_controller = CameraController(
      camera,
      ResolutionPreset.high,
      enableAudio: false,
      imageFormatGroup: Platform.isAndroid
          ? ImageFormatGroup.nv21
          : ImageFormatGroup.bgra8888,
    );
   _controller?.startImageStream(_processCameraImage);
   

_processCameraImage(InputImage image){
if (_controller == null) return null;
    InputImageRotation? rotation;
    if (Platform.isIOS) {
      rotation = InputImageRotationValue.fromRawValue(sensorOrientation);
    } else if (Platform.isAndroid) {
      var rotationCompensation =
          _orientations[_controller!.value.deviceOrientation];
      if (rotationCompensation == null) return null;
      if (camera.lensDirection == CameraLensDirection.front) {
        rotationCompensation = (sensorOrientation + rotationCompensation) % 360;
      } else {
        rotationCompensation =
            (sensorOrientation - rotationCompensation + 360) % 360;
      }
      rotation = InputImageRotationValue.fromRawValue(rotationCompensation);
    }
    if (rotation == null) return null;
    final format = InputImageFormatValue.fromRawValue(image.format.raw);
    print(format); => return format should return as ImageFormatGroup.nv21InputImageFormat.nv21
}