Class VideoCapture

Video capturing class

Inheritance

System.Object

DisposableObject

DisposableCvObject

VideoCapture

Implements

ICvPtrHolder

Inherited Members

DisposableCvObject.ptr

DisposableCvObject.CvPtr

DisposableObject.DataHandle

DisposableObject.IsDisposed

DisposableObject.IsEnabledDispose

DisposableObject.AllocatedMemory

DisposableObject.AllocatedMemorySize

DisposableObject.Dispose()

DisposableObject.Dispose(Boolean)

DisposableObject.DisposeManaged()

DisposableObject.AllocGCHandle(Object)

DisposableObject.AllocMemory(Int32)

DisposableObject.NotifyMemoryPressure(Int64)

DisposableObject.ThrowIfDisposed()

Namespace: OpenCvSharp

Assembly: OpenCvSharp.dll

Syntax

public class VideoCapture : DisposableCvObject, ICvPtrHolder

Constructors

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VideoCapture()

Initializes empty capture. To use this, you should call Open.

Declaration

public VideoCapture()

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VideoCapture(IntPtr)

Initializes from native pointer

Declaration

protected VideoCapture(IntPtr ptr)

Parameters

Type	Name	Description
IntPtr	ptr	CvCapture*

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VideoCapture(Int32, VideoCaptureAPIs)

Opens a camera for video capturing

Declaration

public VideoCapture(int index, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.Int32	index	id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
VideoCaptureAPIs	apiPreference	preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.

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VideoCapture(Int32, VideoCaptureAPIs, VideoCapturePara)

Opens a camera for video capturing with API Preference and parameters

Declaration

public VideoCapture(int index, VideoCaptureAPIs apiPreference, VideoCapturePara prms)

Parameters

Type	Name	Description
System.Int32	index	id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
VideoCaptureAPIs	apiPreference	preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.
VideoCapturePara	prms	Parameters of VideoCapture for hardware acceleration

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VideoCapture(Int32, VideoCaptureAPIs, Int32[])

Opens a camera for video capturing with API Preference and parameters

Declaration

public VideoCapture(int index, VideoCaptureAPIs apiPreference, int[] prms)

Parameters

Type	Name	Description
System.Int32	index	id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
VideoCaptureAPIs	apiPreference	preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.
System.Int32[]	prms	The `params` parameter allows to specify extra parameters encoded as pairs `(paramId_1, paramValue_1, paramId_2, paramValue_2, ...)`. See cv::VideoCaptureProperties

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VideoCapture(String, VideoCaptureAPIs)

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Declaration

public VideoCapture(string fileName, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.String	fileName	it can be: name of video file (e.g. `video.avi`) or image sequence (e.g. `img_%02d.jpg`, which will read samples like `img_00.jpg, img_01.jpg, img_02.jpg, ...`) or URL of video stream (e.g. `protocol://host:port/script_name?script_params\|auth`). Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.
VideoCaptureAPIs	apiPreference	apiPreference preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.

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VideoCapture(String, VideoCaptureAPIs, VideoCapturePara)

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Declaration

public VideoCapture(string fileName, VideoCaptureAPIs apiPreference, VideoCapturePara prms)

Parameters

Type	Name	Description
System.String	fileName	it can be: name of video file (e.g. `video.avi`) or image sequence (e.g. `img_%02d.jpg`, which will read samples like `img_00.jpg, img_01.jpg, img_02.jpg, ...`) or URL of video stream (e.g. `protocol://host:port/script_name?script_params\|auth`). Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.
VideoCaptureAPIs	apiPreference	apiPreference preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.
VideoCapturePara	prms	Parameters of VideoCature for hardware acceleration

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VideoCapture(String, VideoCaptureAPIs, Int32[])

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Declaration

public VideoCapture(string fileName, VideoCaptureAPIs apiPreference, int[] prms)

