Android preview processing while video recording

Question

I am using Android development (SDK 2.2) and I would like to make a video recording with mediaRecorder and, at the same time, do some process on each preview frame.

I record video with MediaRecorder in a project, in an other I use the onPreviewFrame(byte[] data, Camera camera) (from PreviewCallback) for processing preview pictures.

I've tried to create a Camera and use it with mediaRecorder (setCamera function) but it doesn't work.

Is it possible to do both in the same time?

Actually I don't understand how to link two things?

My code :

package ch.fraise;

import java.io.IOException;
import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraActivity extends Activity implements SurfaceHolder.Callback,
    Camera.AutoFocusCallback {

private SurfaceView preview;
private SurfaceHolder previewHolder;

private MediaRecorder mRecorder;
private Camera mCamera;
private boolean mPreviewRunning = false;
private boolean mCaptureFrame = false;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.e("", "Begin onCreate");
    setContentView(R.layout.main);

    preview = (SurfaceView) findViewById(R.id.surfaceView1);
    previewHolder = preview.getHolder();
    previewHolder.addCallback(this);
    previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    mRecorder = new MediaRecorder();
}

@Override
public void onResume() {
    super.onResume();
}

@Override
public void onPause() {
    super.onPause();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.capture_menu, menu);
    return true;
}

public void startRecording() {
    Log.e("", "Begin StartRecording");
    mCaptureFrame = true;
    mRecorder.start();
}

public void stopRecording() {
    Log.e("", "Begin StopChange");
    mRecorder.stop();
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle item selection
    switch (item.getItemId()) {
    case R.id.startRecording:
        startRecording();
        return true;
    case R.id.stopRecording:
        stopRecording();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    Log.e("", "Begin surfaceDestroy");
    mCamera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCamera.stopPreview();
    mPreviewRunning = false;
    mCamera.release();

    mRecorder.reset();
    mRecorder.release();
}

@Override
public void onAutoFocus(boolean success, Camera camera) {
    // TODO Auto-generated method stub

}

/*
 * PreviewCallback()
 * 
 * this callback captures the preview at every frame and puts it in a byte
 * buffer. we will evaluate if this is a frame that we want to process, and
 * if so, we will send it to an asynchronous thread that will process it to
 * an ARGB Bitmap and POST it to the server
 */
PreviewCallback previewCallback = new PreviewCallback() {
    public void onPreviewFrame(byte[] data, Camera camera) {
        Log.e("", "onPreviewFrame pass");
        if (mCaptureFrame) {
            mCaptureFrame = false;
            // new FrameHandler().execute(data);
        }
    }
};

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
        int height) {
    Log.e("", "Begin SurfaceChange");

    mRecorder.reset();
    mRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
    mRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
    mRecorder.setOutputFile("/sdcard/videotest2.mp4");
    mRecorder.setVideoFrameRate(30);

    mRecorder.setPreviewDisplay(previewHolder.getSurface());
    try {
        mRecorder.prepare();
    } catch (IllegalStateException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    if (mPreviewRunning)
        mCamera.stopPreview();

    Camera.Parameters p = mCamera.getParameters();
    // p.setPreviewSize(width, height);
    mCamera.setParameters(p);

    try {
        mCamera.setPreviewDisplay(holder);
    } catch (IOException e) {
        e.printStackTrace();
    }

    mCamera.setPreviewCallback(previewCallback);

    mCamera.startPreview();
    mPreviewRunning = true;

}

}

and the permissions in the XML file :

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

Answer 1

Eureka! The trick is to attach your PreviewCallback in the surfaceChanged(...) SurfaceHolder.Callback! After doing this, you'll continue to get preview frame data after a MediaRecorder is running!

For example:

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    mCamera.setPreviewCallback(new PreviewCallback() {
            public void onPreviewFrame(byte[] _data, Camera _camera) {
                Log.d("onPreviewFrame-surfaceChanged",String.format("Got %d bytes of camera data", _data.length));
            }
        });

}