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Element Icon Video Player Element
Category: Multimedia AddIn: Base Elements
Creator: OkazoLab Team Scope: Parent Event
Owns Snippets: no Usage: Runtime Screen,Snippets

Synchronized Internal Actions

Experiment StartParent Event OnsetStatus change between Onset/OffsetParent Event OffsetExperiment End
If playback mode is set to 'single' or 'looped' playback,
then start playback upon onset.
1) Elements are triggered when the clip is finished playing.
2) For every frame, the parent's redrawing snipped is called.
All playback is aborted.

Generic Properties

NameDescriptionConstraintsValue TypeUpon Change
Playback ModeDefines how the clip is played. 0 - manual playback. 1 - Single playback on the event onset (default, i.e clip is automatically played). 2 Looped playback on event onset.,stPlayMethod, Int32
Is PlayingAt the runtime indicates if the current video clip is playing at the given moment of time. While the clip is playing, you can set this property to false to make a pause in a playback. If the playback has finished, setting this property to true will initiate the playback again.BooleanUpon changing to false, the video will stop playing. Similarly for true.
VolumeVolume of the audio playback, from the ground (0) to full (100),Int32
BalanceStereophonic balance of the audio playback, from -100 (left) to 100 (right). Zero is default center.,Int32
PositionThe current position of the playback, in percents. The property can be used for the adjustment of the playback position at the runtime. If the property value is set to non-zero at the design time, then the playback in an experiment will start from the set position.,floatPlayback position is shifted, (e.g Rewinding)
Current FrameDescribes the current playback position defined by a number of video frame. While a clip is playing, the frame number can be retrieved or adjusted to rewind the clip Int32
Current PositionDescribes 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 Double

+=== Properties inherited from clVisualElement ===
NameDescriptionConstraintsValue TypeUpon Runtime Change
Alpha MaskingDefines whether the visual content rendered by this element will be used as an opacity mask which is applied onto the given event surface. The active opacity mask allows one to expose pixels of the parent event surface through a solid background of the given event. If the value is true, the darker pixels of the content will make more transparent holes on the entire event surface.Boolean
AntiAliasingIf true, the rendered content will be anti-aliased for smoother visual appearance. If false, rendering will be authentic to its source, e.g. a bitmap. Boolean
PositionDefines the position of the element viewport on the screen. The position can be set in any of three coordinate systems: a) pixels, b) polar, c) central. clPoint
SizeDefines the size of the element viewport on the screen. The size can be set in any of three coordinate systems: a) pixels, b) visual degrees, c) 'relative-to-screen' size. clSize
Z OrderIndicates the current depth order of the element viewport on the surface of the parent event. The greatest number corresponds to the top position. The order can be changed by moving the element up and down in the element list.Int32
Pivot PointDefines the pivot point (coordinate and the rotation centers) within the element viewport. stAlignment or Int32
VisibleDefines whether the element is currently visible on the event surface. The property is convenient for switching visual content on and off. Boolean
RotationDefines the rotation angle (in degrees) of element viewport relative to the its pivot point. Double in the range 0..360
Transparent ColorThe color of the original pixels of rendered content that will be set as transparent. stColor
Transparency ToleranceTolerance ratio for choosing colors that become transparent. Zero means that effect is not applied, 1 denotes that all colors will become trasparent. Int32, range (0..100)
Color MaskProduces 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 doesn't change the original pixels. stColor
OpacityOpacity of the rendered content. Int32, range (0..100)
ContrastContrast of the rendered content. Int32, range (-100..100)
BrightnessDefines the brighness of the rendered content. Int32, range (-100..100)
SaturationSaturation of the rendered content. Double
PixelationDefines the pixel scale of the rendering. Int32, range (0..100)
BlurringThe radius used in the gaussian blur of rendered content, as a pixel-based factor. The default is 0 which means no blurring. Int32
Reset JitterSet to true at runtime to reset the current positional jitter.Boolean, set true for action
Current JitterJitter range, in pixels (non inclusive)..clSize
Jitter RangeJitter range, centered at the original position of the element.. clSize

+=== Properties inherited from clElement === Inherited properties of clElement
NameDescriptionConstraintsValue TypeUpon Change
Is EnabledIf set to false the element is completely omitted when the experiment is run.Boolean
TitleTitle of the element.String

Video element is capable to show videos in experiments.


Video Player element allows the playback of video clips that are stored in the 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.



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

  1. Find the video clip that you wish to play and add it to the Material Library.
  2. On an event, click on "add element". From the 'MULTIMEDIA' category, select the Video player element
  3. 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)
  4. 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...)


  • 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.

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