Technical Reference:BCI2000 Messages - Revision history

Mellinger: /* Descriptor=6: System Command */

2024-10-22T16:04:31Z

Descriptor=6: System Command

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	===Descriptor=6: System Command===		===Descriptor=6: System Command===
	A system command consists of an ASCII string that ~~may~~ end with a		A system command consists of an ASCII string that must end with a
	zero byte (i.e., ASCII code 0).		zero byte (i.e., ASCII code 0).
	The nature of these system commands is defined by the specific		The nature of these system commands is defined by the specific

Mellinger: /* Descriptor Supplement=3: Signal Properties */

2024-05-02T16:11:05Z

Descriptor Supplement=3: Signal Properties

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	<math>\phi = (r-a)b\Sigma</math>		<math>\phi = (r-a)b\Sigma</math>

	In a Signal Properties message, a physical unit is represented as a white-space separated list of offset, gain, ~~and~~ symbol. Physical units are transmitted per-channel without further separation, and the entire list is enclosed in curly braces.		In a Signal Properties message, a physical unit is represented as a white-space separated list of
			* offset,
			* gain,
			* symbol,
			* raw minimum,
			* raw maximum.
			Physical units for data values are transmitted per-channel without further separation, and the entire list is enclosed in curly braces.

	All values are separated by white space. When containing braces or white space, these are encoded according to the URL convention, i.e. a character is encoded by its corresponding hexadecimal number in Latin-1 encoding, prepended with a percent sign.		All values are separated by white space. When containing braces or white space, these are encoded according to the URL convention, i.e. a character is encoded by its corresponding hexadecimal number in Latin-1 encoding, prepended with a percent sign.

Mellinger: /* Descriptor Supplement=3: Signal Properties */

2024-05-02T16:08:34Z

Descriptor Supplement=3: Signal Properties

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	====Descriptor Supplement=3: Signal Properties====		====Descriptor Supplement=3: Signal Properties====
	For messages transferring Signal Properties, the ''descriptor supplement'' is 3.		For messages transferring Signal Properties, the ''descriptor supplement'' is 3.
	The Signal Properties type represents information about a signal, i.e. a signal name, channel and element (sample) indices, a signal type, and ~~the~~ physical units in the signal's dimensions (channels, elements, and values).		The Signal Properties type represents information about a signal, i.e.
			* a signal name,
			* channel and element (sample) indices,
			* a signal type, and
			* physical units in the signal's dimensions (channels, elements, and values).

	For channels as well as elements, an index is defined, consisting of a label for each entry in the list of channels resp. elements. Labels may be either trivial, i.e. consist of the numbers from 1 to the number of entries, or nontrivial, consisting of arbitrary character strings. In the first, trivial, case, the index' representation in the message will be the number of its entries. In the second, nontrivial, case, it will be represented by a white-space separated list of its entries (labels), enclosed in curly braces.		For channels as well as elements, an index is defined, consisting of a label for each entry in the list of channels resp. elements. Labels may be either trivial, i.e. consist of the numbers from 1 to the number of entries, or nontrivial, consisting of arbitrary character strings. In the first, trivial, case, the index' representation in the message will be the number of its entries. In the second, nontrivial, case, it will be represented by a white-space separated list of its entries (labels), enclosed in curly braces.

Mellinger: /* Descriptor Supplement=3: Signal Properties */

2024-05-02T16:07:02Z

Descriptor Supplement=3: Signal Properties

← Older revision		Revision as of 16:07, 2 May 2024
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	For channels as well as elements, an index is defined, consisting of a label for each entry in the list of channels resp. elements. Labels may be either trivial, i.e. consist of the numbers from 1 to the number of entries, or nontrivial, consisting of arbitrary character strings. In the first, trivial, case, the index' representation in the message will be the number of its entries. In the second, nontrivial, case, it will be represented by a white-space separated list of its entries (labels), enclosed in curly braces.		For channels as well as elements, an index is defined, consisting of a label for each entry in the list of channels resp. elements. Labels may be either trivial, i.e. consist of the numbers from 1 to the number of entries, or nontrivial, consisting of arbitrary character strings. In the first, trivial, case, the index' representation in the message will be the number of its entries. In the second, nontrivial, case, it will be represented by a white-space separated list of its entries (labels), enclosed in curly braces.

