Android录屏的三种解决方案

本文总结三种用于安卓录屏的解决方案：

adb shell命令screenrecord
MediaRecorder， MediaProjection
MediaProjection , MediaCodec和MediaMuxer

screenrecord命令

screenrecord是一个shell命令，支持Android4.4(API level 19)以上，录制的视频格式为mp4 ,存放到手机sd卡里，默认录制时间为180s

adb shell screenrecord --size 1280*720 --bit-rate 6000000 --time-limit 30 /sdcard/demo.mp4

 --size 指定视频分辨率；

 --bit-rate 指定视频比特率，默认为4M，该值越小，保存的视频文件越小；

 --time-limit 指定录制时长，若设定大于180，命令不会被执行；

MediaRecorder

MediaProjection是Android5.0后才开放的屏幕采集接口，通过系统级服务MediaProjectionManager进行管理。

录屏过程可以分成两个部分，即通过MediaProjectionManage申请录屏权限，用户允许后开始录制屏幕；然后通过MediaRecorder对音视频数据进行处理。

获取MediaProjectionManager实例

MediaProjectionManager mProjectionManager = (MediaProjectionManager) getSystemService("media_projection");

申请权限

Intent captureIntent = mProjectionManager.createScreenCaptureIntent();
startActivityForResult(captureIntent, LOCAL_REQUEST_CODE);

createScreenCaptureIntent()这个方法会返回一个intent，你可以通过startActivityForResult方法来传递这个intent，为了能开始屏幕捕捉，activity会提示用户是否允许屏幕捕捉（为了防止开发者做一个木马，来捕获用户私人信息），你可以通过getMediaProjection来获取屏幕捕捉的结果。

在onActivityResult中获取结果

@Override
  public void onActivityResult(int requestCode, int resultCode, Intent data) {
    MediaProjection mediaProjection = mProjectionManager.getMediaProjection(resultCode, data);
    if (mediaProjection == null) {
    Log.e(TAG, "media projection is null");
    return;
  }
    File file = new File("xx.mp4"); //录屏生成文件
    mediaRecord = new MediaRecordService(displayWidth, displayHeight, 6000000, 1, 
      mediaProjection, file.getAbsolutePath());
    mediaRecord.start();
}

创建MediaRecorder进程

package com.unionpay.service;
import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.media.MediaRecorder;
import android.media.projection.MediaProjection;
import android.util.Log;
public class MediaRecordService extends Thread {
  private static final String TAG = "MediaRecordService";
  private int mWidth;
  private int mHeight;
  private int mBitRate;
  private int mDpi;
  private String mDstPath;
  private MediaRecorder mMediaRecorder;
  private MediaProjection mMediaProjection;
  private static final int FRAME_RATE = 60; // 60 fps
  private VirtualDisplay mVirtualDisplay;
  public MediaRecordService(int width, int height, int bitrate, int dpi, MediaProjection mp, String dstPath) {
  mWidth = width;
  mHeight = height;
  mBitRate = bitrate;
  mDpi = dpi;
  mMediaProjection = mp;
  mDstPath = dstPath;
  }
  @Override
  public void run() {
  try {
    initMediaRecorder();
    //在mediarecorder.prepare()方法后调用
    mVirtualDisplay = mMediaProjection.createVirtualDisplay(TAG + "-display", mWidth, mHeight, mDpi,
      DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC, mMediaRecorder.getSurface(), null, null);
    Log.i(TAG, "created virtual display: " + mVirtualDisplay);
    mMediaRecorder.start();
    Log.i(TAG, "mediarecorder start");
  } catch (Exception e) {
    e.printStackTrace();
  }
  }
  /**
   * 初始化MediaRecorder
   * 
   * @return
   */
  public void initMediaRecorder() {
  mMediaRecorder = new MediaRecorder();
  mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
  mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
  mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
  mMediaRecorder.setOutputFile(mDstPath);
  mMediaRecorder.setVideoSize(mWidth, mHeight);
  mMediaRecorder.setVideoFrameRate(FRAME_RATE);
  mMediaRecorder.setVideoEncodingBitRate(mBitRate);
  mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
  mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);

  try {
    mMediaRecorder.prepare();
  } catch (Exception e) {
    e.printStackTrace();
  }
  Log.i(TAG, "media recorder" + mBitRate + "kps");
  }

  public void release() {
  if (mVirtualDisplay != null) {
    mVirtualDisplay.release();
    mVirtualDisplay = null;
  }
  if (mMediaRecorder != null) {
    mMediaRecorder.setOnErrorListener(null);
    mMediaProjection.stop();
    mMediaRecorder.reset();
    mMediaRecorder.release();
  }
  if (mMediaProjection != null) {
    mMediaProjection.stop();
    mMediaProjection = null;
  }
  Log.i(TAG, "release");
  }
}

MediaCodec与MediaMuxer

MediaCodec提供对音视频压缩编码和解码功能，MediaMuxer可以将音视频混合生成多媒体文件，生成MP4文件。
与MediaRecorder类似，都需要先通过MediaProjectionManager获取录屏权限，在回调中进行屏幕数据处理。

