android 使用MediaCodec（根据设备状况硬编解码）来转码音频（MP3 to aac），并同时裁剪音频
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第一次写这样的博文，写得不好，望大家及时指出博文中的错误，以便于相互学习。
本来主要介绍如何使用mediacodec来转码音频，同时实现音频的裁剪。对于mediacodec相信大家都不陌生，没做过也听过。
转码音频需要的知识点
1、音频基础知识，什么是pcm，什么是音频格式（MP3、aac等），这里给大家推荐一篇博文，http://blog.csdn.net/kevindgk/article/details/52924779。
2、mediacodec的基础知识和api调用，mediacodec是典型的CS模式，也就是客户端-服务器模式，建议大家多看看官网api，
这里给大家推荐一篇中文版的api，MediaCodec中文api
转码流程
解码线程：FILE—解码—PCM队列
编码线程：PCM队列—编码—FILE
系统版本和相关Api类
sdk版本>=16；MediaCodec、MediaExtractor
解码线程
主要流程是通过MediaExtractor读取一帧数据，然后进行解码并放入PCM队列，流程分为prepare—decode—release;
相关代码分别如下：
主要线程里面的流程：
@Override public void run() { TransAacHandlerPure.logMsg("decodec run"); if (listener != null) { listener.onStart(); } boolean isPrepare = false; try { prepare();//初始化 isPrepare = true; } catch (IOException e) { e.printStackTrace(); } TransAacHandlerPure.logMsg("decodec isPrepare " + isPrepare); if (isPrepare) { decode();//解码 } release();//释放资源 if (!isPrepare && listener != null) { listener.onFail(); } isFinish = true; }prepare里面的代码如下：
private void prepare() throws IOException { extractor = new MediaExtractor(); extractor.setDataSource(srcFile); int numTracks = extractor.getTrackCount(); for (int i = 0; i < numTracks; i++) { MediaFormat format = extractor.getTrackFormat(i); String mine = format.getString(MediaFormat.KEY_MIME); if (!TextUtils.isEmpty(mine) && mine.startsWith("audio")) { extractor.selectTrack(i); try { duration = format.getInteger(MediaFormat.KEY_DURATION) / 1000; } catch (Exception e) { e.printStackTrace(); MediaPlayer mediaPlayer = new MediaPlayer(); mediaPlayer.setDataSource(srcFile); mediaPlayer.prepare(); duration = mediaPlayer.getDuration(); mediaPlayer.release(); } codec = MediaCodec.createDecoderByType(mine); codec.configure(format, null, null, 0); codec.start(); TransAacHandlerPure.logMsg("New decode codec start:" + format.toString()); break; } }// createFile(outFile + ".pcm", true);//测试 输出pcm格式// mOutput = new DataOutputStream(new FileOutputStream(outFile + ".pcm")); }decode方法如下： private void decode() { ByteBuffer[] inputBuffers = codec.getInputBuffers(); ByteBuffer[] outputBuffers = codec.getOutputBuffers(); MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); TransAacHandlerPure.logMsg("loopDecode start"); if (rangeStart > 0) {//如果有裁剪，seek到裁剪的地方 extractor.seekTo(rangeStart * 1000, MediaExtractor.SEEK_TO_CLOSEST_SYNC); } boolean isEOS = false; while (true) { long timestamp = 0; if (!isEOS) { int inIndex = codec.dequeueInputBuffer(TIME_OUT); if (inIndex >= 0) { ByteBuffer buffer = inputBuffers[inIndex]; int sampleSize = extractor.readSampleData(buffer, 0); long timestampTemp = extractor.getSampleTime(); timestamp = timestampTemp / 1000; TransAacHandlerPure.logMsg("loopDecode readSampleData end sampleSize " + sampleSize + " buffer.capacity()=" + buffer.capacity()); TransAacHandlerPure.logMsg("loopDecode readSampleData end timestamp" + timestamp); if (rangeEnd > 0 && timestamp > rangeEnd) { sampleSize = -1; } if (sampleSize <= 0) { codec.