state) ? 4 : 0;
                    } else if (AMR_HEAD[4] == result) {
                        state = (4 == state) ? 5 : 0;
                    } else if (AMR_HEAD[5] == result) {
                        state = (5 == state) ? 6 : 0;
                    }

                    if (6 == state) {
                        break;
                    }
                }
            } catch (Exception e) {
                Log.e(TAG, "read mdat error...");
            }
        }

        private void readSomeData(byte[] buffer, int offset, int length, DataInputStream dataInput) {
            int numOfRead = -1;
            while (true) {
                try {
                    numOfRead = dataInput.read(buffer, offset, length);
                    if (numOfRead == -1) {
                        Log.d(TAG, "amr...no data get wait for data coming.....");
                        Thread.sleep(100);
                    } else {
                        offset += numOfRead;
                        length -= numOfRead;
                        if (length <= 0) {
                            break;
                        }
                    }
                } catch (Exception e) {
                    Log.e(TAG, "amr..error readSomeData");
                    break;
                }
            }
        }

        private void udpSend(DatagramSocket udpSocket, byte[] buffer, int sendLength) {
            try {
                InetAddress ip = InetAddress.getByName(CommonConfig.SERVER_IP_ADDRESS.trim());
                int port = CommonConfig.AUDIO_SERVER_UP_PORT;

                byte[] sendBuffer = new byte[sendLength];
                System.arraycopy(buffer, 0, sendBuffer, 0, sendLength);

                DatagramPacket packet = new DatagramPacket(sendBuffer, sendLength);
                packet.setAddress(ip);
                packet.setPort(port);
                udpSocket.send(packet);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

关于编码器：前面提到了，MediaRecorder的硬编码的方式只能将码流保存到文件中，这里用了LocalSocket的方式将流保存到内存中，然后从缓冲中读取码流。由于保存的格式RAW_AMR格式的，因此需要对读取到的数据进行解析，从而获得真正的音频流。想了解AMR音频码流格式的，可以查看代码中附上的网页链接。由于压缩过的码流很小，因此我在实现的时候，组合了int SEND_FRAME_COUNT_ONE_TIME = 10帧的码流后才往外发送，这样的方式造成的延迟会加重，大家可以根据自己的需要进行修改。造成延迟的另一因素是LocalSocket缓冲的大小，在这里我设置的大小是final int bufSize = 1024;代码写的很清楚详细，有疑问的可以提出。

播放器：

package cn.edu.xmu.zgy.audio.player;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.Socket;

import cn.edu.xmu.zgy.config.CommonConfig;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Handler;
import android.util.Log;

//blog.csdn.net/zgyulongfei
//Email: zgyulongfei@gmail.com

public class AmrAudioPlayer {
    private static final String TAG = "AmrAudioPlayer";

    private static AmrAudioPlayer playerInstance = null;

    private long alreadyReadByteCount = 0;

    private MediaPlayer audioPlayer;
    private Handler handler = new Handler();

    private final String cacheFileName = "audioCacheFile";
    private File cacheFile;
    private int cacheFileCount = 0;

    // 用来记录是否已经从cacheFile中复制数据到另一个cache中
    private boolean hasMovedTheCacheFlag;

    private boolean isPlaying;
    private Activity activity;

    private boolean isChaingCacheToAnother;

    private AmrAudioPlayer() {
    }

    public static AmrAudioPlayer getAmrAudioPlayerInstance() {
        if (playerInstance == null) {
            synchronized (AmrAudioPlayer.class) {
                if (playerInstance == null) {
                    playerInstance = new AmrAudioPlayer();
                }
            }
        }
        return playerInstance;
    }

    public void initAmrAudioPlayer(Activity activity) {
        this.activity = activity;
        deleteExistCacheFile();
        initCacheFile();
    }