这里创建另一个进程：

package com.unionpay.service;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.atomic.AtomicBoolean;
import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.media.projection.MediaProjection;
import android.util.Log;
import android.view.Surface;
public class ScreenRecordService extends Thread{
    private static final String TAG = "ScreenRecordService";
  private int mWidth;
  private int mHeight;
  private int mBitRate;
  private int mDpi;
  private String mDstPath;
  private MediaProjection mMediaProjection;
  // parameters for the encoder
  private static final String MIME_TYPE = "video/avc"; // H.264 Advanced
                 // Video Coding
  private static final int FRAME_RATE = 30; // 30 fps
  private static final int IFRAME_INTERVAL = 10; // 10 seconds between
                // I-frames
  private static final int TIMEOUT_US = 10000;
  private MediaCodec mEncoder;
  private Surface mSurface;
  private MediaMuxer mMuxer;
  private boolean mMuxerStarted = false;
  private int mVideoTrackIndex = -1;
  private AtomicBoolean mQuit = new AtomicBoolean(false);
  private MediaCodec.BufferInfo mBufferInfo = new MediaCodec.BufferInfo();
  private VirtualDisplay mVirtualDisplay;
  public ScreenRecordService(int width, int height, int bitrate, int dpi, MediaProjection mp, String dstPath) {
    super(TAG);
    mWidth = width;
    mHeight = height;
    mBitRate = bitrate;
    mDpi = dpi;
    mMediaProjection = mp;
    mDstPath = dstPath;
  }
  /**
   * stop task
   */
  public final void quit() {
    mQuit.set(true);
  }
  @Override
  public void run() {
    try {
    try {
      prepareEncoder();
      mMuxer = new MediaMuxer(mDstPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    mVirtualDisplay = mMediaProjection.createVirtualDisplay(TAG + "-display", mWidth, mHeight, mDpi,
      DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC, mSurface, null, null);
    Log.d(TAG, "created virtual display: " + mVirtualDisplay);
    recordVirtualDisplay();
    } finally {
    release();
    }
  }
  private void recordVirtualDisplay() {
    while (!mQuit.get()) {
    int index = mEncoder.dequeueOutputBuffer(mBufferInfo, TIMEOUT_US);
//   Log.i(TAG, "dequeue output buffer index=" + index);
    if (index == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
      // 后续输出格式变化
      resetOutputFormat();
    } else if (index == MediaCodec.INFO_TRY_AGAIN_LATER) {
      // 请求超时
//     Log.d(TAG, "retrieving buffers time out!");
      try {
      // wait 10ms
      Thread.sleep(10);
      } catch (InterruptedException e) {
      }
    } else if (index >= 0) {
      // 有效输出
      if (!mMuxerStarted) {
      throw new IllegalStateException("MediaMuxer dose not call addTrack(format) ");
      }
      encodeToVideoTrack(index);
      mEncoder.releaseOutputBuffer(index, false);
    }
    }
  }
  /**
   * 硬解码获取实时帧数据并写入mp4文件
   * 
   * @param index
   */
  private void encodeToVideoTrack(int index) {
    // 获取到的实时帧视频数据
    ByteBuffer encodedData = mEncoder.getOutputBuffer(index);
    if ((mBufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
    // The codec config data was pulled out and fed to the muxer
    // when we got
    // the INFO_OUTPUT_FORMAT_CHANGED status.
    // Ignore it.
    Log.d(TAG, "ignoring BUFFER_FLAG_CODEC_CONFIG");
    mBufferInfo.size = 0;
    }
    if (mBufferInfo.size == 0) {
    Log.d(TAG, "info.size == 0, drop it.");
    encodedData = null;
    } else {
//   Log.d(TAG, "got buffer, info: size=" + mBufferInfo.size + ", presentationTimeUs="
//     + mBufferInfo.presentationTimeUs + ", offset=" + mBufferInfo.offset);
    }
    if (encodedData != null) {
    mMuxer.writeSampleData(mVideoTrackIndex, encodedData, mBufferInfo);
    }
  }
  private void resetOutputFormat() {
    // should happen before receiving buffers, and should only happen
    // once
    if (mMuxerStarted) {
    throw new IllegalStateException("output format already changed!");
    }
    MediaFormat newFormat = mEncoder.getOutputFormat();
    mVideoTrackIndex = mMuxer.addTrack(newFormat);
    mMuxer.start();
    mMuxerStarted = true;
    Log.i(TAG, "started media muxer, videoIndex=" + mVideoTrackIndex);
  }
  private void prepareEncoder() throws IOException {
    MediaFormat format = MediaFormat.createVideoFormat(MIME_TYPE, mWidth, mHeight);
    format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
    format.setInteger(MediaFormat.KEY_BIT_RATE, mBitRate);
    format.setInteger(MediaFormat.KEY_FRAME_RATE, FRAME_RATE);
    format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, IFRAME_INTERVAL);
    Log.d(TAG, "created video format: " + format);
    mEncoder = MediaCodec.createEncoderByType(MIME_TYPE);
    mEncoder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
    mSurface = mEncoder.createInputSurface();
    Log.d(TAG, "created input surface: " + mSurface);
    mEncoder.start();
  }
  private void release() {
    if (mEncoder != null) {
    mEncoder.stop();
    mEncoder.release();
    mEncoder = null;
    }
    if (mVirtualDisplay != null) {
    mVirtualDisplay.release();
    }
    if (mMediaProjection != null) {
    mMediaProjection.stop();
    }
    if (mMuxer != null) {
    mMuxer.stop();
    mMuxer.release();
    mMuxer = null;
    }
  }
}

该进程只实现了视频录制，调用该进程只需修改主进程中的onActivityResult方法。

MediaProjection似乎只有在屏幕发生变化时才传输，因此录屏推流的画面显得不够流畅