Parameters

Type	Name	Description
System.String	fileName	it can be: name of video file (eg. `video.avi`) or image sequence (eg. `img_%02d.jpg`, which will read samples like `img_00.jpg, img_01.jpg, img_02.jpg, ...`) or URL of video stream (eg. `protocol://host:port/script_name?script_params\|auth`). Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.
VideoCaptureAPIs	apiPreference	apiPreference preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.
System.Int32[]	prms	The `params` parameter allows to specify extra parameters encoded as pairs `(paramId_1, paramValue_1, paramId_2, paramValue_2, ...)`. See cv::VideoCaptureProperties

Properties

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AutoExposure

exposure control done by camera, user can adjust refernce level using this feature [CV_CAP_PROP_AUTO_EXPOSURE]

Declaration

public double AutoExposure { get; set; }

Property Value

Type	Description
System.Double

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AutoFocus

Declaration

public bool AutoFocus { get; set; }

Property Value

Type	Description
System.Boolean

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BackLight

Declaration

public double BackLight { get; set; }

Property Value

Type	Description
System.Double

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Brightness

Gets or sets brightness of image (only for cameras)

Declaration

public double Brightness { get; set; }

Property Value

Type	Description
System.Double

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BufferSize

Declaration

public double BufferSize { get; set; }

Property Value

Type	Description
System.Double

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CaptureType

Gets the capture type (File or Camera)

Declaration

public CaptureType CaptureType { get; }

Property Value

Type	Description
CaptureType

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Contrast

Gets or sets contrast of image (only for cameras)

Declaration

public double Contrast { get; set; }

Property Value

Type	Description
System.Double

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ConvertRgb

Boolean flags indicating whether images should be converted to RGB

Declaration

public bool ConvertRgb { get; set; }

Property Value

Type	Description
System.Boolean

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Exposure

Exposure (only for cameras)

Declaration

public double Exposure { get; set; }

Property Value

Type	Description
System.Double

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Focus

Declaration

public double Focus { get; set; }

Property Value

Type	Description
System.Double

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Format

The format of the Mat objects returned by retrieve()

Declaration

public int Format { get; set; }

Property Value

Type	Description
System.Int32

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FourCC

Gets or sets 4-character code of codec

Declaration

public string FourCC { get; set; }

Property Value

Type	Description
System.String

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Fps

Gets or sets frame rate

Declaration

public double Fps { get; set; }

Property Value

Type	Description
System.Double

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FrameCount

Gets number of frames in video file

Declaration

public int FrameCount { get; }

Property Value

Type	Description
System.Int32

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FrameHeight

Gets or sets height of frames in the video stream

Declaration

public int FrameHeight { get; set; }

Property Value

Type	Description
System.Int32

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FrameWidth

Gets or sets width of frames in the video stream

Declaration

public int FrameWidth { get; set; }

Property Value

Type	Description
System.Int32

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Gain

Gain of the image (only for cameras)

Declaration

public double Gain { get; set; }

Property Value

Type	Description
System.Double

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Gamma

Declaration

public double Gamma { get; set; }

Property Value

Type	Description
System.Double

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GStreamerQueueLength

default is 1 [CV_CAP_GSTREAMER_QUEUE_LENGTH]

Declaration

public double GStreamerQueueLength { get; set; }

Property Value

Type	Description
System.Double

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Guid

Declaration

public double Guid { get; set; }

Property Value

Type	Description
System.Double

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Hue

Gets or sets hue of image (only for cameras)

Declaration

public double Hue { get; set; }

Property Value

Type	Description
System.Double

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Iris

Declaration

public double Iris { get; set; }

Property Value

Type	Description
System.Double

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IsoSpeed

Declaration

public double IsoSpeed { get; set; }

Property Value

Type	Description
System.Double

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Mode

A backend-specific value indicating the current capture mode

Declaration

public int Mode { get; set; }

Property Value

Type	Description
System.Int32

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Monocrome

Declaration

public double Monocrome { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_Baseline

in mm [CV_CAP_PROP_OPENNI_BASELINE]

Declaration

public double OpenNI_Baseline { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_DepthGeneratorBaseline

[CV_CAP_OPENNI_DEPTH_GENERATOR_BASELINE]

Declaration

public double OpenNI_DepthGeneratorBaseline { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_DepthGeneratorFocalLength

[CV_CAP_OPENNI_DEPTH_GENERATOR_FOCAL_LENGTH]