    private void deleteExistCacheFile() {
        File cacheDir = activity.getCacheDir();
        File[] needDeleteCacheFiles = cacheDir.listFiles();
        for (int index = 0; index < needDeleteCacheFiles.length; ++index) {
            File cache = needDeleteCacheFiles[index];
            if (cache.isFile()) {
                if (cache.getName().contains(cacheFileName.trim())) {
                    Log.e(TAG, "delete cache file: " + cache.getName());
                    cache.delete();
                }
            }
        }
        needDeleteCacheFiles = null;
    }

    private void initCacheFile() {
        cacheFile = null;
        cacheFile = new File(activity.getCacheDir(), cacheFileName);
    }

    public void start() {
        isPlaying = true;
        isChaingCacheToAnother = false;
        setHasMovedTheCacheToAnotherCache(false);
        new Thread(new NetAudioPlayerThread()).start();
    }

    public void stop() {
        isPlaying = false;
        isChaingCacheToAnother = false;
        setHasMovedTheCacheToAnotherCache(false);
        releaseAudioPlayer();
        deleteExistCacheFile();
        cacheFile = null;
        handler = null;
    }

    private void releaseAudioPlayer() {
        playerInstance = null;
        if (audioPlayer != null) {
            try {
                if (audioPlayer.isPlaying()) {
                    audioPlayer.pause();
                }
                audioPlayer.release();
                audioPlayer = null;
            } catch (Exception e) {
            }
        }
    }

    private boolean hasMovedTheCacheToAnotherCache() {
        return hasMovedTheCacheFlag;
    }

    private void setHasMovedTheCacheToAnotherCache(boolean result) {
        hasMovedTheCacheFlag = result;
    }

    private class NetAudioPlayerThread implements Runnable {
        // 从接受数据开始计算，当缓存大于INIT_BUFFER_SIZE时候开始播放
        private final int INIT_AUDIO_BUFFER = 2 * 1024;
        // 剩1秒的时候播放新的缓存的音乐
        private final int CHANGE_CACHE_TIME = 1000;

        public void run() {
            try {
                Socket socket = createSocketConnectToServer();
                receiveNetAudioThenPlay(socket);
            } catch (Exception e) {
                Log.e(TAG, e.getMessage() + "从服务端接受音频失败。。。");
            }
        }

        private Socket createSocketConnectToServer() throws Exception {
            String hostName = CommonConfig.SERVER_IP_ADDRESS;
            InetAddress ipAddress = InetAddress.getByName(hostName);
            int port = CommonConfig.AUDIO_SERVER_DOWN_PORT;
            Socket socket = new Socket(ipAddress, port);
            return socket;
        }

        private void receiveNetAudioThenPlay(Socket socket) throws Exception {
            InputStream inputStream = socket.getInputStream();
            FileOutputStream outputStream = new FileOutputStream(cacheFile);

            final int BUFFER_SIZE = 100 * 1024;// 100kb buffer size
            byte[] buffer = new byte[BUFFER_SIZE];

            // 收集了10*350b了之后才开始更换缓存
            int testTime = 10;
            try {
                alreadyReadByteCount = 0;
                while (isPlaying) {
                    int numOfRead = inputStream.read(buffer);
                    if (numOfRead <= 0) {
                        break;
                    }
                    alreadyReadByteCount += numOfRead;
                    outputStream.write(buffer, 0, numOfRead);
                    outputStream.flush();
                    try {
                        if (testTime++ >= 10) {
                            Log.e(TAG, "cacheFile=" + cacheFile.length());
                            testWhetherToChangeCache();
                            testTime = 0;
                        }
                    } catch (Exception e) {
                        // TODO: handle exception
                    }

                    // 如果复制了接收网络流的cache，则执行此操作
                    if (hasMovedTheCacheToAnotherCache() && !isChaingCacheToAnother) {
                        if (outputStream != null) {
                            outputStream.close();
                            outputStream = null;
                        }
                        // 将接收网络流的cache删除，然后重0开始存储
                        // initCacheFile();
                        outputStream = new FileOutputStream(cacheFile);
                        setHasMovedTheCacheToAnotherCache(false);
                        alreadyReadByteCount = 0;
                    }

