Lập trình Android: ứng dụng quay Video docx

Trung tâm Tin học – ĐH KHTN
Quay Video
Ở hầu hết các điện thoại có hệ điều hành Android đều có hỗ trợ Camera. Và trong bài
viết này mình sẽ xây dựng 1 chương trình xử dụng Camera của thiết bị để quay video.
Các bước làm nên chương trình như sau:
1/ Tạo Project :
Project name: RecordVideo
Build Target: Android 2.3.3
Application name: RecordVideo
Package name: com.dac.RecordVideo
Create Activity: MainActivity
2/ Trong file main.xml các bạn thiết kế như sau:
<?xml version="1.0" encoding="utf-8"?>
<! This file is /res/layout-land/main.xml >
<LinearLayout xmlns:android=" /> android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="horizontal" >
<LinearLayout
android:orientation="vertical" android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button android:id="@+id/initBtn"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Initialize Recorder" android:onClick="doClick"
android:enabled="false" />
<Button android:id="@+id/beginBtn"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Begin Recording" android:onClick="doClick"
android:enabled="false" />
<Button android:id="@+id/stopBtn"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Stop Recording" android:onClick="doClick" />
<Button android:id="@+id/playRecordingBtn"

android:layout_width="wrap_content" android:layout_height="wrap_content"
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Trung tâm Tin học – ĐH KHTN
android:text="Play Recording" android:onClick="doClick" />
<Button android:id="@+id/stopPlayingRecordingBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Stop Playing" android:onClick="doClick" />
</LinearLayout>
<LinearLayout android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="fill_parent" >
<TextView android:id="@+id/recording" android:text=" "
android:textColor="#FF0000"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<VideoView android:id="@+id/videoView"
android:layout_width="250dip" android:layout_height="200dip" />
</LinearLayout>
</LinearLayout>
3/ Trong file MainActivity.java:
package com.dac.RecordVideo;
import java.io.File;
import java.io.IOException;
import android.app.Activity;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.media.MediaRecorder.OnErrorListener;
import android.media.MediaRecorder.OnInfoListener;
import android.os.Bundle;
import android.os.Environment;

import android.util.Log;
import android.view.SurfaceHolder;
import android.view.View;
import android.widget.Button;
import android.widget.MediaController;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.VideoView;
public class MainActivity extends Activity implements
SurfaceHolder.Callback, OnInfoListener, OnErrorListener {
private static final String TAG = "RecordVideo";
private MediaRecorder mRecorder = null;
private String mOutputFileName;
private VideoView mVideoView = null;
private SurfaceHolder mHolder = null;
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Trung tâm Tin học – ĐH KHTN
private Button mInitBtn = null;
private Button mStartBtn = null;
private Button mStopBtn = null;
private Button mPlayBtn = null;
private Button mStopPlayBtn = null;
private Camera mCamera = null;
private TextView mRecordingMsg = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.v(TAG, "in onCreate");
setContentView(R.layout.main);

mInitBtn = (Button) findViewById(R.id.initBtn);
mStartBtn = (Button) findViewById(R.id.beginBtn);
mStopBtn = (Button) findViewById(R.id.stopBtn);
mPlayBtn = (Button) findViewById(R.id.playRecordingBtn);
mStopPlayBtn = (Button) findViewById(R.id.stopPlayingRecordingBtn);
mRecordingMsg = (TextView) findViewById(R.id.recording);
mVideoView = (VideoView)this.findViewById(R.id.videoView);
}
private boolean initCamera() {
try {
mCamera = Camera.open();
Camera.Parameters camParams = mCamera.getParameters();
mCamera.lock();
mHolder = mVideoView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
catch(RuntimeException re) {
Log.v(TAG, "Could not initialize the Camera");
re.printStackTrace();
return false;
}
return true;
}
private void releaseRecorder() {
if(mRecorder != null) {
mRecorder.release();
mRecorder = null;
}
}

private void releaseCamera() {
if(mCamera != null) {
try {
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Trung tâm Tin học – ĐH KHTN
mCamera.reconnect();
} catch (IOException e) {
e.printStackTrace();
}
mCamera.release();
mCamera = null;
}
}
@Override
protected void onResume() {
Log.v(TAG, "in onResume");
super.onResume();
mInitBtn.setEnabled(false);
mStartBtn.setEnabled(false);
mStopBtn.setEnabled(false);
mPlayBtn.setEnabled(false);
mStopPlayBtn.setEnabled(false);
if(!initCamera())
finish();
}
@Override
protected void onPause() {
Log.v(TAG, "in onPause");
super.onPause();
releaseRecorder();

releaseCamera();
}
@Override
protected void onDestroy() {
Log.v(TAG, "in onDestroy");
super.onDestroy();
}
public void doClick(View view) {
switch(view.getId()) {
case R.id.initBtn:
initRecorder();
break;
case R.id.beginBtn:
beginRecording();
break;
case R.id.stopBtn:
stopRecording();
break;
case R.id.playRecordingBtn:
playRecording();
break;
case R.id.stopPlayingRecordingBtn:
stopPlayingRecording();
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Trung tâm Tin học – ĐH KHTN
break;
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {

Log.v(TAG, "in surfaceCreated");
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (IOException e) {
Log.v(TAG, "Could not start the preview");
e.printStackTrace();
}
mInitBtn.setEnabled(true);
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.v(TAG, "in surfaceDestroyed");
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
Log.v(TAG, "surfaceChanged: Width x Height = " + width + "x" + height);
}
private void initRecorder() {
if(mRecorder != null) return;
mOutputFileName = Environment.getExternalStorageDirectory() +
"/videooutput.mp4";
File outFile = new File(mOutputFileName);
if(outFile.exists()) {
outFile.delete();
}
try {
mCamera.stopPreview();
mCamera.unlock();

mRecorder = new MediaRecorder();
mRecorder.setCamera(mCamera);
mRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
mRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
mRecorder.setVideoSize(176, 144);
mRecorder.setVideoFrameRate(15);
mRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
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Trung tâm Tin học – ĐH KHTN
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mRecorder.setMaxDuration(7000); // limit to 7 seconds
mRecorder.setPreviewDisplay(mHolder.getSurface());
mRecorder.setOutputFile(mOutputFileName);
mRecorder.prepare();
Log.v(TAG, "MediaRecorder initialized");
mInitBtn.setEnabled(false);
mStartBtn.setEnabled(true);
}
catch(Exception e) {
Log.v(TAG, "MediaRecorder failed to initialize");
e.printStackTrace();
}
}
private void beginRecording() {
mRecorder.setOnInfoListener(this);
mRecorder.setOnErrorListener(this);
mRecorder.start();
mRecordingMsg.setText("RECORDING");
mStartBtn.setEnabled(false);

mStopBtn.setEnabled(true);
}
private void stopRecording() {
if (mRecorder != null) {
mRecorder.setOnErrorListener(null);
mRecorder.setOnInfoListener(null);
try {
mRecorder.stop();
}
catch(IllegalStateException e) {
Log.e(TAG, "Got IllegalStateException in stopRecording");
}
releaseRecorder();
mRecordingMsg.setText("");
releaseCamera();
mStartBtn.setEnabled(false);
mStopBtn.setEnabled(false);
mPlayBtn.setEnabled(true);
}
}
private void playRecording() {
MediaController mc = new MediaController(this );
mVideoView.setMediaController(mc);
mVideoView.setVideoPath(mOutputFileName);
mVideoView.start();
mStopPlayBtn.setEnabled(true);
}
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Trung tâm Tin học – ĐH KHTN
private void stopPlayingRecording() {

mVideoView.stopPlayback();
}
@Override
public void onInfo(MediaRecorder mr, int what, int extra) {
Log.i(TAG, "got a recording event");
if(what == MediaRecorder.MEDIA_RECORDER_INFO_MAX_DURATION_REACHED) {
Log.i(TAG, " max duration reached");
stopRecording();
Toast.makeText(this, "Recording limit has been reached. Stopping
the recording",
Toast.LENGTH_SHORT).show();
}
}
@Override
public void onError(MediaRecorder mr, int what, int extra) {
Log.e(TAG, "got a recording error");
stopRecording();
Toast.makeText(this, "Recording error has occurred. Stopping the
recording",
Toast.LENGTH_SHORT).show();
}
}
Và trong phần AndroidManifest.xml các bạn thêm các Permission vào ứng dụng:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=" /> package="com.dac.Recordvideo"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".MainActivity"
android:label="@string/app_name"

android:screenOrientation="landscape">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="4" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
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Trung tâm Tin học – ĐH KHTN
<uses-permission android:name="android.permission.CAMERA"/>
</manifest>
Cuối cùng các bạn debug ứng dụng (lưu ý ứng dụng chỉ chạy video trên máy thật) và
các bạn bấm Ctrl+F11 để chuyển qua màn hình ngang :
Mọi ý kiến đóng góp các bạn vui lòng gữi bài viết về forum :
. Rất mong nhận được sự phản hồi của các bạn.
Lập trình Android – Page 8