Declaration

public double OpenNI_DepthGeneratorFocalLength { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_DepthGeneratorRegistrationON

[CV_CAP_OPENNI_DEPTH_GENERATOR_REGISTRATION_ON]

Declaration

public double OpenNI_DepthGeneratorRegistrationON { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_FocalLength

in pixels [CV_CAP_PROP_OPENNI_FOCAL_LENGTH]

Declaration

public double OpenNI_FocalLength { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_FrameMaxDepth

in mm [CV_CAP_PROP_OPENNI_FRAME_MAX_DEPTH]

Declaration

public double OpenNI_FrameMaxDepth { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_ImageGeneratorOutputMode

[CV_CAP_OPENNI_IMAGE_GENERATOR_OUTPUT_MODE]

Declaration

public double OpenNI_ImageGeneratorOutputMode { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_OutputMode

[CV_CAP_PROP_OPENNI_OUTPUT_MODE]

Declaration

public double OpenNI_OutputMode { get; set; }

Property Value

Type	Description
System.Double

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OpenNI_Registration

flag that synchronizes the remapping depth map to image map by changing depth generator's view point (if the flag is "on") or sets this view point to its normal one (if the flag is "off"). [CV_CAP_PROP_OPENNI_REGISTRATION]

Declaration

public double OpenNI_Registration { get; set; }

Property Value

Type	Description
System.Double

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Pan

Declaration

public double Pan { get; set; }

Property Value

Type	Description
System.Double

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PosAviRatio

Gets or sets relative position of video file

Declaration

public CapturePosAviRatio PosAviRatio { get; set; }

Property Value

Type	Description
CapturePosAviRatio

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PosFrames

Gets or sets 0-based index of the frame to be decoded/captured next

Declaration

public int PosFrames { get; set; }

Property Value

Type	Description
System.Int32

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PosMsec

Gets or sets film current position in milliseconds or video capture timestamp

Declaration

public int PosMsec { get; set; }

Property Value

Type	Description
System.Int32

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PvAPIMulticastIP

ip for anable multicast master mode. 0 for disable multicast [CV_CAP_PROP_PVAPI_MULTICASTIP]

Declaration

public double PvAPIMulticastIP { get; set; }

Property Value

Type	Description
System.Double

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Rectification

TOWRITE (note: only supported by DC1394 v 2.x backend currently)

Declaration

public double Rectification { get; set; }

Property Value

Type	Description
System.Double

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Roll

Declaration

public double Roll { get; set; }

Property Value

Type	Description
System.Double

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Saturation

Gets or sets saturation of image (only for cameras)

Declaration

public double Saturation { get; set; }

Property Value

Type	Description
System.Double

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Settings

Declaration

public double Settings { get; set; }

Property Value

Type	Description
System.Double

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Sharpness

Declaration

public double Sharpness { get; set; }

Property Value

Type	Description
System.Double

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Temperature

[CV_CAP_PROP_TEMPERATURE]

Declaration

public double Temperature { get; set; }

Property Value

Type	Description
System.Double

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Tilt

Declaration

public double Tilt { get; set; }

Property Value

Type	Description
System.Double

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Trigger

Declaration

public double Trigger { get; set; }

Property Value

Type	Description
System.Double

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TriggerDelay

Declaration

public double TriggerDelay { get; set; }

Property Value

Type	Description
System.Double

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WhiteBalanceBlueU

Declaration

public double WhiteBalanceBlueU { get; set; }

Property Value

Type	Description
System.Double

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WhiteBalanceRedV

Declaration

public double WhiteBalanceRedV { get; set; }

Property Value

Type	Description
System.Double

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XI_AEAG

Automatic exposure/gain [CV_CAP_PROP_XI_AEAG]

Declaration

public double XI_AEAG { get; set; }

Property Value

Type	Description
System.Double

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XI_AEAGLevel

default is 1 [CV_CAP_PROP_XI_AEAG_LEVEL]

Declaration

public double XI_AEAGLevel { get; set; }

Property Value

Type	Description
System.Double

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XI_AEMaxLimit

Maximum limit of exposure in AEAG procedure [CV_CAP_PROP_XI_AE_MAX_LIMIT]