                }
            } catch (Exception e) {
                errorOperator();
                e.printStackTrace();
                Log.e(TAG, "socket disconnect...:" + e.getMessage());
                throw new Exception("socket disconnect....");
            } finally {
                buffer = null;
                if (socket != null) {
                    socket.close();
                }
                if (inputStream != null) {
                    inputStream.close();
                    inputStream = null;
                }
                if (outputStream != null) {
                    outputStream.close();
                    outputStream = null;
                }
                stop();
            }
        }

        private void testWhetherToChangeCache() throws Exception {
            if (audioPlayer == null) {
                firstTimeStartPlayer();
            } else {
                changeAnotherCacheWhenEndOfCurrentCache();
            }
        }

        private void firstTimeStartPlayer() throws Exception {
            // 当缓存已经大于INIT_AUDIO_BUFFER则开始播放
            if (alreadyReadByteCount >= INIT_AUDIO_BUFFER) {
                Runnable r = new Runnable() {
                    public void run() {
                        try {
                            File firstCacheFile = createFirstCacheFile();
                            // 设置已经从cache中复制数据，然后会删除这个cache
                            setHasMovedTheCacheToAnotherCache(true);
                            audioPlayer = createAudioPlayer(firstCacheFile);
                            audioPlayer.start();
                        } catch (Exception e) {
                            Log.e(TAG, e.getMessage() + " :in firstTimeStartPlayer() fun");
                        } finally {
                        }
                    }
                };
                handler.post(r);
            }
        }

        private File createFirstCacheFile() throws Exception {
            String firstCacheFileName = cacheFileName + (cacheFileCount++);
            File firstCacheFile = new File(activity.getCacheDir(), firstCacheFileName);
            // 为什么不直接播放cacheFile，而要复制cacheFile到一个新的cache，然后播放此新的cache？
            // 是为了防止潜在的读/写错误，可能在写入cacheFile的时候，
            // MediaPlayer正试图读数据， 这样可以防止死锁的发生。
            moveFile(cacheFile, firstCacheFile);
            return firstCacheFile;

        }

        private void moveFile(File oldFile, File newFile) throws IOException {
            if (!oldFile.exists()) {
                throw new IOException("oldFile is not exists. in moveFile() fun");
            }
            if (oldFile.length() <= 0) {
                throw new IOException("oldFile size = 0. in moveFile() fun");
            }
            BufferedInputStream reader = new BufferedInputStream(new FileInputStream(oldFile));
            BufferedOutputStream writer = new BufferedOutputStream(new FileOutputStream(newFile,
                    false));

            final byte[] AMR_HEAD = new byte[] { 0x23, 0x21, 0x41, 0x4D, 0x52, 0x0A };
            writer.write(AMR_HEAD, 0, AMR_HEAD.length);
            writer.flush();

            try {
                byte[] buffer = new byte[1024];
                int numOfRead = 0;
                Log.d(TAG, "POS...newFile.length=" + newFile.length() + "  old=" + oldFile.length());
                while ((numOfRead = reader.read(buffer, 0, buffer.length)) != -1) {
                    writer.write(buffer, 0, numOfRead);
                    writer.flush();
                }
                Log.d(TAG, "POS..AFTER...newFile.length=" + newFile.length());
            } catch (IOException e) {
                Log.e(TAG, "moveFile error.. in moveFile() fun." + e.getMessage());
                throw new IOException("moveFile error.. in moveFile() fun.");
            } finally {
                if (reader != null) {
                    reader.close();
                    reader = null;
                }
                if (writer != null) {
                    writer.close();
                    writer = null;
                }
            }
        }

        private MediaPlayer createAudioPlayer(File audioFile) throws IOException {
            MediaPlayer mPlayer = new MediaPlayer();