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); isEOS = true; } else { codec.queueInputBuffer(inIndex, 0, sampleSize, timestampTemp, 0); extractor.advance(); } } } int outIndex = codec.dequeueOutputBuffer(info, TIME_OUT);// TransAacHandlerPure.logMsg(" switch (outIndex)"); switch (outIndex) { case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED: outputBuffers = codec.getOutputBuffers(); TransAacHandlerPure.logMsg("dequeueOutputBuffer INFO_OUTPUT_BUFFERS_CHANGED!"); break; case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED: MediaFormat mf = codec.getOutputFormat(); //开始编码线程 EncodeTask encodeTask = new EncodeTask(outFile, this, listener); int sampleRate = mf.getInteger(MediaFormat.KEY_SAMPLE_RATE); int pcmEncoding = mf.getInteger(MediaFormat.KEY_PCM_ENCODING); int channelCount = mf.getInteger(MediaFormat.KEY_CHANNEL_COUNT); encodeTask.setAudioParams(sampleRate, pcmEncoding, channelCount); new Thread(encodeTask).start(); TransAacHandlerPure.logMsg("New format " + mf.toString()); break; case MediaCodec.INFO_TRY_AGAIN_LATER: TransAacHandlerPure.logMsg("dequeueOutputBuffer timed out!"); break; default: if (last == 0) { last = System.currentTimeMillis(); } long now = System.currentTimeMillis(); TransAacHandlerPure.logMsg("解码时间：" + (now - last) + " info.size " + info.size); last = now; ByteBuffer buffer = outputBuffers[outIndex]; byte[] outData = new byte[info.size]; buffer.get(outData, 0, info.size); codec.releaseOutputBuffer(outIndex, true); try { mOutput.write(outData); } catch (IOException e) { e.printStackTrace(); } pushAvFrame(outData); if (listener != null) { listener.onProgress(rangeEnd > 0 ? (int) rangeEnd : duration, rangeStart > 0 ? (int) (timestamp - rangeStart) : (int) timestamp); } break; } // All decoded frames have been rendered, we can stop playing now if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) { TransAacHandlerPure.logMsg("OutputBuffer BUFFER_FLAG_END_OF_STREAM"); break; } } }release相关代码 private void release() { if (extractor != null) { extractor.release(); extractor = null; } if (codec != null) { codec.stop(); codec.release(); codec = null; } }编码线程
主要流程跟解码线程类似，需要说明的是编码线程开始是在解码返回MediaCodec.INFO_OUTPUT_FORMAT_CHANGED这个状态的时候，因为在这个时候可以拿到编码需要的一些必要参数，如采样率等等，虽然也可以在从MediaExtractor里面拿，但是这样可能有些机型拿不到一些数据，所以我认为在这里拿是比较合适的。闲话不多说，直接看代码：
run方法：
@Override public void run() { boolean isPrepare = false; try { prepare(); isPrepare = true; } catch (IOException e) { e.printStackTrace(); } if (isPrepare && obtain != null) { encode(); } release(); if (listener != null) { if (isPrepare) { listener.onSuccess(); } else { listener.onFail(); } } }prepare方法，关于比特率的设置，大家多参考之前关于音频基础知识的那篇博文，这个直接影响到文件大小和音质 private void prepare() throws IOException { String mime = MediaFormat.MIMETYPE_AUDIO_AAC; encoder = MediaCodec.createEncoderByType(mime); MediaFormat format = MediaFormat.createAudioFormat(mime, sampleRate, channelCount); format.setInteger(MediaFormat.KEY_BIT_RATE, 96000); format.setInteger(MediaFormat.KEY_PCM_ENCODING, pcmEncoding); format.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 20 * 1024); format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC); logMsg(" New " + format.toString()); encoder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE); encoder.start(); createFile(outFile, true); mOutput = new DataOutputStream(new FileOutputStream(outFile)); }encode方法，要注意aac写入的时候需要加入头部分，关于aac格式介绍，大家参考这篇博文-aac格式介绍
private void encode() { boolean isFinish = false; while (true) { if (!isFinish) { byte[] rawData = obtain.getRawFrame(); if (rawData == null) { if (obtain.isFinish()) { isFinish = true; int inIndex = encoder.dequeueInputBuffer(TIME_OUT); encoder.