Android上实现视频录制

尽管Google的SDK文档写到了相关的，内容但是实在是太短小精悍了，因为需要写个简单的Demo，所以学习了一下。

现在，我们一起来看看，到底要怎么去写吧：

首先，我们肯定要用到摄像头，因此需要在Manifest文件中声明使用权限：

<uses-permission android:name="android.permission.CAMERA" />

如果还要使用一些硬件属性，那还要做额外的声明，例如：

<uses-feature android:name="android.hardware.camera"/>

<uses-feature:name="android.hardware.camera.autofocus"/>

当然，你还想要录制音频的话，还得加上：

<uses-permission android:name="android.permission.RECORD_AUDIO" />

当我们在录制的时候，通常都想要看到我们正在拍什么，这就需要预览，而预览需要在一个SurfaceView上实现，因此我们要添加一个控件：

<SurfaceView android:id="@+id/surface_camera" xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:layout_centerInParent="true"

android:layout_weight="1">

</SurfaceView>

然后，我们来实现这个Activity：

public class CustomVideoCamera extends Activity implements SurfaceHolder.Callback{

private static final String TAG = "CAMERA_TUTORIAL";

private SurfaceView surfaceView;

private SurfaceHolder surfaceHolder;

private Camera camera;

private boolean previewRunning;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.camera_surface);

surfaceView = (SurfaceView) findViewById(R.id.surface_camera);

surfaceHolder = surfaceView.getHolder();

surfaceHolder.addCallback(this);

surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

}

@Override

public void surfaceCreated(SurfaceHolder holder) {

camera = Camera.open();

if (camera != null){

Camera.Parameters params = camera.getParameters();

camera.setParameters(params);

}

else {

Toast.makeText(getApplicationContext(), "Camera not available!", Toast.LENGTH_LONG).show();

finish();

}

}

@Override

public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

if (previewRunning){

camera.stopPreview();

}

Camera.Parameters p = camera.getParameters();

p.setPreviewSize(width, height);

p.setPreviewFormat(PixelFormat.JPEG);

camera.setParameters(p);

try {

camera.setPreviewDisplay(holder);

camera.startPreview();

previewRunning = true;

}

catch (IOException e) {

Log.e(TAG,e.getMessage());

e.printStackTrace();

}

}

@Override

public void surfaceDestroyed(SurfaceHolder holder) {

camera.stopPreview();

previewRunning = false;

camera.release();

}

}

接着，我们就可以录制了：

private MediaRecorder mediaRecorder;

private final int maxDurationInMs = 20000;

private final long maxFileSizeInBytes = 500000;

private final int videoFramesPerSecond = 20;

public boolean startRecording(){

try {

camera.unlock();

mediaRecorder = new MediaRecorder();

mediaRecorder.setCamera(camera);

mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);

mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);

mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.DEFAULT);

mediaRecorder.setMaxDuration(maxDurationInMs);

tempFile = new File(getCacheDir(),cacheFileName);

mediaRecorder.setOutputFile(tempFile.getPath());

mediaRecorder.setVideoFrameRate(videoFramesPerSecond);

mediaRecorder.setVideoSize(surfaceView.getWidth(), surfaceView.getHeight());

mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT);

mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.DEFAULT);

mediaRecorder.setPreviewDisplay(surfaceHolder.getSurface());

mediaRecorder.setMaxFileSize(maxFileSizeInBytes);

mediaRecorder.prepare();

mediaRecorder.start();

return true;

} catch (IllegalStateException e) {

Log.e(TAG,e.getMessage());

e.printStackTrace();

return false;

} catch (IOException e) {

Log.e(TAG,e.getMessage());

e.printStackTrace();

return false;

}

}

停止拍摄，则：

public void stopRecording(){

mediaRecorder.stop();

camera.lock();

}

这样的话，通过编译之后，在Android OS 2.1 和 2.2上都能实现了，但在部分机器上会有些小问题，主要是预览上，看到app内的预览是另开线程做的，不知道是否会有改善？