Camera onPreviewFrame not called on XT910 - android-camera

Question

I have a problem with the camera of my MOTO XT910 android phone. I would like only to access to the camera's (frame)buffer but "onPreviewFrame" is never called. On my emulator, it works fine.
Thanks in advance,
My code is as below:
public class Store extends SurfaceView implements SurfaceHolder.Callback, PreviewCallback {
static {
System.loadLibrary("hello-jni");
}
public native void decode(Bitmap pTarget, byte[] pSource);
private Camera mCamera;
private byte[] mVideoSource;
private Bitmap mBackBuffer;
private Paint mPaint;
private Size lSize;
private static String TAG = Store.class.getCanonicalName();
public Store(Context context) {
super(context);
getHolder().addCallback(this);
setWillNotDraw(false);
}
public void surfaceCreated(SurfaceHolder holder) {
try {
mCamera = Camera.open();
mCamera.setDisplayOrientation(0);
mCamera.setPreviewDisplay(null);
mCamera.setPreviewCallbackWithBuffer(this);
Log.d(TAG,"surfaceCreated ok");
} catch (IOException eIOException) {
mCamera.release();
mCamera = null;
Log.d(TAG,"surfaceCreated failed");
throw new IllegalStateException();
}
}
public void surfaceChanged(SurfaceHolder pHolder, int pFormat, int pWidth, int pHeight) {
Log.d(TAG,"surfaceChanged in");
mCamera.stopPreview();
lSize = findBestResolution(pWidth, pHeight);
invalidate();
PixelFormat lPixelFormat = new PixelFormat();
PixelFormat.getPixelFormatInfo(mCamera.getParameters()
.getPreviewFormat(), lPixelFormat);
int lSourceSize = lSize.width * lSize.height * lPixelFormat.bitsPerPixel / 8;
mVideoSource = new byte[lSourceSize];
mBackBuffer = Bitmap.createBitmap(lSize.width, lSize.height,Bitmap.Config.ARGB_8888);
Camera.Parameters lParameters = mCamera.getParameters();
lParameters.setPreviewSize(lSize.width, lSize.height);
lParameters.setPreviewFormat(PixelFormat.YCbCr_420_SP);
mCamera.setParameters(lParameters);
mCamera.addCallbackBuffer(mVideoSource);
mCamera.startPreview();
Log.d(TAG,"surfaceChanged out");
}
private Size findBestResolution(int pWidth, int pHeight) {
List<Size> lSizes = mCamera.getParameters().getSupportedPreviewSizes();
Size lSelectedSize = mCamera.new Size(0, 0);
for (Size lSize : lSizes) {
if ((lSize.width <= pWidth) && (lSize.height <= pHeight)
&& (lSize.width >= lSelectedSize.width)
&& (lSize.height >= lSelectedSize.height)) {
lSelectedSize = lSize;
}
}
if ((lSelectedSize.width == 0) || (lSelectedSize.height == 0)) {
lSelectedSize = lSizes.get(0);
}
return lSelectedSize;
}
public void surfaceDestroyed(SurfaceHolder holder) {
if (mCamera != null) {
Log.d(TAG,"surfaceDestroyed");
mCamera.stopPreview();
mCamera.release();
mCamera = null;
mVideoSource = null;
mBackBuffer = null;
}
}
public void onPreviewFrame(byte[] pData, Camera pCamera) {
Log.d(TAG,"onPreviewFrame");
decode(mBackBuffer, pData);
invalidate();
}
#Override
protected void onDraw(Canvas pCanvas) {
Log.d(TAG,"onDraw in");
if (mCamera != null) {
Paint paint = new Paint();
paint.setColor(Color.YELLOW);
String text = String.format("%dx%d", lSize.width, lSize.height);
pCanvas.drawText(text, 10, 10, paint);
pCanvas.drawLine(0, 0, 100, 100, paint);
pCanvas.drawLine(20, 0, 0, 20, paint);
pCanvas.drawBitmap(mBackBuffer, 0, 0, mPaint);
mCamera.addCallbackBuffer(mVideoSource);
Log.d(TAG,"onDraw out");
}
}
}

Answer 1

First I assume you didn't get an exception and that the camera parameters you used (PixelFormat.YCbCr_420_SP) is supported by your camera.
To fix the problem you should try to add mCamera.setPreviewDisplay(view);
with a surface view and not with null. Unfortunately according to android guys the preview should not start without a surface view :
Unfortunately, there's no way to get preview frames without having a SurfaceView to display them, if you're targeting pre-3.0 devices. On 3.0 and later, you can use the Camera#setPreviewTexture() method to send preview data to a GPU texture. Even if just want to use the YUV data instead of RGB data in the GPU, this would allow you to stream without a mandatory UI element; just ignore the SurfaceTexture entirely.
If you stick with your current approach, you'll unfortunately find that your app will not function properly on many devices; there are several that follow the API's restriction on having to have setPreviewDisplay() or setPreviewTexture() set before preview data will be sent.
See the full bug report here : http://code.google.com/p/android/issues/detail?id=28238
However as I said in this bug report it can work without a surface view, but there is no guarantee.