OpenLvVision_OpenCv.lvlib:VideoCapture.lvclass:VideoCapture Grab.vi

Grabs the next frame from video file or capturing device.

The method/function grabs the next frame from video file or camera and returns true (non-zero) in the case of success.

The primary use of the function is in multi-camera environments, especially when the cameras do not have hardware synchronization. That is, you call VideoCapture::grab() for each camera and after that call the slower method VideoCapture::retrieve() to decode and get frame from each camera. This way the overhead on demosaicing or motion jpeg decompression etc. is eliminated and the retrieved frames from different cameras will be closer in time.

Also, when a connected camera is multi-head (for example, a stereo camera or a Kinect device), the correct way of retrieving data from it is to call VideoCapture::grab() first and then call VideoCapture::retrieve() one or more times with different values of the channel parameter.

For detailed information, please refer to the OpenCV documentation

OpenLvVision_OpenCv.lvlib:VideoCapture.lvclass:VideoCapture Grab.vi

cerrcodeclst

error in (no error)

The error in cluster can accept error information wired from VIs previously called. Use this information to decide if any functionality should be bypassed in the event of errors from other VIs.

The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    cbool

    		status

    The status boolean is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    ci32

    		code

    The code input identifies the error or warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    cstr

    		source

    The source string describes the origin of the error or warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

cOpenLvVision__OpenCv_lvlib_VideoCapturelvclass

VideoCapture in

ierrcodeclst

error out

The error out cluster passes error or warning information out of a VI to be used by other VIs.

The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    ibool

    		status

    The status boolean is either TRUE (X) for an error, or FALSE (checkmark) for no error or a warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    ii32

    		code

    The code input identifies the error or warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

    istr

    		source

    The source string describes the origin of the error or warning.

    The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

iOpenLvVision__OpenCv_lvlib_VideoCapturelvclass

VideoCapture out

ibool

Success