            // It appears that for security/permission reasons, it is better to
            // pass
            // a FileDescriptor rather than a direct path to the File.
            // Also I have seen errors such as "PVMFErrNotSupported" and
            // "Prepare failed.: status=0x1" if a file path String is passed to
            // setDataSource(). So unless otherwise noted, we use a
            // FileDescriptor here.
            FileInputStream fis = new FileInputStream(audioFile);
            mPlayer.reset();
            mPlayer.setDataSource(fis.getFD());
            mPlayer.prepare();
            return mPlayer;
        }

        private void changeAnotherCacheWhenEndOfCurrentCache() throws IOException {
            // 检查当前cache剩余时间
            long theRestTime = audioPlayer.getDuration() - audioPlayer.getCurrentPosition();
            Log.e(TAG, "theRestTime=" + theRestTime + "  isChaingCacheToAnother="
                    + isChaingCacheToAnother);
            if (!isChaingCacheToAnother && theRestTime <= CHANGE_CACHE_TIME) {
                isChaingCacheToAnother = true;

                Runnable r = new Runnable() {
                    public void run() {
                        try {
                            File newCacheFile = createNewCache();
                            // 设置已经从cache中复制数据，然后会删除这个cache
                            setHasMovedTheCacheToAnotherCache(true);
                            transferNewCacheToAudioPlayer(newCacheFile);
                        } catch (Exception e) {
                            Log.e(TAG, e.getMessage()
                                    + ":changeAnotherCacheWhenEndOfCurrentCache() fun");
                        } finally {
                            deleteOldCache();
                            isChaingCacheToAnother = false;
                        }
                    }
                };
                handler.post(r);
            }
        }

        private File createNewCache() throws Exception {
            // 将保存网络数据的cache复制到newCache中进行播放
            String newCacheFileName = cacheFileName + (cacheFileCount++);
            File newCacheFile = new File(activity.getCacheDir(), newCacheFileName);
            Log.e(TAG, "before moveFile............the size=" + cacheFile.length());
            moveFile(cacheFile, newCacheFile);
            return newCacheFile;
        }

        private void transferNewCacheToAudioPlayer(File newCacheFile) throws Exception {
            MediaPlayer oldPlayer = audioPlayer;

            try {
                audioPlayer = createAudioPlayer(newCacheFile);
                audioPlayer.start();
            } catch (Exception e) {
                Log.e(TAG, "filename=" + newCacheFile.getName() + " size=" + newCacheFile.length());
                Log.e(TAG, e.getMessage() + " " + e.getCause() + " error start..in transfanNer..");
            }
            try {
                oldPlayer.pause();
                oldPlayer.reset();
                oldPlayer.release();
            } catch (Exception e) {
                Log.e(TAG, "ERROR release oldPlayer.");
            } finally {
                oldPlayer = null;
            }
        }

        private void deleteOldCache() {
            int oldCacheFileCount = cacheFileCount - 1;
            String oldCacheFileName = cacheFileName + oldCacheFileCount;
            File oldCacheFile = new File(activity.getCacheDir(), oldCacheFileName);
            if (oldCacheFile.exists()) {
                oldCacheFile.delete();
            }
        }

        private void errorOperator() {
        }
    }

}

关于播放器：由于MediaPlayer的限制，我用了cache的方式来实现音频的实时播放。即把获取到的音频流首先保存到文件中，然后当保存到一定大小的时候就播放之，类似于QQ播放器那样有缓存的，只不过我这里的处理得挺粗糙。代码写的也挺详细了，如果有疑问也可以提出来。

 

注：编码器和播放器的编写，我都是站在巨人的肩膀上完成的，参考了一些其他资料。

 

在后面一篇文章中，我将附上服务器和客户端的所有代码。

希望朋友们看完能提出意见和建议，也希望看完能有所收获 ^_^