	In a message, the signal type is represented by its ID, which is one of int16, int32, float24, or float32.		In a message, the signal type is represented by its ID, which is one of "int16", "int32", "float24", or "float32".

	Physical units are encoded as an offset <math>a</math>, gain <math>b</math>, and a symbol <math>\Sigma</math>, such that a physical value <math>\phi</math> is computed from the raw value <math>r</math> as follows:		Physical units are encoded as an offset <math>a</math>, gain <math>b</math>, and a symbol <math>\Sigma</math>, such that a physical value <math>\phi</math> is computed from the raw value <math>r</math> as follows:

Mellinger: /* Descriptor Supplement=3: Signal Properties */

2024-05-02T16:06:34Z

Descriptor Supplement=3: Signal Properties

← Older revision		Revision as of 16:06, 2 May 2024
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	<math>\phi = (r-a)b\Sigma</math>		<math>\phi = (r-a)b\Sigma</math>

	In a Signal Properties message, a physical unit is represented as a white-space separated list of offset, gain, and symbol, enclosed in curly braces.		In a Signal Properties message, a physical unit is represented as a white-space separated list of offset, gain, and symbol. Physical units are transmitted per-channel without further separation, and the entire list is enclosed in curly braces.

	All values are separated by white space. When containing braces or white space, these are encoded according to the URL convention, i.e. a character is encoded by its corresponding hexadecimal number in Latin-1 encoding, prepended with a percent sign.		All values are separated by white space. When containing braces or white space, these are encoded according to the URL convention, i.e. a character is encoded by its corresponding hexadecimal number in Latin-1 encoding, prepended with a percent sign.

Mellinger: /* Descriptor Supplement=5: VideoFrame Data */

2024-04-22T15:31:27Z

Descriptor Supplement=5: VideoFrame Data

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	Similar to the Bitmap data type, a VideoFrame represents a bitmap picture. Bitmap data are specialized for screen content, which may be color reduced and RLE-compressed efficiently, whereas VideoFrame data are intended for video content, and are transferred as raw RGB24 data. To increase efficiency of transmission, VideoFrame data may be stored in shared memory, and only transmitted by a reference to that shared memory in case of a local connection.		Similar to the Bitmap data type, a VideoFrame represents a bitmap picture. Bitmap data are specialized for screen content, which may be color reduced and RLE-compressed efficiently, whereas VideoFrame data are intended for video content, and are transferred as raw RGB24 data. To increase efficiency of transmission, VideoFrame data may be stored in shared memory, and only transmitted by a reference to that shared memory in case of a local connection.

	In a VideoFrame message, a leading flag byte is transmitted first, followed by width and height of the picture as two-byte integers in little-endian format. Then, <tt>width * height * 4</tt> bytes of content follow.		In a VideoFrame message, a leading flag byte is transmitted first, followed by width and height of the picture as two-byte integers in little-endian format. Then, <tt>widthheight4</tt> bytes of content follow.
	The flag byte holds two pieces of information:		The flag byte holds two pieces of information:
	* endianness of the data, and		* endianness of the data, and

Mellinger: /* Descriptor Supplement=4: Bitmap Data */

2024-04-22T15:30:43Z

Descriptor Supplement=4: Bitmap Data

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	In a bitmap message, first width and height of the picture are transmitted as two-byte integers in little-endian format. Then, run-length data follow in this format: For each run, run-length reduced by 1 is transmitted as an unsigned byte first. Then, its associated color value follows, as a two-byte integer in little-endian format. Thus, maximum run length is 256. Runs are wrapped at the picture's right edge, and runs follow each other until the picture's specified height and width are filled with color data.		In a bitmap message, first width and height of the picture are transmitted as two-byte integers in little-endian format. Then, run-length data follow in this format: For each run, run-length reduced by 1 is transmitted as an unsigned byte first. Then, its associated color value follows, as a two-byte integer in little-endian format. Thus, maximum run length is 256. Runs are wrapped at the picture's right edge, and runs follow each other until the picture's specified height and width are filled with color data.

			====Descriptor Supplement=5: VideoFrame Data====
			Similar to the Bitmap data type, a VideoFrame represents a bitmap picture. Bitmap data are specialized for screen content, which may be color reduced and RLE-compressed efficiently, whereas VideoFrame data are intended for video content, and are transferred as raw RGB24 data. To increase efficiency of transmission, VideoFrame data may be stored in shared memory, and only transmitted by a reference to that shared memory in case of a local connection.

			In a VideoFrame message, a leading flag byte is transmitted first, followed by width and height of the picture as two-byte integers in little-endian format. Then, <tt>width * height * 4</tt> bytes of content follow.
			The flag byte holds two pieces of information:
			* endianness of the data, and
			* a flag that indicates whether transmission content is the full image, or a reference to shared memory. In the second case, the video data is replaced with a zero-delimited string holding the name of an existing shared memory object.

	====Descriptor Supplement=255: Visualization Configuration====		====Descriptor Supplement=255: Visualization Configuration====

Mellinger: /* Descriptor=3: State Format */

2024-04-04T14:24:37Z

Descriptor=3: State Format

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	[[Technical Reference:State Definition\|state definition]] line.		[[Technical Reference:State Definition\|state definition]] line.
	Note that, for transportation of state values between core modules during processing, state vector messages (Descriptor=5) are used rather than state messages. Typically, state messages are used to transfer information about states, or values of individual states, and state vector messages are used to transfer the values of all existing states at a given point in time.		Note that, for transportation of state values between core modules during processing, state vector messages (Descriptor=5) are used rather than state messages. Typically, state messages are used to transfer information about states, or values of individual states, and state vector messages are used to transfer the values of all existing states at a given point in time.

			====Descriptor Supplement=0: Original State Format====
			State information is transferred in the [[Technical Reference:State Definition#State_Lines\|original state format]].

			====Descriptor Supplement=1: Alternate State Format====
			State information is transferred in the [[Technical Reference:State Definition#Alternate_version_of_State_Lines\|alternate state format]].

	===Descriptor=4: Visualization and Brain Signal Data Format===		===Descriptor=4: Visualization and Brain Signal Data Format===

Mellinger: /* Descriptor Supplement=1: Signal Data */

2024-02-01T17:08:46Z

Descriptor Supplement=1: Signal Data

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	The number of channels and samples are sent as "length fields" in the sense explained above, using binary encoding for small numbers, and ASCII representation to allow for arbitrarily large numbers.		The number of channels and samples are sent as "length fields" in the sense explained above, using binary encoding for small numbers, and ASCII representation to allow for arbitrarily large numbers.

			Note that the ''Source identifier'' field may be set to <tt>0xff</tt> and is then followed with a null-terminated string representing a string-valued source identifier.

	[[Image:BCI2000_Messages_vistype1(graph).png\|center\|thumb\|600px\|One message if the visualization type is 1 (signal data).]]		[[Image:BCI2000_Messages_vistype1(graph).png\|center\|thumb\|600px\|One message if the visualization type is 1 (signal data).]]

Mellinger: /* Descriptor Supplement=1: Signal Data */

2024-02-01T16:57:46Z

Descriptor Supplement=1: Signal Data

← Older revision		Revision as of 16:57, 1 February 2024
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	The number of channels and samples are sent as "length fields" in the sense explained above, using binary encoding for small numbers, and ASCII representation to allow for arbitrarily large numbers.		The number of channels and samples are sent as "length fields" in the sense explained above, using binary encoding for small numbers, and ASCII representation to allow for arbitrarily large numbers.

	[[Image:BCI2000_Messages_vistype1(graph).~~svg~~\|center\|thumb\|600px\|One message if the visualization type is 1 (signal data).]]		[[Image:BCI2000_Messages_vistype1(graph).png\|center\|thumb\|600px\|One message if the visualization type is 1 (signal data).]]

	[[Image:BCI2000_Messages_TransmittedVisualizationDataFormat.png\|center\|thumb\|500px\|Graphical representation of the transmitted visualization data format.]]		[[Image:BCI2000_Messages_TransmittedVisualizationDataFormat.png\|center\|thumb\|500px\|Graphical representation of the transmitted visualization data format.]]