User Reference:BCI2000Viewer - Revision history

Mellinger: /* Audio and Video */

2025-06-04T13:47:50Z

Audio and Video

← Older revision		Revision as of 13:47, 4 June 2025
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	====Audio and Video====		====Audio and Video====
	If both audio and video are to be synchronized with ~~one another~~, and brain signal playback, it is most suitable to use audio playback as a reference time base because ~~Audio~~ is most ~~sensitive~~ to seeking artifacts.		If both audio and video are to be synchronized with each other, and brain signal playback, then it is most suitable to use audio playback as a reference time base because audio is most susceptible to seeking artifacts.

	Similar to the "Audio only" case above, audio is played back directly. For each block of audio data, the current frame is used to seek the <tt>.dat</tt> file to where the		Similar to the "Audio only" case above, audio is played back directly. For each block of audio data, the current frame is used to seek the <tt>.dat</tt> file to where the

Mellinger: /* See also */

2025-06-04T13:46:02Z

Mellinger: /* Audio and Video */

2025-06-04T13:44:17Z

Audio and Video

← Older revision		Revision as of 13:44, 4 June 2025
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	====Audio and Video====		====Audio and Video====
			If both audio and video are to be synchronized with one another, and brain signal playback, it is most suitable to use audio playback as a reference time base because Audio is most sensitive to seeking artifacts.

			Similar to the "Audio only" case above, audio is played back directly. For each block of audio data, the current frame is used to seek the <tt>.dat</tt> file to where the
			<tt>AudioFrame</tt> state matches or exceeds that current audio frame.

			Now that the location for the current audio frame has been found in the <tt>.dat</tt> file, it can be used to obtain the current value <tt>WebcamFrame0</tt>.
			After seeking video to that frame, all three modalities are then synchronized.

	==See also==		==See also==

Mellinger: /* Video Only */

2025-06-04T13:33:00Z

Video Only

← Older revision		Revision as of 13:33, 4 June 2025
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	====Video Only====		====Video Only====
			Video files as written by WebcamLogger are not suitable for direct video playback, as their frame rate [[Contributions:WebcamLogger#Format_of_the_Video_File\|does not match]] the true, possibly variable, frame rate of the recording.

			Thus, a timer is used to smoothly advance brain signal data. Whenever brain signal data has advanced by one step, the value of <tt>WebcamFrame0</tt> is read out, and video is seeked to display exactly that frame.

			As a result, brain signal data, and video, move in a synchronized manner.

	====Audio and Video====		====Audio and Video====

Mellinger: /* Audio Only */

2025-06-04T13:24:49Z

Audio Only

← Older revision		Revision as of 13:24, 4 June 2025
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	====Audio Only====		====Audio Only====
			If only audio data is to be synchronized with brain signal data, the strategy is simply to play back audio at native speed, and to move brain signal data such that the
			<tt>AudioFrame</tt> state matches the current audio playback frame as good as possible. Typically, for each playback audio block, the <tt>.dat</tt> file is seeked until
			<tt>AudioFrame</tt> first exceeds or matches the block's last audio frame, counted from the beginning of audio playback.

	====Video Only====		====Video Only====
	====Audio and Video====		====Audio and Video====

Mellinger: /* AV Synchronization Strategies */

2025-06-04T13:19:31Z

AV Synchronization Strategies

← Older revision		Revision as of 13:19, 4 June 2025
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	Similarly, whenever the [[Contributions:WebcamLogger\|WebcamLogger]] has acquired a frame of video, the current frame count is written into the <tt>WebcamFrame0</tt> event state		Similarly, whenever the [[Contributions:WebcamLogger\|WebcamLogger]] has acquired a frame of video, the current frame count is written into the <tt>WebcamFrame0</tt> event state
	(or with different index as appropriate).		(with different index where appropriate).

	Together with the <tt>SourceTime</tt> timestamp recorded in the BCI2000 .dat file, these event states form the basis for AV synchronization.		Together with the <tt>SourceTime</tt> timestamp recorded in the BCI2000 .dat file, these event states form the basis for AV synchronization.

Mellinger: /* AV Synchronization Strategies */

2025-06-04T13:19:05Z

AV Synchronization Strategies

← Older revision		Revision as of 13:19, 4 June 2025
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	===AV Synchronization Strategies===		===AV Synchronization Strategies===
			While recording audio, the [[Contributions:AudioExtension\|AudioExtension]] will write the current audio frame into the <tt>AudioFrame</tt> event state
			whenever a block of audio data has been processed.

			Similarly, whenever the [[Contributions:WebcamLogger\|WebcamLogger]] has acquired a frame of video, the current frame count is written into the <tt>WebcamFrame0</tt> event state
			(or with different index as appropriate).

			Together with the <tt>SourceTime</tt> timestamp recorded in the BCI2000 .dat file, these event states form the basis for AV synchronization.

	====Audio Only====		====Audio Only====
	====Video Only====		====Video Only====
	====Audio and Video====		====Audio and Video====


	==See also==		==See also==

Mellinger at 12:44, 4 June 2025

2025-06-04T12:44:58Z

← Older revision		Revision as of 12:44, 4 June 2025
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	''BCI2000Viewer'' displays brain signal data and [[BCI2000 Glossary#State\|state variables]] contained in [[Technical Reference:BCI2000 File Format\|BCI2000 data files]].		''BCI2000Viewer'' displays brain signal data and [[BCI2000 Glossary#State\|state variables]] contained in [[Technical Reference:BCI2000 File Format\|BCI2000 data files]].

			For recordings containing audio and/or video content, it can play back audio and/or video in conjunction with scrolling through the data file in real-time.

	[[Image:BCI2000Viewer.PNG]]		[[Image:BCI2000Viewer.PNG]]
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	\|}		\|}

	====Unit Display====		==Unit Display==
	{{UnitDisplay}}		{{UnitDisplay}}

	====Choosing Signal Colors====		==Choosing Signal Colors==
	{{ChooseColors}}		{{ChooseColors}}

			==AV Playback==
			In BCI2000Viewer, there is an AV Playback tool bar floating on top of other windows.
			It allows to scroll through a recording in real-time or a fraction or multiple thereof.
			Also, it contains controls for navigating through a recording, and setting the relative speed of playback.

			If AV content is available, video data will be displayed in secondary windows. Audio will be played back through the output set as default in the system preferences.

			===AV Synchronization Strategies===
			====Audio Only====
			====Video Only====
			====Audio and Video====


	==See also==		==See also==

Mellinger: /* Selecting States and Channels for Display */

2025-06-04T12:10:01Z

Selecting States and Channels for Display

← Older revision		Revision as of 12:10, 4 June 2025
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	To display one or more state, mark the respective checkbox.		To display one or more state, mark the respective checkbox.

	State names and values are displayed above the signal~~; whenever~~ a state ~~changes its~~ value, a ~~vertical line indicates the respective point in time~~, and the state~~'s new~~ value ~~appears at~~ the ~~top end~~ of ~~that line~~.		State names and values are displayed above the signal. State values are normalized to the available range. To see the actual value of a state, move the mouse cursor to the desired position, and let it rest there for one or two seconds. A tooltip will appear, displaying the state name and value.

			==Display Tool Tips==
			Whenever the mouse pointer is at rest for one or two seconds above the channel and state display, a tool tip will be displayed that contains state or channel name, and the state or channel value. This is especially useful for states where there is not enough space in the display to indicate a range of values.

	==Display Properties==		==Display Properties==

Mellinger: /* Browsing */

2025-06-04T12:01:21Z

Browsing

← Older revision		Revision as of 12:01, 4 June 2025
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	==Browsing==		==Browsing==
	User interface elements for browsing are located ~~below~~ the ~~signal display~~.		User interface elements for browsing are located at the top right, within the tool bar.
	*<tt>\|<<</tt> and <tt>>>\|</tt> move to beginning/end of file;		*<tt>\|<<</tt> and <tt>>>\|</tt> move to beginning/end of file;
	*<tt><<</tt> and <tt>>></tt> move forward/backward by entire pages (i.e., the amount of time displayed in the window);		*<tt><<</tt> and <tt>>></tt> move forward/backward by entire pages (i.e., the amount of time displayed in the window);
	*<tt><</tt> and <tt>></tt> move forward/backward by sample blocks;		*<tt><</tt> and <tt>></tt> move forward/backward by sample blocks;
	*''Zoom in'' and ''Zoom out'' enlarge/shrink the time axis;
	*the ''position'' field displays the current position in <tt>hh:mm:ss</tt> format, followed by the total length of the file. Entering a value in seconds, or in <tt>hh:mm:ss</tt> format, will move the center of the display to the specified position.		*the ''position'' field displays the current position in <tt>hh:mm:ss</tt> format, followed by the total length of the file. Entering a value in seconds, or in <tt>hh:mm:ss</tt> format, will move the center of the display to the specified position.

			==Tool Bar==
			The tool bar contains icons for horizontal and vertical zoom, reducing or enlarging the number of channels displayed on a vertical display page. Also, the tool bar allows to enable and disable the display grid, open and close the channel color selector, and switch between light and dark display mode. Further, there are menus for High Pass, Low Pass, and Notch filter options in the tool bar.

			For all tool bar options, there are corresponding menu items in the "View" and the context menu (right-click on the display).

	==Selecting States and Channels for Display==		==Selecting States and Channels for Display==

← Older revision		Revision as of 13:46, 4 June 2025
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	==See also==		==See also==
	[[User Reference:BCI2000FileInfo]]		[[User Reference:BCI2000FileInfo]], [[Contributions:WebcamLogger]], [[Contributions:AudioExtension]]

	[[Category:User Interface]][[Category: Data Analysis Tools]]		[[Category:User Interface]][[Category: Data Analysis Tools]]