Class Capture

Represents a video capture stream.

Inheritance

Object

Capture

Namespace: OpenCV.Net

Assembly: OpenCV.Net.dll

Syntax

public sealed class Capture : SafeHandleZeroOrMinusOneIsInvalid

Properties

CaptureDomain

Gets the capture back end used for image acquisition.

Declaration

public CaptureDomain CaptureDomain { get; }

Property Value

Type	Description
CaptureDomain

Methods

CreateCameraCapture(Int32)

Initializes capturing a video from a camera.

Declaration

public static Capture CreateCameraCapture(int index)

Parameters

Type	Name	Description
Int32	index	Index of the camera to be used. If there is only one camera or it does not matter what camera is used -1 may be passed.

Returns

Type	Description
Capture	A newly created Capture instance representing image acquisition from a camera.

CreateCameraCapture(Int32, CaptureDomain)

Initializes capturing a video from a camera using the specified domain.

Declaration

public static Capture CreateCameraCapture(int index, CaptureDomain domain)

Parameters

Type	Name	Description
Int32	index	Index of the camera to be used. If there is only one camera or it does not matter what camera is used -1 may be passed.
CaptureDomain	domain	The capture domain used to indicate what kind of camera source should be acquired.

Returns

Type	Description
Capture	A newly created Capture instance representing image acquisition from a camera.

CreateFileCapture(String)

Initializes capturing a video from the specified file. Which codecs and file formats are supported depends on the back end library.

Declaration

public static Capture CreateFileCapture(string fileName)

Parameters

Type	Name	Description
String	fileName	The path to the video file.

Returns

Type	Description
Capture	A newly created Capture instance representing image acquisition from a video file.

GetProperty(CaptureProperty)

Gets video capture properties.

Declaration

public double GetProperty(CaptureProperty propertyId)

Parameters

Type	Name	Description
CaptureProperty	propertyId	The property identifier as specified by CaptureProperty.

Returns

Type	Description
Double	The value of the specified property.

GrabFrame()

Grabs a frame from a camera or file. The grabbed frame is stored internally and can be retrieved by calling RetrieveFrame(Int32).

Declaration

public bool GrabFrame()

Returns

Type	Description
Boolean	A value indicating whether a new frame was grabbed.

QueryFrame()

Grabs and returns a frame from a camera or file.

Declaration

public IplImage QueryFrame()

Returns

Type	Description
IplImage	The reference to the newly captured frame. The returned image should not be released or modified by the user. In the event of an error, the return value may be null.

ReleaseHandle()

Executes the code required to free the native Capture handle.

Declaration

protected override bool ReleaseHandle()

Returns

Type	Description
Boolean	true if the handle is released successfully; otherwise, in the event of a catastrophic failure, false.

RetrieveFrame(Int32)

Gets the image grabbed with GrabFrame().

Declaration

public IplImage RetrieveFrame(int streamIdx = 0)

Parameters

Type	Name	Description
Int32	streamIdx	The index of the stream from which to retrieve the frame.

Returns

Type	Description
IplImage	The reference to the newly captured frame. The returned image should not be released or modified by the user. In the event of an error, the return value may be null.

SetProperty(CaptureProperty, Double)

Sets video capture properties.

Declaration

public void SetProperty(CaptureProperty propertyId, double value)

Parameters

Type	Name	Description
CaptureProperty	propertyId	The property identifier as specified by CaptureProperty.
Double	value	The new value of the specified property.