浅析Android录屏 MediaRecorder

时间：2020-10-05 21:31:55|栏目：Android代码|点击：次

MediaRecorder类介绍：

MediaRecorder类是Android sdk提供的一个专门用于音视频录制，一般利用手机麦克风采集音频，摄像头采集图片信息。

Android录屏的三种方案

1、adb shell命令screenrecord
2、MediaRecorder, MediaProjection
3、MediaCodec和MediaMuxer, MediaProjection ,

一、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 1280x720 --bit-rate 6000000 --time-limit 30 /sdcard/demo.mp4
--size 指定视频分辨率，根据手机情况决定
--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；

并不是所以手机都执行screenrecord命令，部分手机不识别。
我在几款华为手机就没执行成功报错：
/system/bin/sh: screenrecord: inaccessible or not found

二、 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。

这里先整体说一下屏幕录制的流程，不然看起来费劲。

1、通过startActivityForResult(Intent intent)判断是否录屏授权的Activity

其中intent对象就需要MediaProjectionManager.createScreenCaptureIntent();获取

2、在onActivityResult回调方法中做具体录屏工作

比如：创建MediaRecorder，设置MP4文件路径
创建VirtualDisplay，设置屏幕相关参数
如果不在onActivityResult回调中执行会有问题。

3、开始录屏

MediaRecorder.start()

4、停止录屏

MediaRecorder.reset();
MediaRecorder.release();

录屏过程用到录音权限和数据读写权限。

三、MediaCodec和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。

这个录屏的方式和MediaRecorder是类似的，只是流程第二部有点不同，这里不做介绍。

详情可以参考：https://www.jb51.net/article/183324.htm

四、MediaRecorder项目示例的主要代码

这里只做了录制和停止录制，没有做相关适配，比如横竖屏切换后尺寸变化。

简单效果：

在这里插入图片描述

生成的MP4文件会在sdcard目录下，并且以录屏时间为文件名。

1、MainActivity

package com.liwenzhi.screen;
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.media.projection.MediaProjection;
import android.media.projection.MediaProjectionManager;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.io.File;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
 String TAG = "MainActivity";
 MediaProjectionManager mProjectionManager;
 MediaRecordService mediaRecord;
 int displayWidth = 1280;
 int displayHeight = 1920;
 Button btn_start_record;
 Button btn_stop_record;
 TextView tv_time;
 int REQUEST_CODE_PERMISSIONS = 99;
 int REQUEST_CODE_SCREEN = 100;
 //录音权限和数据读写权限
 String[] permissions = new String[]{Manifest.permission.RECORD_AUDIO, Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
 boolean mPassPermissions = true;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 initView();
 initData();
 initEvent();
 }
 private void initView() {
 btn_start_record = findViewById(R.id.btn_start_record);
 btn_stop_record = findViewById(R.id.btn_stop_record);
 tv_time = findViewById(R.id.tv_time);
 }
 private void initData() {
 //权限申请
 //逐个判断你要的权限是否已经通过
 judgePermissions();
 if (!mPassPermissions) {
  ActivityCompat.requestPermissions(this, permissions, REQUEST_CODE_PERMISSIONS);
 }
 }
 private void initEvent() {
 btn_start_record.setOnClickListener(this);
 btn_stop_record.setOnClickListener(this);
 }
 // 申请权限后的回调
 // 1、录音和读写
 // 2、录屏startActivityForResult后的回调
 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
 super.onActivityResult(requestCode, resultCode, data);
 //录音和读写权限
 if (requestCode == REQUEST_CODE_PERMISSIONS) {
  if (resultCode != Activity.RESULT_OK) {
  mPassPermissions = false;
  }
 } else
  // 录屏权限
  if (requestCode == REQUEST_CODE_SCREEN) {
  if (resultCode == Activity.RESULT_OK) {
   try {
   // mediaProjection 如果不在权限申请中回调，获取到的对象为空
   MediaProjection mediaProjection = mProjectionManager.getMediaProjection(resultCode, data);
   if (mediaProjection == null) {
    Log.e(TAG, "media projection is null");
    return;
   }
   File file = new File("/sdcard/" + MyTimeUtils.getTimeString("yyyy-MM-dd_HH:mm:ss") + ".mp4"); //录屏生成文件
   if (!file.exists()) {
    file.createNewFile();
   }
   mediaRecord = new MediaRecordService(displayWidth, displayHeight, 6000000, 1,
    mediaProjection, file.getAbsolutePath());
   mediaRecord.start();
   second = 0;
   mHandler.sendEmptyMessageDelayed(10, 1000);
   } catch (Exception e) {
   e.printStackTrace();
   }
  } else {
   Toast.makeText(MainActivity.this, "录屏失败", Toast.LENGTH_LONG).show();
  }
  }
 }
 @Override
 public void onBackPressed() {
 //super.onBackPressed();
 }
 @Override
 public void onClick(View v) {
 switch (v.getId()) {
  case R.id.btn_start_record:
  startRecord();
  break;
  case R.id.btn_stop_record:
  stopRecord();
  break;
 }
 }
 // 开始录屏
 private void startRecord() {
 judgePermissions();
 if (!mPassPermissions) {
  Toast.makeText(this, "基础权限没通过！", Toast.LENGTH_LONG).show();
  return;
 }
 mProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
 if (mProjectionManager != null) {
  Intent intent = mProjectionManager.createScreenCaptureIntent();
  PackageManager packageManager = getPackageManager();
  if (packageManager.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY) != null) {
  //存在录屏授权的Activity
  startActivityForResult(intent, REQUEST_CODE_SCREEN);
  } else {
  Toast.makeText(this, "没有录屏权限！", Toast.LENGTH_LONG).show();
  }
 }
 }
 // 停止录屏
 private void stopRecord() {
 mediaRecord.release();
 mHandler.removeMessages(10);
 }
 int second;
 // 计算时间
 Handler mHandler = new Handler() {
 @Override
 public void handleMessage(Message msg) {
  super.handleMessage(msg);
  switch (msg.what) {
  case 10:
   second++;
   tv_time.setText(second + "");
   mHandler.sendEmptyMessageDelayed(10, 1000);
   break;
  }
 }
 };
 //判断每个权限是否通过
 private void judgePermissions() {
 boolean permission = true;
 for (int i = 0; i < permissions.length; i++) {
  if (ContextCompat.checkSelfPermission(this, permissions[i]) != PackageManager.PERMISSION_GRANTED) {
  // 未授予的权限
  permission = false;
  }
 }
 mPassPermissions = permission;
 }
}

