Variable Length Value - Revision history

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:43:45Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:43, 15 January 2013
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	</ul>		</ul>

	The <tt>time</tt> value is a measurement of the time to wait between sending the <tt>message</tt> before that time and the <tt>message</tt> after that time. This method of specifying the time is called '''delta time'', where ''delta'' is a jargon term in mathematics and related fields which means "difference" -- so a ''delta time'' is a time value which specifies the duration (or time difference) between two events.		The <tt>time</tt> value is a measurement of the time to wait between sending the <tt>message</tt> before that time and the <tt>message</tt> after that time. This method of specifying the time is called '''delta time'', where ''delta'' is a jargon term in mathematics and related fields which means "difference"—so a ''delta time'' is a time value which specifies the duration (or time difference) between two events.

	Note that MIDI messages usually come after each other rather quickly—especially if chords are played. So the predominant time between each MIDI message in a MIDI file will usually be small. This is the reason that VLVs are used to store MIDI-file timestamps, since they take up less space for small numbers.		Note that MIDI messages usually come after each other rather quickly—especially if chords are played. So the predominant time between each MIDI message in a MIDI file will usually be small. This is the reason that VLVs are used to store MIDI-file timestamps, since they take up less space for small numbers.

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:43:22Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:43, 15 January 2013
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	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. When space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. When space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, so the order of data in a MIDI file looks like this in one long stream:

	<ul>		<ul>

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:42:24Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:42, 15 January 2013
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	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. When space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:40:57Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:40, 15 January 2013
Line 3:		Line 3:
	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI ~~protocol~~ was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:40:34Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:40, 15 January 2013
Line 3:		Line 3:
	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. ~~The~~ MIDI protocol was created in the early 1980's when PC computers often didn't have hard disks, and ~~the floopy~~ disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. MIDI protocol was created in the early 1980's when personal computers often didn't have hard disks, and floppy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:

Craig at 22:38, 15 January 2013

2013-01-15T22:38:16Z

← Older revision		Revision as of 22:38, 15 January 2013
Line 1:		Line 1:
	Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI ~~files~~ VLVs can be 1–5 bytes long, depending on the size of the number it represents. MIDI VLVs always unpack into a four-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that ~~the~~ VLV continues to the next byte in the data, and a "0" bit indicates the end of ~~the~~ VLV.		Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. MIDI-file VLVs can be 1–5 bytes long, depending on the size of the number it represents. MIDI-file VLVs always unpack into a four-byte integer. The length of the VLV is controlled by the most-significant bit in each byte: a "1" bit indicates that a VLV continues to the next byte in the data, and a "0" bit indicates the end of a VLV.

	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited~~, so~~ MIDI-file timestamps were encoded as VLVs to save space. The MIDI protocol was created in the early 1980's when PC computers often didn't have hard disks, and the floopy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited and MIDI-file timestamps were encoded as VLVs to save space. The MIDI protocol was created in the early 1980's when PC computers often didn't have hard disks, and the floopy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:

Craig at 22:34, 15 January 2013

2013-01-15T22:34:42Z

← Older revision		Revision as of 22:34, 15 January 2013
Line 1:		Line 1:
	Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI files, VLVs can be 1–5 bytes long, depending on the size of the number it represents. MIDI VLVs always unpack into a four-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.		Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI files VLVs can be 1–5 bytes long, depending on the size of the number it represents. MIDI VLVs always unpack into a four-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.

	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

Craig at 22:34, 15 January 2013

2013-01-15T22:34:01Z

← Older revision		Revision as of 22:34, 15 January 2013
Line 1:		Line 1:
	Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI files, VLVs can be ~~stored in one through five~~ bytes, depending on the size of the number~~, and uncompress~~ into a 4-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.		Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI files, VLVs can be 1–5 bytes long, depending on the size of the number it represents. MIDI VLVs always unpack into a four-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.

	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

Craig at 22:31, 15 January 2013

2013-01-15T22:31:18Z

← Older revision		Revision as of 22:31, 15 January 2013
Line 1:		Line 1:
	Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet still able to handle larger integers. In MIDI files, VLVs can be stored in one through five bytes, depending on the size of the number, and uncompress into a 4-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.		Variable Length Values are an encoding system for multi-byte integers used to store timing information in [[standard MIDI files]]. They are a form of compression which minimizes storage for small integers, yet is still able to handle larger integers. In MIDI files, VLVs can be stored in one through five bytes, depending on the size of the number, and uncompress into a 4-byte integer. The length of the VLV is controlled by the most significant bit in each byte: a "1" bit indicates that the VLV continues to the next byte in the data, and a "0" bit indicates the end of the VLV.

	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

Craig: /* Motivation for Variable Length Values */

2013-01-15T22:28:11Z

Motivation for Variable Length Values

← Older revision		Revision as of 22:28, 15 January 2013
Line 3:		Line 3:
	== Motivation for Variable Length Values ==		== Motivation for Variable Length Values ==

	MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited, so MIDI-file timestamps were encoded as VLVs to save space. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.		MIDI files contain two basic components: (1) MIDI messages to be sent to a synthesizer and (2) the times when the messages will be sent to the synthesizer. When MIDI and MIDI files were initially designed, storage space on computers was limited, so MIDI-file timestamps were encoded as VLVs to save space. The MIDI protocol was created in the early 1980's when PC computers often didn't have hard disks, and the floopy disks could store 256KB. Timestamps in MIDI files are differential: they record the amount of time to wait since the previous message was sent. So in an active musical texture, many of the delta timestamps will be integers less than 128. These small numbers can be stored as single bytes VLVs, compared to four bytes if using a fixed-width integer. If space is at a premium, the 3-byte savings is useful; however with modern storage capabilities, the added encoding complexity becomes pointless.

	After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream:		After header information in MIDI files, the data consists of a list of events. Each event is composed of a timestamp followed by a MIDI message. These time/message pairs follow immediately after each other in a MIID file, os the order of data in a MIDI file looks like this in one long stream: