Video-Input
OpenCV processes both real-time image feed (in the case of a webcam) or prerecorded and hard disk drive stored files
Python
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captRefrnc = cv.VideoCapture(sourceReference)
refS = (
int(captRefrnc.get(cv.CAP_PROP_FRAME_WIDTH)),
int(captRefrnc.get(cv.CAP_PROP_FRAME_HEIGHT))
)
while True: # Show the image captured in the window and repeat
_, frameReference = captRefrnc.read()
if frameReference is None:
print(" < < < Game over! > > > ")
break
# ops ...
cv.imshow(WIN_RF, frameReference)
Video-Output
Python
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string::size_type pAt = source.find_last_of('.'); // Find extension point
const string NAME = source.substr(0, pAt) + argv[2][0] + ".avi"; // Form the new name with container
int ex = static_cast<int>(inputVideo.get(CAP_PROP_FOURCC)); // Get Codec Type- Int form
Size S = Size(
(int) inputVideo.get(CAP_PROP_FRAME_WIDTH), // Acquire input size
(int) inputVideo.get(CAP_PROP_FRAME_HEIGHT)
);
outputVideo.open(NAME, ex, inputVideo.get(CAP_PROP_FPS), S, true)
for(;;){
inputVideo >> src;
# ops...
outputVideo << res;
}
Using Kinect and other OpenNI compatible depth sensors
also Using Creative Senz3D and other Intel RealSense SDK compatible depth sensors
VideoCapture can retrieve the following data:
data given from depth generator:
CAP_OPENNI_DEPTH_MAP - depth values in mm (CV_16UC1)
CAP_OPENNI_POINT_CLOUD_MAP - XYZ in meters (CV_32FC3)
CAP_OPENNI_DISPARITY_MAP - disparity in pixels (CV_8UC1)
CAP_OPENNI_DISPARITY_MAP_32F - disparity in pixels (CV_32FC1)
CAP_OPENNI_VALID_DEPTH_MASK - mask of valid pixels (not occluded, not shaded etc.) (CV_8UC1)
data given from BGR image generator:
CAP_OPENNI_BGR_IMAGE - color image (CV_8UC3)
CAP_OPENNI_GRAY_IMAGE - gray image (CV_8UC1)
In order to get depth map from depth sensor use VideoCapture::operator >>, e. g. :
C++
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VideoCapture capture( CAP_OPENNI );
for(;;)
{
Mat depthMap;
capture >> depthMap;
if( waitKey( 30 ) >= 0 )
break;
}
For getting several data maps use VideoCapture::grab and VideoCapture::retrieve, e.g. :
C++
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VideoCapture capture(0); // or CAP_OPENNI
for(;;)
{
Mat depthMap;
Mat bgrImage;
capture.grab();
capture.retrieve( depthMap, CAP_OPENNI_DEPTH_MAP );
capture.retrieve( bgrImage, CAP_OPENNI_BGR_IMAGE );
if( waitKey( 30 ) >= 0 )
break;
}
For setting and getting some property of sensor` data generators use VideoCapture::set and VideoCapture::get methods respectively, e.g. :
C++
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VideoCapture capture( CAP_OPENNI );
capture.set( CAP_OPENNI_IMAGE_GENERATOR_OUTPUT_MODE, CAP_OPENNI_VGA_30HZ );
cout << "FPS " << capture.get( CAP_OPENNI_IMAGE_GENERATOR+CAP_PROP_FPS ) << endl;