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); } else { try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } continue; } ByteBuffer[] inputBuffers = encoder.getInputBuffers(); int inIndex = encoder.dequeueInputBuffer(TIME_OUT); if (inIndex >= 0) { ByteBuffer inputBuffer = inputBuffers[inIndex]; inputBuffer.clear(); inputBuffer.put(rawData); encoder.queueInputBuffer(inIndex, 0, rawData.length, System.nanoTime(), 0); } } ByteBuffer[] outputBuffers = encoder.getOutputBuffers(); MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); int outIndex = encoder.dequeueOutputBuffer(info, TIME_OUT); if (outIndex >= 0) { if (last == 0) { last = System.currentTimeMillis(); } long now = System.currentTimeMillis(); TransAacHandlerPure.logMsg("编码码时间：" + (now - last) + " info.size " + info.size); last = now; while (outIndex >= 0) { ByteBuffer outputBuffer = outputBuffers[outIndex]; int len = info.size + 7; byte[] outData = new byte[len]; addADTStoPacket(outData, len); outputBuffer.get(outData, 7, info.size); encoder.releaseOutputBuffer(outIndex, false); try { mOutput.write(outData); } catch (Exception e) { e.printStackTrace(); } catch (Error e) { e.printStackTrace(); } outIndex = encoder.dequeueOutputBuffer(info, TIME_OUT); } } if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) { VLog.d("encode OutputBuffer BUFFER_FLAG_END_OF_STREAM"); break; } } }加入aac头方法
/** * 给编码出的aac裸流添加adts头字段 * * @param packet 要空出前7个字节，否则会搞乱数据 * @param packetLen */ private void addADTStoPacket(byte[] packet, int packetLen) { int profile = 2; //AAC LC int freqIdx = 4; //44.1KHz int chanCfg = 2; //CPE packet[0] = (byte) 0xFF; packet[1] = (byte) 0xF9; packet[2] = (byte) (((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2)); packet[3] = (byte) (((chanCfg & 3) << 6) + (packetLen >> 11)); packet[4] = (byte) ((packetLen & 0x7FF) >> 3); packet[5] = (byte) (((packetLen & 7) << 5) + 0x1F); packet[6] = (byte) 0xFC; }release方法
private void release() { if (encoder != null) { encoder.stop(); encoder.release(); encoder = null; } if (mOutput != null) { try { mOutput.flush(); mOutput.close(); } catch (IOException e) { e.printStackTrace(); } mOutput = null; } }几个需要注意的地方
1、编码线程初始化的地方，获取初始化所需的必要参数2、编解码线程之间的同步，由于解码线程一般比编码线程快，所以pcm的队列数据同步显得比较重要，当然了这个消费者模式的基础，相信大家很容易理解
3、aac文件的保存，需要添加头
纯净版MP3ToAAc（可以同时剪辑）所有代码
import android.media.MediaCodec;import android.media.MediaCodecInfo;import android.media.MediaExtractor;import android.media.MediaFormat;import android.media.MediaPlayer;import android.os.Build;import android.support.annotation.RequiresApi;import android.text.TextUtils;import android.util.Log;import java.io.DataOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.nio.ByteBuffer;import java.util.Queue;import java.util.concurrent.LinkedBlockingQueue;/** * 音频转换成为aac编码 * * @author jake * @since 2017/8/3 下午4:28 */@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)public class TransAacHandlerPure { private String srcFile; private String outFile; private long rangeStart = -1; private long rangeEnd = -1; private OnProgressListener listener; public TransAacHandlerPure(String srcFile, String outFile) { this(srcFile, outFile, null); } public TransAacHandlerPure(String srcFile, String outFile, OnProgressListener listener) { this(srcFile, outFile, -1, -1, listener); } public TransAacHandlerPure(String srcFile, String outFile, long rangeStart, long rangeEnd, OnProgressListener listener) { this.srcFile = srcFile; this.outFile = outFile; this.rangeStart = rangeStart; this.rangeEnd = rangeEnd; this.listener = listener; } public void start() { DecodeTask task = new DecodeTask(srcFile, outFile, listener); task.setRangeTime(rangeStart, rangeEnd); new Thread(task).start(); } public void setRangeTime(long rangeStart, long rangeEnd) { this.rangeStart = rangeStart; this.rangeEnd = rangeEnd; } public void setListener(OnProgressListener listener) { this.listener = listener; } private static class DecodeTask implements Runnable, IDataObtain { private static final