2、MediaRecordService

package com.liwenzhi.screen;
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");
 }
}

3、MyTimeUtils

package com.liwenzhi.screen;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
 * a Utils for time
 * <p>
 * identify the following letter: ："yyyy-MM-dd DD HH:mm:ss SSS"
 * * method1： long getTimeLong()
 * * method2： int getTimeInt(String filter)
 * * method3： String getTimeString()
 * * method4： String getTimeString(long time)
 * * method5： String getTimeString(long time, String filter)
 * * method6： String getTimeString( String filter)
 */
public class MyTimeUtils {
 public static long getTimeLong() {
 return System.currentTimeMillis();
 }
 public static int getTimeInt(String filter) {
 SimpleDateFormat format = new SimpleDateFormat(filter);
 String time = format.format(new Date());
 return Integer.parseInt(time);
 }
 public static final String getTimeString() {
 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 return format.format(new Date(getTimeLong()));
 }
 public static final String getTimeString(long time) {
 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 return format.format(new Date(time));
 }
 public static final String getTimeString(long time, String filter) {
 SimpleDateFormat format = new SimpleDateFormat(filter);
 return format.format(new Date(time));
 }
 public static final String getTimeString(String filter) {
 SimpleDateFormat format = new SimpleDateFormat(filter);
 return format.format(new Date(getTimeLong()));
 }
 public static Long getTimeLong(String filter, String date) {
 try {
  SimpleDateFormat format = new SimpleDateFormat(filter);
  Date dateTime = format.parse(date);
  return dateTime.getTime();
 } catch (Exception e) {
  e.printStackTrace();
 }
 return 0L;
 }
}

测试apk和项目源码下载：

http://xiazai.jb51.net/202003/yuanma/RecordMedia_jb51.rar

这个项目只是简单录屏，如果要做得好，
最好是正在通知栏/悬浮框里面控制停止，
并且可以按退出键回到主界面，
要用到服务来控制录屏屏幕的开始和停止。

共勉：时间总会过去，多做一下有意义的事情。

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