Declaration

public double XI_AEMaxLimit { get; set; }

Property Value

Type	Description
System.Double

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XI_AGMaxLimit

Maximum limit of gain in AEAG procedure [CV_CAP_PROP_XI_AG_MAX_LIMIT]

Declaration

public double XI_AGMaxLimit { get; set; }

Property Value

Type	Description
System.Double

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XI_AutoWB

Automatic white balance [CV_CAP_PROP_XI_AUTO_WB]

Declaration

public double XI_AutoWB { get; set; }

Property Value

Type	Description
System.Double

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XI_DataFormat

Output data format. [CV_CAP_PROP_XI_DATA_FORMAT]

Declaration

public double XI_DataFormat { get; }

Property Value

Type	Description
System.Double

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XI_Downsampling

Change image resolution by binning or skipping.
[CV_CAP_PROP_XI_DOWNSAMPLING]

Declaration

public double XI_Downsampling { get; set; }

Property Value

Type	Description
System.Double

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XI_ExpPriority

Exposure priority (0.5 - exposure 50%, gain 50%). [CV_CAP_PROP_XI_EXP_PRIORITY]

Declaration

public double XI_ExpPriority { get; set; }

Property Value

Type	Description
System.Double

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XI_GpiLevel

Get general purpose level [CV_CAP_PROP_XI_GPI_LEVEL]

Declaration

public double XI_GpiLevel { get; set; }

Property Value

Type	Description
System.Double

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XI_GpiMode

Set general purpose input mode [CV_CAP_PROP_XI_GPI_MODE]

Declaration

public double XI_GpiMode { get; set; }

Property Value

Type	Description
System.Double

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XI_GpiSelector

Selects general purpose input [CV_CAP_PROP_XI_GPI_SELECTOR]

Declaration

public double XI_GpiSelector { get; set; }

Property Value

Type	Description
System.Double

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XI_GpoMode

Set general purpose output mode [CV_CAP_PROP_XI_GPO_MODE]

Declaration

public double XI_GpoMode { get; set; }

Property Value

Type	Description
System.Double

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XI_GpoSelector

Selects general purpose output [CV_CAP_PROP_XI_GPO_SELECTOR]

Declaration

public double XI_GpoSelector { get; set; }

Property Value

Type	Description
System.Double

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XI_LedMode

Define camera signalling LED functionality [CV_CAP_PROP_XI_LED_MODE]

Declaration

public double XI_LedMode { get; set; }

Property Value

Type	Description
System.Double

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XI_LedSelector

Selects camera signalling LED [CV_CAP_PROP_XI_LED_SELECTOR]

Declaration

public double XI_LedSelector { get; set; }

Property Value

Type	Description
System.Double

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XI_ManualWB

Calculates White Balance(must be called during acquisition) [CV_CAP_PROP_XI_MANUAL_WB]

Declaration

public double XI_ManualWB { get; set; }

Property Value

Type	Description
System.Double

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XI_OffsetX

Horizontal offset from the origin to the area of interest (in pixels). [CV_CAP_PROP_XI_OFFSET_X]

Declaration

public double XI_OffsetX { get; set; }

Property Value

Type	Description
System.Double

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XI_OffsetY

Vertical offset from the origin to the area of interest (in pixels). [CV_CAP_PROP_XI_OFFSET_Y]

Declaration

public double XI_OffsetY { get; set; }

Property Value

Type	Description
System.Double

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XI_Timeout

default is 1 [CV_CAP_PROP_XI_TIMEOUT]

Declaration

public double XI_Timeout { get; set; }

Property Value

Type	Description
System.Double

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XI_TrgSoftware

Generates an internal trigger. PRM_TRG_SOURCE must be set to TRG_SOFTWARE. [CV_CAP_PROP_XI_TRG_SOFTWARE]

Declaration

public double XI_TrgSoftware { get; set; }

Property Value

Type	Description
System.Double

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XI_TrgSource

Defines source of trigger. [CV_CAP_PROP_XI_TRG_SOURCE]

Declaration

public double XI_TrgSource { get; set; }

Property Value

Type	Description
System.Double

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Zoom

Declaration

public double Zoom { get; set; }

Property Value

Type	Description
System.Double

Methods

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DisposeUnmanaged()

Releases unmanaged resources

Declaration

protected override void DisposeUnmanaged()

Overrides

DisposableCvObject.DisposeUnmanaged()

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FromCamera(Int32, VideoCaptureAPIs)

Opens a camera for video capturing

Declaration

public static VideoCapture FromCamera(int index, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.Int32	index	id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
VideoCaptureAPIs	apiPreference	preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.

