camera startPreview failed

Question

I am creating a camera app but I have problems on startPreview, it sends me:

java.lang.RuntimeException: startPreview failed

here is my camera Activity:

public class CameraActivity extends Activity {

private Camera mCamera;
private CameraPreview  mPreview;
private Target_Frame targetFrame;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.camera_layout);




    mCamera=getCameraInstance();
    mPreview=new CameraPreview(this, mCamera);




    FrameLayout preview=(FrameLayout)findViewById(R.id.camera_preview);
    preview.addView(mPreview);

}




/** Check if this device has a camera only if not specified in the manifest */
public boolean checkCameraHardware(Context context) {
    if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
        // this device has a camera
        return true;
    } else {
        // no camera on this device
        return false;
    }
}

/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(){
    Camera c = null;
    try {
        c = Camera.open(); // attempt to get a Camera instance
    }
    catch (Exception e){
        // Camera is not available (in use or does not exist)
    }
    return c; // returns null if camera is unavailable
}

/**Check if the device has flash*/
public boolean checkFlash(Context context){
    if(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH)){
        //the device has flash
        return true;
    }else{
        //no flash
        return false;
    }

}




@Override
protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
    releaseCamera();
}




@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    releaseCamera();
}




@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();

    //Test if i have to put all this code like in onCreate
    if(mCamera!=null){
        return;
    }
    mCamera=getCameraInstance();

    if(mPreview!=null){
        return;
    }
    mPreview=new CameraPreview(this, mCamera);
    FrameLayout preview=(FrameLayout)findViewById(R.id.camera_preview);
    preview.addView(mPreview);


}


private void releaseCamera(){
    if (mCamera != null){
        mCamera.release();        // release the camera for other applications
        mCamera = null;
    }
}}

And here is my SurfaceView code:

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    private static final String TAG = "CameraPreview";
    private SurfaceHolder mHolder;
    private Camera mCamera;

    public CameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();

        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here
        Parameters parameters= mCamera.getParameters();
        parameters.setPreviewSize(w, h);
        mCamera.setParameters(parameters);

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}

And here is my error log:

12-01 13:17:01.135: E/AndroidRuntime(1161): FATAL EXCEPTION: main

12-01 13:17:01.135: E/AndroidRuntime(1161): java.lang.RuntimeException: startPreview

12-01 13:17:01.135: E/AndroidRuntime(1161):     at com.example.prueba.CameraPreview.surfaceCreated(CameraPreview.java:36) 

Answer 1

Is (w, h) a valid preview size for your camera?

You can use mCamera.getParameters().getSupportedPreviewSizes() to get all of the valid preview sizes.

Answer 2

Its late, but if someones looking for the answer

The variables w and h are not the optimal preview sizes . You can get optimal preview sizes using the function

public static Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio=(double)h / w;
        if (sizes == null) return null;

        Camera.Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        for (Camera.Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Camera.Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

and you can call the function using

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
..
size=getOptimalPreviewSize(parameters.getSupportedPreviewSizes(), w, h);
 parameters.setPreviewSize(size.getWidth(), size.getHeight());
..

}

Answer 3

I have solved deleting some lines in surfaceChanged

 public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.
        Log.d("Function", "surfaceChanged iniciado");
        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here


        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }

So the error must be in i one of these lines:

Parameters parameters= mCamera.getParameters();
    parameters.setPreviewSize(w, h);
    mCamera.setParameters(parameters);

Someone could explain me what was wrong in those lines?