long TIME_OUT = 5000; private Queue<byte[]> mRawQueue; private MediaExtractor extractor; private boolean isFinish = false; private String srcFile; private MediaCodec codec; private String outFile; private OnProgressListener listener; private long rangeStart; private long rangeEnd; private int duration = 0; private OutputStream mOutput; public void setRangeTime(long rangeStart, long rangeEnd) { this.rangeStart = rangeStart; this.rangeEnd = rangeEnd; } public DecodeTask(String srcFile, String outFile, OnProgressListener listener) { this.srcFile = srcFile; this.outFile = outFile; this.listener = listener; mRawQueue = new LinkedBlockingQueue<>(); } private void pushAvFrame(byte[] frame) { if (frame != null) { int len = mRawQueue.size(); while (len > 10) { try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } len = mRawQueue.size(); } synchronized (mRawQueue) { mRawQueue.offer(frame); } } } @Override public void run() { TransAacHandlerPure.logMsg("decodec run"); if (listener != null) { listener.onStart(); } boolean isPrepare = false; try { prepare(); isPrepare = true; } catch (IOException e) { e.printStackTrace(); } TransAacHandlerPure.logMsg("decodec isPrepare " + isPrepare); if (isPrepare) { decode(); } release(); if (!isPrepare && listener != null) { listener.onFail(); } isFinish = true; } private void release() { if (extractor != null) { extractor.release(); extractor = null; } if (codec != null) { codec.stop(); codec.release(); codec = null; } } private void prepare() throws IOException { extractor = new MediaExtractor(); extractor.setDataSource(srcFile); int numTracks = extractor.getTrackCount(); for (int i = 0; i < numTracks; i++) { MediaFormat format = extractor.getTrackFormat(i); String mine = format.getString(MediaFormat.KEY_MIME); if (!TextUtils.isEmpty(mine) && mine.startsWith("audio")) { extractor.selectTrack(i); try { duration = format.getInteger(MediaFormat.KEY_DURATION) / 1000; } catch (Exception e) { e.printStackTrace(); MediaPlayer mediaPlayer = new MediaPlayer(); mediaPlayer.setDataSource(srcFile); mediaPlayer.prepare(); duration = mediaPlayer.getDuration(); mediaPlayer.release(); } codec = MediaCodec.createDecoderByType(mine); codec.configure(format, null, null, 0); codec.start(); TransAacHandlerPure.logMsg("New decode codec start:" + format.toString()); break; } } createFile(outFile + ".pcm", true);//测试 输出pcm格式 mOutput = new DataOutputStream(new FileOutputStream(outFile + ".pcm")); } long last; private void decode() { ByteBuffer[] inputBuffers = codec.getInputBuffers(); ByteBuffer[] outputBuffers = codec.getOutputBuffers(); MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); TransAacHandlerPure.logMsg("loopDecode start"); if (rangeStart > 0) {//如果有裁剪，seek到裁剪的地方 extractor.seekTo(rangeStart * 1000, MediaExtractor.SEEK_TO_CLOSEST_SYNC); } boolean isEOS = false; while (true) { long timestamp = 0; if (!isEOS) { int inIndex = codec.dequeueInputBuffer(TIME_OUT); if (inIndex >= 0) { ByteBuffer buffer = inputBuffers[inIndex]; int sampleSize = extractor.readSampleData(buffer, 0); long timestampTemp = extractor.getSampleTime(); timestamp = timestampTemp / 1000; TransAacHandlerPure.logMsg("loopDecode readSampleData end sampleSize " + sampleSize + " buffer.capacity()=" + buffer.capacity()); TransAacHandlerPure.logMsg("loopDecode readSampleData end timestamp" + timestamp); if (rangeEnd > 0 && timestamp > rangeEnd) { sampleSize = -1; } if (sampleSize <= 0) { codec.