Returns

Type	Description
VideoCapture

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FromFile(String, VideoCaptureAPIs)

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Declaration

public static VideoCapture FromFile(string fileName, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.String	fileName	it can be: name of video file (e.g. `video.avi`) or image sequence (e.g. `img_%02d.jpg`, which will read samples like `img_00.jpg, img_01.jpg, img_02.jpg, ...`) or URL of video stream (e.g. `protocol://host:port/script_name?script_params\|auth`). Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.
VideoCaptureAPIs	apiPreference	apiPreference preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.

Returns

Type	Description
VideoCapture

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Get(VideoCaptureProperties)

Returns the specified VideoCapture property

Declaration

public double Get(VideoCaptureProperties propertyId)

Parameters

Type	Name	Description
VideoCaptureProperties	propertyId	Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others

Returns

Type	Description
System.Double	Value for the specified property. Value 0 is returned when querying a property that is not supported by the backend used by the VideoCapture instance.

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Get(Int32)

Returns the specified VideoCapture property

Declaration

public double Get(int propertyId)

Parameters

Type	Name	Description
System.Int32	propertyId	Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others

Returns

Type	Description
System.Double	Value for the specified property. Value 0 is returned when querying a property that is not supported by the backend used by the VideoCapture instance.

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GetBackendName()

Returns used backend API name. Note that stream should be opened.

Declaration

public string GetBackendName()

Returns

Type	Description
System.String

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GetExceptionMode()

query if exception mode is active

Declaration

public bool GetExceptionMode()

Returns

Type	Description
System.Boolean

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Grab()

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.

Declaration

public bool Grab()

Returns

Type	Description
System.Boolean	`true` (non-zero) in the case of success.

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IsOpened()

Returns true if video capturing has been initialized already.

Declaration

public bool IsOpened()

Returns

Type	Description
System.Boolean

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Open(Int32, VideoCaptureAPIs)

Opens a camera for video capturing

Declaration

public bool Open(int index, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.Int32	index	id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
VideoCaptureAPIs	apiPreference	preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.

Returns

Type	Description
System.Boolean	`true` if the file has been successfully opened

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Open(String, VideoCaptureAPIs)

Opens a video file or a capturing device or an IP video stream for video capturing.

Declaration

public bool Open(string fileName, VideoCaptureAPIs apiPreference = VideoCaptureAPIs.ANY)

Parameters

Type	Name	Description
System.String	fileName	it can be: name of video file (eg. `video.avi`) or image sequence (eg. `img_%02d.jpg`, which will read samples like `img_00.jpg, img_01.jpg, img_02.jpg, ...`) or URL of video stream (eg. `protocol://host:port/script_name?script_params\|auth`). Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.
VideoCaptureAPIs	apiPreference	apiPreference preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.

Returns

Type	Description
System.Boolean	`true` if the file has been successfully opened

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Read(Mat)

Grabs, decodes and returns the next video frame.

The method/function combines VideoCapture::grab() and VideoCapture::retrieve() in one call. This is the most convenient method for reading video files or capturing data from decode and returns the just grabbed frame. If no frames has been grabbed (camera has been disconnected, or there are no more frames in video file), the method returns false and the function returns empty image (with %cv::Mat, test it with Mat::empty()).

Declaration

public bool Read(Mat image)

Parameters

Type	Name	Description
Mat	image

Returns

Type	Description
System.Boolean	`false` if no frames has been grabbed

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Read(OutputArray)

Grabs, decodes and returns the next video frame.

Declaration

public bool Read(OutputArray image)

Parameters

Type	Name	Description
OutputArray	image

Returns

Type	Description
System.Boolean	`false` if no frames has been grabbed

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Release()

Closes video file or capturing device.

