VideoCapture

Video capture

VideoCapture object provides means to grab images from a source. It implements all required functionality including video device initialization, setup, start/stop of capture and frame grabbing. Internally VideoCapture utilizes ImageBuffer as storage.

Extends

VideoSource

Constructors

Constructor

new VideoCapture(): VideoCapture

Constructor

Returns

VideoCapture

Overrides

VideoSource.constructor

Properties

aspectRatio?

protected optional aspectRatio: number

Aspect ratio

Inherited from

VideoSource.aspectRatio

buffer

buffer: ImageBuffer

Context of original stream

Inherited from

VideoSource.buffer

captureTime

captureTime: number = 0

Timestamp of the last captured frame

Inherited from

VideoSource.captureTime

clipRect?

protected optional clipRect: ClipRect

Clipping rectangle

Inherited from

VideoSource.clipRect

sizeMax?

protected optional sizeMax: number

Maximum capture resolutions

Inherited from

VideoSource.sizeMax

transpose?

protected optional transpose: boolean

Transpose frames

Inherited from

VideoSource.transpose

videoRef

protected videoRef: HTMLVideoElement

Video element

Methods

addListener()

addListener<E>(event, listener): this

Adds the listener function to the end of the listeners array

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.addListener

capture()

capture(): boolean

Grab the next video frame

VideoCapture grabs the next image from a video source (camera) and stores it in embedded ImageBuffer.

Returns

boolean

True if next frame was available and grabbed

Overrides

VideoSource.capture

dispose()

dispose(): void

Dispose video capture object

Returns

void

Overrides

VideoSource.dispose

emit()

emit<E>(event, …args): boolean

Synchronously calls each of the listeners registered for the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

args

…Args<CaptureEvents[E]>

Arguments passed to the listeners

Returns

boolean

True if the event had listeners, False otherwise

Inherited from

VideoSource.emit

eventNames()

eventNames(): (string | symbol)[]

List of emitter’s events

Returns

(string | symbol)[]

List of emitter’s events

Inherited from

VideoSource.eventNames

getMaxListeners()

getMaxListeners(): number

Maximum number of listeners per event

Returns

number

Maximum number of listeners per event

Inherited from

VideoSource.getMaxListeners

listenerCount()

listenerCount<E>(event): number

The number of listeners listening to the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

Returns

number

Number of listeners

Inherited from

VideoSource.listenerCount

listeners()

listeners<E>(event): Function[]

Copy of the array of listeners for the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

Returns

Function[]

Copy of the listeners array

Inherited from

VideoSource.listeners

off()

off<E>(event, listener): this

Removes the listener from the listener array for the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.off

on()

on<E>(event, listener): this

Adds the listener function to the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.on

once()

once<E>(event, listener): this

Adds a one-time listener function for the event

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.once

pause()

pause(): void

Pause video capture

Returns

void

Overrides

VideoSource.pause

prependListener()

prependListener<E>(event, listener): this

Adds the listener function to the beginning of the listeners array

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.prependListener

prependOnceListener()

prependOnceListener<E>(event, listener): this

Adds a one-time listener function to the beginning of the listeners array

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

Inherited from

VideoSource.prependOnceListener

ratio()

ratio(): number

Aspect ratio of the video stream

Returns

number

Aspect ratio of the video stream

Inherited from

VideoSource.ratio

rawListeners()

rawListeners<E>(event): Function[]

Copy of the array of listeners for the event including wrappers

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

Returns

Function[]

Copy of the listeners array

Inherited from

VideoSource.rawListeners

removeAllListeners()

removeAllListeners<E>(event?): this

Removes all listeners, or those of the specified event

Type Parameters

E

E extends "resize"

Parameters

event?

E

The name of the event

Returns

this

This EventEmitter

Inherited from

VideoSource.removeAllListeners

removeListener()

removeListener<E>(event, listener): this

Removes the specified listener from the listener array

Type Parameters

E

E extends "resize"

Parameters

event

E

The name of the event

listener

CaptureEvents[E]

The callback function

Returns

this

This EventEmitter

Inherited from

VideoSource.removeListener

reset()

reset(): void

Reset video capture

After reset() capture may be started again only after setup().

Returns

void

Overrides

VideoSource.reset

setMaxListeners()

setMaxListeners(n): this

Sets maximum number of listeners per event

Parameters

n

number

Maximum number of listeners

Returns

this

This EventEmitter

Inherited from

VideoSource.setMaxListeners

setup()

setup(params?): Promise<boolean>

Setup video capture

Sets up video device, streams and contexts with canvases. Video capture can be setup by simplified VideoParams opening default front/rear camera with provided resolution. Additional fine-grained MediaStreamConstraints can be passed via opts field providing the most flexible way to setup video stream (for example, by requesting specific deviceId). Stream constraints have higher priority than rest or params. Another options are an external MediaStream allowing custom video sources (e.g. remote stream) or a media file defined by url or FileParams that allows to limit maximum capture size in cases resolution is too big for a device.