Video Player Element

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Modified on 2018/07/16 00:51 by Administrator Categorized as Base Elements, Elements, Visual Stimuli

» Video Player Element

Summary ¶

	Video player
Info
Category:	Visual Stimuli	AddIn:	Base Layer
Creator:	OkazoLab	Scope:	Parent event
Owns Snippets:	None	Usage:	Stimulus screen

Properties ¶

Name	Description	Constraints	Type
Playback
Playback Mode	Defines the playback mode for a video clip: 1) manual playback. 2) Single playback on the event onset (default mode). 3) Looped playback after event onset.	Normal..	stPlay..
Volume	Defines the volume of the audio playback, in percentages, from 0 (ground) to 100 (full)	Normal..	Int32
Balance	Defines the stereophonic balance of the audio playback, from 100 (most left) to 100 (most right)	Normal..	Int32
Start position	Defines the start position of video playback in percentages (0..100) to the total duration of the current video clip.	Normal..	Double
Current Position	Indicates the current playback position defined in percentages to the total duration of the current video clip. While a clip is playing, the position can be retrieved or adjusted to rewind the clip	Normal..	Double
Current Frame	Represents the current playback position defined by a number of video frame. While a clip is playing, the frame number can be read or adjusted to rewind the clip	Normal..	Double
Current Time	Represents the current playback position defined by a time (in ms). While a clip is playing, the property can be read or adjusted to rewind the clip	Normal..	clTime
Is Playing	Play Method	Normal..	Boolean
Clip Info
Frame Rate	Original frame rate of the current clip in frames/second	Status..	Double
Duration	Duration of the current clip in seconds	Status..	Double
Number of Frames	Return a number of video frames in the current clip	Status..	Int32
Frame Size	Original frame size of the current clip	Status..	clSize
Runtime Status
Start Time	The property stores the actual event time when the last playback started	Status..	clTime
End Time	The property stores the actual event time when the last playback ended	Status..	clTime
Is Triggered	If Monitor Playback property is true, this property indicates if the element has been triggered at least once after activation of the parent event. Triggering occurs each time when the playback ends.	Normal..	Boolean
Actual Framerate	Actual frame rate of video playback at runtime	Normal..	Double
Material List
Selected Index	Defines an index of the selected library item in the list of this element	Normal..	Int32
Selected Item	Defines a name if the selected library item in the list of this element	Normal..	String
Item Count	Return the total number of material items in the list of this element	Status..	Int32
Visual Appearance
Alpha Masking	Defines, whether the visual content is used to create an opacity mask on the event surface. If masking is on, the content's pixel luminance (or, its inverse) defines transparency within element's viewport. The alpha masking allows, for example, create transparent holes on the event surface.	Design Time..	Int32
AntiAliasing	if true, the rendered content will be antialiased for smoother visual appeariance. If false, rendering will be authentic to its source, e.g. a bitmap.	Normal..	Boolean
Position	Defines a position of the rendering viewport on the screen	Normal..	clPoint
Size	Defines a size of the element's rendering viewport on the screen	Normal..	clSize
Z Order	Indicates Z Order of the element on the given event	Status..	Int32
Pivot Point	Defines alignment of the pivot point (or, element's position) relative to element's rendering area. The pivot point sets the center of element's rotation and scale directions.	Normal..	stAlig..
Visible	Defines whether the element is visible	Normal..	Boolean
Rotation	Rotation angle in degrees	Normal..	Double
Effects
Transparent Color	The color of the original pixels of rendered content that will be set as transparent	Normal..	stColor
Transparent Tolerance	Tolerance ratio for choosing colors that become transparent. Zero means that effect is not applied, 1 denotes that all colors will become trasparent	Normal..	Int32
Color Mask	Produces a multiplicative combination of the original pixels and the selected mask color (except the alpha channel). The effect emulates a look through a colored glass. White or transparent mask color dont change the original pixels	Normal..	stColor
Opacity	Opacity of the rendered content	Normal..	Int32
Contrast	Contrast of the rendered content	Normal..	Int32
Brightness	Brightness the rendered content	Normal..	Int32
Saturation	Saturation of the rendered content	Normal..	Double
Pixelation	Pixelation of the rendered content	Normal..	Int32
Blurring	The radius used in the gaussian blur of rendered content, as a pixel-based factor. The default is 0 which means no blurring.	Normal..	Int32
Scrambling		Normal..	Double
Scrambling Grid Size	Defines a size of the scrambling grid	Normal..	clSize
Positional Jitter
Reset Jitter Now	Runtime command that resets the positional jitter.	Runtime Command..	Boolean
Current Jitter	Returns the current jitter	Status..	clPoint
Jitter Range	Defines a possible range for the random jitter. The range is centered to the position of the element.	Normal..	clSize
Test Jitter	Click to test the current jitter	Design Time..	Boolean
Control
Is Enabled	If set to false the element is completely omitted when the experiment is run	Design Time..	Boolean
Title	Title of the element	Design Time..	String

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Video Player Element is capable of showing videos in experiments.

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Summary
Properties

Description
Snapshots
Practical Use
Adding a video to an event
Notes

Description ¶

Video Player element allows playback of video clips stored in Material Library. Different video formats are supported depending on installed codecs. The element provides all playback controls, time audit and various rendering options. Multiple clips can be loaded into element's list in order to form a stimulus set.

Snapshots ¶

Snapshot 1

Snapshot 2

Practical Use ¶

The selected clip will be shown inside of a rectangular area on the screen and its appearance can be modified with properties values that you define for the Video element. For example, you can apply the visual effects for all video frames or adjust the size and rotation angle of the video window.

Video element also can work with a list of video clips loaded from the experiment Library. It's handy for experimental scenarios where you need to present a random video clip at the same position on the screen. For example, you can define which video resources in the Library have to be in the element's resource list and choose an appropriate list index in the Video element at the start of each trial. All video clips will be rendered at the same position with the same size and visual properties that you have defined for the given Video element.

Video element gives you a full control on the playback process: you can stop the playback, re-run it and rewind a video clip to the certain playback position.

Adding a video to an event ¶

Find the video clip that you wish to play and add it to the Material Library.
On an event, click on "add element". From the 'MULTIMEDIA' category, select the Video player element
Drag the media item from the material library onto the video player element in the left element plane. (Not onto the square on the event surface)
Now you may adjust the size of the player by dragging the corners and you can adjust the relevant properties. (e.g Play back mode etc...)

Notes ¶

By default, the playback start in Video element is synchronized with the activation of the parent event. You can use multiple Video elements in the same event but, in this case, they will be started one by one, usually with a neglible delay.

Rendering of video clip frames is synchronized both with clip's timeline and the settings in your experiment. If you have enabled the synchronization with vertical monitor retraces in your experiment, each video frame will be also synchronized with it. The accurate timing of a video playback is not guaranteed and depends on a current computer load. However, you can always measure the actual duration of each frame in a playing video clip. Each time the new video frame is about to be rendered EventIDE calls OnPreparing snippet of the parent event. Checking the current time (e.g., by reading the Elapsed Time property of the parent event) inside of this snippet and comparing it with the previous call of the same snippet will give you a quite accurate measure of a single frame duration. If multiple video clips are shown simultaneously, then the same OnPreparing call can be made before rendering several frames in parallel.

	Name	Size
	Video-player-Element-Icon.png	4.21 KB

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