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); isEOS = true; } else { codec.queueInputBuffer(inIndex, 0, sampleSize, timestampTemp, 0); extractor.advance(); } } } int outIndex = codec.dequeueOutputBuffer(info, TIME_OUT);// TransAacHandlerPure.logMsg(" switch (outIndex)"); switch (outIndex) { case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED: outputBuffers = codec.getOutputBuffers(); TransAacHandlerPure.logMsg("dequeueOutputBuffer INFO_OUTPUT_BUFFERS_CHANGED!"); break; case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED: MediaFormat mf = codec.getOutputFormat(); //开始编码线程 EncodeTask encodeTask = new EncodeTask(outFile, this, listener); int sampleRate = mf.getInteger(MediaFormat.KEY_SAMPLE_RATE); int pcmEncoding = mf.getInteger(MediaFormat.KEY_PCM_ENCODING); int channelCount = mf.getInteger(MediaFormat.KEY_CHANNEL_COUNT); encodeTask.setAudioParams(sampleRate, pcmEncoding, channelCount); new Thread(encodeTask).start(); TransAacHandlerPure.logMsg("New format " + mf.toString()); break; case MediaCodec.INFO_TRY_AGAIN_LATER: TransAacHandlerPure.logMsg("dequeueOutputBuffer timed out!"); break; default: if (last == 0) { last = System.currentTimeMillis(); } long now = System.currentTimeMillis(); TransAacHandlerPure.logMsg("解码时间：" + (now - last) + " info.size " + info.size); last = now; ByteBuffer buffer = outputBuffers[outIndex]; byte[] outData = new byte[info.size]; buffer.get(outData, 0, info.size); codec.releaseOutputBuffer(outIndex, true); try { mOutput.write(outData); } catch (IOException e) { e.printStackTrace(); } pushAvFrame(outData); if (listener != null) { listener.onProgress(rangeEnd > 0 ? (int) rangeEnd : duration, rangeStart > 0 ? (int) (timestamp - rangeStart) : (int) timestamp); } break; } // All decoded frames have been rendered, we can stop playing now if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) { TransAacHandlerPure.logMsg("OutputBuffer BUFFER_FLAG_END_OF_STREAM"); break; } } } @Override public byte[] getRawFrame() { int len = mRawQueue.size(); if (len > 0) { synchronized (mRawQueue) { return mRawQueue.poll(); } } return null; } @Override public boolean isFinish() { return isFinish; } } private static void logMsg(String msg) { Log.d(TransAacHandlerPure.class.getSimpleName(), msg); } private static class EncodeTask implements Runnable { private static final long TIME_OUT = 5000; private IDataObtain obtain; private String outFile; private MediaCodec encoder; private OutputStream mOutput; private OnProgressListener listener; private long last; private int sampleRate; private int pcmEncoding; private int channelCount; public EncodeTask(String outFile, IDataObtain obtain, OnProgressListener listener) { this.obtain = obtain; this.outFile = outFile; this.listener = listener; } public void setAudioParams(int sampleRate, int pcmEncoding, int channelCount) { this.sampleRate = sampleRate; this.pcmEncoding = pcmEncoding; this.channelCount = channelCount; } @Override public void run() { boolean isPrepare = false; try { prepare(); isPrepare = true; } catch (IOException e) { e.printStackTrace(); } if (isPrepare && obtain != null) { encode(); } release(); if (listener != null) { if (isPrepare) { listener.onSuccess(); } else { listener.onFail(); } } } private void release() { if (encoder != null) { encoder.stop(); encoder.release(); encoder = null; } if (mOutput != null) { try { mOutput.flush(); mOutput.close(); } catch (IOException e) { e.printStackTrace(); } mOutput = null; } } private void encode() { boolean isFinish = false; while (true) { if (!isFinish) { byte[] rawData = obtain.getRawFrame(); if (rawData == null) { if (obtain.isFinish()) { isFinish = true; int inIndex = encoder.dequeueInputBuffer(TIME_OUT); encoder.