National Instruments IEEE 1394 用户手册
Chapter 2
Basic Acquisition with NI-IMAQ for IEEE 1394 Cameras
© National Instruments Corporation
2-13
Grab
The low-level grab examples demonstrate how to perform a grab
acquisition using low-level function calls. The program sets up a
continuous acquisition into three internal buffers and starts the acquisition.
The main loop iterates continuously. In the main processing loop, the
program acquires an image and processes it. After the loop, the program
stops the acquisition, unconfigures the acquisition, and closes the session.
acquisition using low-level function calls. The program sets up a
continuous acquisition into three internal buffers and starts the acquisition.
The main loop iterates continuously. In the main processing loop, the
program acquires an image and processes it. After the loop, the program
stops the acquisition, unconfigures the acquisition, and closes the session.
Figure 2-6 illustrates the programming order of a low-level grab
acquisition.
acquisition.
Figure 2-6. Low-Level Grab Flowchart
Opens and Configures Camera
Starts Transferring Data from Camera
to Host Computer
to Host Computer
Executes User-Specific Image
Processing
Processing
Stops Transferring Data from Camera
to Host Computer
to Host Computer
Configures a Continuous Multiple-
Buffer Acquisition
Buffer Acquisition
Closes the Camera Session
Frees IEEE 1394 Bandwidth and Memory
Resources Used by the Acquisition
Resources Used by the Acquisition
Copies and Decodes Next Buffer
Number
Number
(Loop)
Loop until Stopped
Initialize
Configure
Start
Acquire
User-Specific Functions
Stop
Clear
Close