Declaration

public void Release()

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Retrieve(Mat, CameraChannels)

Decodes and returns the grabbed video frame.

The method decodes and returns the just grabbed frame. If no frames has been grabbed (camera has been disconnected, or there are no more frames in video file), the method returns false and the function returns an empty image (with %cv::Mat, test it with Mat::empty()).

Declaration

public bool Retrieve(Mat image, CameraChannels streamIdx)

Parameters

Type	Name	Description
Mat	image	the video frame is returned here. If no frames has been grabbed the image will be empty.
CameraChannels	streamIdx	non-zero streamIdx is only valid for multi-head camera live streams

Returns

Type	Description
System.Boolean

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Retrieve(Mat, Int32)

Decodes and returns the grabbed video frame.

Declaration

public bool Retrieve(Mat image, int flag = 0)

Parameters

Type	Name	Description
Mat	image	the video frame is returned here. If no frames has been grabbed the image will be empty.
System.Int32	flag	it could be a frame index or a driver specific flag

Returns

Type	Description
System.Boolean

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Retrieve(OutputArray, CameraChannels)

Decodes and returns the grabbed video frame.

Declaration

public bool Retrieve(OutputArray image, CameraChannels streamIdx)

Parameters

Type	Name	Description
OutputArray	image	the video frame is returned here. If no frames has been grabbed the image will be empty.
CameraChannels	streamIdx	non-zero streamIdx is only valid for multi-head camera live streams

Returns

Type	Description
System.Boolean

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Retrieve(OutputArray, Int32)

Decodes and returns the grabbed video frame.

Declaration

public bool Retrieve(OutputArray image, int flag = 0)

Parameters

Type	Name	Description
OutputArray	image	the video frame is returned here. If no frames has been grabbed the image will be empty.
System.Int32	flag	it could be a frame index or a driver specific flag

Returns

Type	Description
System.Boolean

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RetrieveMat()

Decodes and returns the grabbed video frame.

Declaration

public Mat RetrieveMat()

Returns

Type	Description
Mat	the video frame is returned here. If no frames has been grabbed the image will be empty.

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Set(VideoCaptureProperties, Double)

Sets a property in the VideoCapture.

Declaration

public bool Set(VideoCaptureProperties propertyId, double value)

Parameters

Type	Name	Description
VideoCaptureProperties	propertyId	Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others
System.Double	value	Value of the property.

Returns

Type	Description
System.Boolean	`true` if the property is supported by backend used by the VideoCapture instance.

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Set(Int32, Double)

Sets a property in the VideoCapture.

Declaration

public bool Set(int propertyId, double value)

Parameters

Type	Name	Description
System.Int32	propertyId	Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others
System.Double	value	Value of the property.

Returns

Type	Description
System.Boolean	`true` if the property is supported by backend used by the VideoCapture instance.

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SetExceptionMode(Boolean)

Switches exceptions mode. methods raise exceptions if not successful instead of returning an error code

Declaration

public void SetExceptionMode(bool enable)

Parameters

Type	Name	Description
System.Boolean	enable

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WaitAny(IEnumerable<VideoCapture>, out Int32[], Int64)

Wait for ready frames from VideoCapture.

The primary use of the function is in multi-camera environments. The method fills the ready state vector, grabs video frame, if camera is ready.

After this call use VideoCapture::retrieve() to decode and fetch frame data.

Declaration

public static bool WaitAny(IEnumerable<VideoCapture> streams, out int[] readyIndex, long timeoutNs = 0L)

Parameters

Type	Name	Description
IEnumerable<VideoCapture>	streams	input video streams
System.Int32[]	readyIndex	stream indexes with grabbed frames (ready to use .retrieve() to fetch actual frame)
System.Int64	timeoutNs	number of nanoseconds (0 - infinite)

Returns

Type	Description
System.Boolean	`true if streamReady is not empty

Exceptions

Type	Condition
OpenCVException	Exception %Exception on stream errors (check .isOpened() to filter out malformed streams) or VideoCapture type is not supported

Implements

ICvPtrHolder