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); } else { try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } continue; } ByteBuffer[] inputBuffers = encoder.getInputBuffers(); int inIndex = encoder.dequeueInputBuffer(TIME_OUT); if (inIndex >= 0) { ByteBuffer inputBuffer = inputBuffers[inIndex]; inputBuffer.clear(); inputBuffer.put(rawData); encoder.queueInputBuffer(inIndex, 0, rawData.length, System.nanoTime(), 0); } } ByteBuffer[] outputBuffers = encoder.getOutputBuffers(); MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); int outIndex = encoder.dequeueOutputBuffer(info, TIME_OUT); if (outIndex >= 0) { if (last == 0) { last = System.currentTimeMillis(); } long now = System.currentTimeMillis(); TransAacHandlerPure.logMsg("编码码时间：" + (now - last) + " info.size " + info.size); last = now; while (outIndex >= 0) { ByteBuffer outputBuffer = outputBuffers[outIndex]; int len = info.size + 7; byte[] outData = new byte[len]; addADTStoPacket(outData, len); outputBuffer.get(outData, 7, info.size); encoder.releaseOutputBuffer(outIndex, false); try { mOutput.write(outData); } catch (Exception e) { e.printStackTrace(); } catch (Error e) { e.printStackTrace(); } outIndex = encoder.dequeueOutputBuffer(info, TIME_OUT); } } if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) { VLog.d("encode OutputBuffer BUFFER_FLAG_END_OF_STREAM"); break; } } } /** * 给编码出的aac裸流添加adts头字段 * * @param packet 要空出前7个字节，否则会搞乱数据 * @param packetLen */ private void addADTStoPacket(byte[] packet, int packetLen) { int profile = 2; //AAC LC int freqIdx = 4; //44.1KHz int chanCfg = 2; //CPE packet[0] = (byte) 0xFF; packet[1] = (byte) 0xF9; packet[2] = (byte) (((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2)); packet[3] = (byte) (((chanCfg & 3) << 6) + (packetLen >> 11)); packet[4] = (byte) ((packetLen & 0x7FF) >> 3); packet[5] = (byte) (((packetLen & 7) << 5) + 0x1F); packet[6] = (byte) 0xFC; } private void prepare() throws IOException { String mime = MediaFormat.MIMETYPE_AUDIO_AAC; encoder = MediaCodec.createEncoderByType(mime); MediaFormat format = MediaFormat.createAudioFormat(mime, sampleRate, channelCount); format.setInteger(MediaFormat.KEY_BIT_RATE, 96000); format.setInteger(MediaFormat.KEY_PCM_ENCODING, pcmEncoding); format.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 20 * 1024); format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC); logMsg(" New " + format.toString()); encoder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE); encoder.start(); createFile(outFile, true); mOutput = new DataOutputStream(new FileOutputStream(outFile)); } } private static boolean createFile(String filePath, boolean recreate) { if (TextUtils.isEmpty(filePath)) { return false; } try { File file = new File(filePath); if (file.exists()) { if (recreate) { file.delete(); file.createNewFile(); } } else { // 如果路径不存在，先创建路径 File parentFile = file.getParentFile(); if (!parentFile.exists()) { parentFile.mkdirs(); } file.createNewFile(); } } catch (Exception e) { return false; } return true; } public interface IDataObtain { byte[] getRawFrame(); boolean isFinish(); } public static interface OnProgressListener { void onStart(); void onProgress(int max, int progress); void onSuccess(); void onFail(); }}关于音频裁剪比较简单，如果相同格式不需要转码，直接用MediaExtractor读取相关片段后直接写入即可，这样效率比较高。关于这个转码算法的效率还是比较低，主要原因是编码比较慢，虽然多线程解决了部分问题，但是效率还是比较慢，大家有兴趣可以提出修改意见，咱们一起优化一下这个算法！
由于准备匆忙，很多知识点都没有跟大家说清楚，望大家见谅！希望代码写得不是很乱，大家能看得懂，有不懂的地方，欢迎跟我沟通！
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