问题
In android how to show preview surface before media recorder start. my app have video recording functionality,when i navigate to video recording fragment it display black screen,when i start recording using start button camera preview is display and recording start.
how to start preview before recording. i have added code that i used in onCreateView() of fragment-
surfaceHolder = mySurfaceView.getHolder();
camera = Camera.open();
if(camera!=null){
camera.setDisplayOrientation(90);
Camera.Parameters param;
param = camera.getParameters();
param.setPreviewFrameRate(20);
param.setPreviewSize(176, 144);
camera.setParameters(param);
camera.setPreviewDisplay(surfaceHolder);
}
mediaRecorder = new MediaRecorder();
camera.unlock();
mediaRecorder.setCamera(camera);
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
CamcorderProfile camcorderProfile_HQ = CamcorderProfile
.get(CamcorderProfile.QUALITY_HIGH);
mediaRecorder.setProfile(camcorderProfile_HQ);
String filePath = getOutputMediaFile(MEDIA_TYPE_VIDEO).getPath();
fileUri = getOutputMediaFileUri(MEDIA_TYPE_VIDEO);
mediaRecorder.setOutputFile(filePath);
and the code that i used on start button click-
mediaRecorder.setPreviewDisplay(surfaceHolder.getSurface());
mediaRecorder.prepare();
mediaRecorder.start();
so i am able to recode video by using above code,but not able to show preview before recording start. Please help me where i am missing.for that black screen is displayed before recoding video.
Thanks in advance.
回答1:
public void surfaceCreated(SurfaceHolder holder) {
if (mCamera != null) {
Parameters params = mCamera.getParameters();
mCamera.setParameters(params);
try {
//mCamera.setDisplayOrientation(90);
mCamera.setPreviewDisplay(holder);
} catch (IOException e) {
e.printStackTrace();
}
mCamera.startPreview();
}
}
If you implement SurfaceHolder.Callback, override the surfaceCreated method like this. This worked for me.
回答2:
I ran into the same problem. I looked it up and here's my Activity. It took me a bit of effort to make it not crash, so here's the final result. It displays the preview before the user clicks the REC button. (I am also displaying a countdown, but don't mind that). Notice also that there is too much work done on the main thread in this example (when clicking). There are a few things here that aren't best practices, but for a working example I think it's good enough.
import android.app.Activity;
import android.hardware.Camera;
import android.media.CamcorderProfile;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.File;
import java.io.IOException;
public class MainActivity extends Activity implements SurfaceHolder.Callback {
private static final String LOG_TAG = MainActivity.class.getCanonicalName();
Button myButton;
MediaRecorder mediaRecorder;
SurfaceHolder surfaceHolder;
boolean recording;
private TextView mTimer;
private Camera mCamera;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recording = false;
mediaRecorder = new MediaRecorder();
mCamera = Camera.open();
initMediaRecorder();
SurfaceView myVideoView = (SurfaceView) findViewById(R.id.videoview);
surfaceHolder = myVideoView.getHolder();
surfaceHolder.addCallback(this);
myButton = (Button) findViewById(R.id.mybutton);
myButton.setOnClickListener(myButtonOnClickListener);
mTimer = (TextView) findViewById(R.id.timer);
}
private Button.OnClickListener myButtonOnClickListener
= new Button.OnClickListener() {
@Override
public void onClick(final View arg0) {
CountDownTimer countDownTimer = new CountDownTimer(90 * 1000, 1000) {
@Override
public void onTick(long millisUntilFinished) {
mTimer.setText(String.valueOf(millisUntilFinished / 1000));
}
@Override
public void onFinish() {
onClick(arg0);
}
};
if (recording) {
// Stop recording and finish
try {
mediaRecorder.stop();
mediaRecorder.reset();
mediaRecorder.release();
finish();
} catch (Exception e) {
Log.e(LOG_TAG, "Failed to stop recorder", e);
}
} else {
// Release the camera and start recording
mCamera.release();
countDownTimer.start();
mediaRecorder.start();
recording = true;
myButton.setText("STOP");
}
}
};
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
if (mCamera != null) {
Camera.Parameters params = mCamera.getParameters();
mCamera.setParameters(params);
try {
mCamera.setPreviewDisplay(holder);
} catch (IOException e) {
e.printStackTrace();
}
mCamera.startPreview();
}
prepareMediaRecorder();
}
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
}
private void initMediaRecorder() {
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
CamcorderProfile camcorderProfile_HQ = CamcorderProfile.get(CamcorderProfile.QUALITY_CIF);
mediaRecorder.setProfile(camcorderProfile_HQ);
File file = new File(getExternalFilesDir(Environment.DIRECTORY_MOVIES), "myvideo.mp4");
if (file.exists()) {
file.delete();
}
mediaRecorder.setOutputFile(file.getAbsolutePath());
mediaRecorder.setMaxDuration(90000); // Set max duration 90 sec.
mediaRecorder.setMaxFileSize(15000000); // Set max file size 15M
}
private void prepareMediaRecorder() {
mediaRecorder.setPreviewDisplay(surfaceHolder.getSurface());
try {
mediaRecorder.prepare();
} catch (IllegalStateException | IOException e) {
Log.e(LOG_TAG, "Failed to prepare recorder", e);
}
}
}
来源：https://stackoverflow.com/questions/19176663/preview-display-in-android-media-recorder