Arclight: Redirected page to Y/C DUB color-under#Y/C-688

2026-02-07T03:11:36Z

Redirected page to Y/C DUB color-under#Y/C-688

← Older revision		Revision as of 03:11, 7 February 2026
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	~~'''Y/C-688''' is a color-under Y/C video signal format used on U-matic VTRs and some professional VHS equipment via DUB connectors. Like standard~~ [[~~S-Video (~~Y/C)]], the signal carries luminance (Y) and chrominance (C) on separate conductors, but the chrominance subcarrier remains at the color-under frequency of approximately 688 kHz (NTSC low-band) rather than being upconverted to the standard 3.58 MHz (NTSC) or 4.43 MHz (PAL) subcarrier.		#REDIRECT [[Y/C DUB color-under#Y/C-688]]

	~~== Overview ==~~

	During recording, U-matic and VHS-family formats downconvert the chrominance subcarrier to a lower frequency for storage on tape — a process known as color-under recording. On playback, the VTR's internal circuitry normally upconverts the chrominance back to the broadcast standard frequency before outputting composite or S-Video. The DUB ~~connector bypasses this upconversion step, providing the raw~~ color-under ~~signal directly.~~

	This approach preserves signal quality by avoiding an unnecessary decode/re-encode cycle, making it ideal for VTR-to-VTR dubbing and for feeding time base correctors that accept color-under input natively.

	~~== Color-Under Frequencies ==~~

	~~{\| class="wikitable"~~
	~~! Format !! Chrominance Frequency~~
	\|-
	~~\| U-matic low-band \|\| 685.546 kHz~~
	\|-
	~~\| U-matic hi-band / SP \|\| 983.803 kHz~~
	\|-
	~~\| VHS / VHS-C \|\| 629 kHz~~
	\|-
	~~\| S-VHS / S-VHS-C \|\| 629 kHz~~
	\|-
	~~\| Betamax \|\| 688 kHz~~
	\|-
	~~\| Video8 \|\| 732 kHz~~
	\|}

	~~Although "688" specifically refers to the approximate U-matic low-band and Betamax frequency, the term~~ Y/C-688 ~~is commonly used as a general label for color-under DUB connections on professional equipment, sometimes encompassing other color-under frequencies as well.~~

	~~== Connector ==~~

	The DUB signal is typically carried on a [[Hirose 7-pin DUB]] connector on U-matic equipment, or on a [[Mini-DIN-4]] connector on some professional VHS decks. Some time base correctors and transcoders (such as the [[Digital Processing Systems DPS-210]]) accept DUB input via [[BNC]] connectors with separate Y and C connections.

	~~== See Also ==~~

	* [[S-Video (Y/C)]] — Standard Y/C with upconverted chrominance
	* [[Hirose 7-pin DUB]] — Common connector for DUB signals
	* [[Composite (CVBS)]] — Composite video signal format

	~~[[Category:Video signal formats~~]]

Arclight-MCP-Bot: Create Y/C-688 signal format page for color-under DUB signals (via create-page on MediaWiki MCP Server)

2026-02-05T04:39:25Z

Create Y/C-688 signal format page for color-under DUB signals (via create-page on MediaWiki MCP Server)

New page

'''Y/C-688''' is a color-under Y/C video signal format used on U-matic VTRs and some professional VHS equipment via DUB connectors. Like standard [[S-Video (Y/C)]], the signal carries luminance (Y) and chrominance (C) on separate conductors, but the chrominance subcarrier remains at the color-under frequency of approximately 688 kHz (NTSC low-band) rather than being upconverted to the standard 3.58 MHz (NTSC) or 4.43 MHz (PAL) subcarrier.

== Overview ==

During recording, U-matic and VHS-family formats downconvert the chrominance subcarrier to a lower frequency for storage on tape — a process known as color-under recording. On playback, the VTR's internal circuitry normally upconverts the chrominance back to the broadcast standard frequency before outputting composite or S-Video. The DUB connector bypasses this upconversion step, providing the raw color-under signal directly.

This approach preserves signal quality by avoiding an unnecessary decode/re-encode cycle, making it ideal for VTR-to-VTR dubbing and for feeding time base correctors that accept color-under input natively.

== Color-Under Frequencies ==

{| class="wikitable"
! Format !! Chrominance Frequency
|-
| U-matic low-band || 685.546 kHz
|-
| U-matic hi-band / SP || 983.803 kHz
|-
| VHS / VHS-C || 629 kHz
|-
| S-VHS / S-VHS-C || 629 kHz
|-
| Betamax || 688 kHz
|-
| Video8 || 732 kHz
|}

Although "688" specifically refers to the approximate U-matic low-band and Betamax frequency, the term Y/C-688 is commonly used as a general label for color-under DUB connections on professional equipment, sometimes encompassing other color-under frequencies as well.

== Connector ==

The DUB signal is typically carried on a [[Hirose 7-pin DUB]] connector on U-matic equipment, or on a [[Mini-DIN-4]] connector on some professional VHS decks. Some time base correctors and transcoders (such as the [[Digital Processing Systems DPS-210]]) accept DUB input via [[BNC]] connectors with separate Y and C connections.

== See Also ==

* [[S-Video (Y/C)]] — Standard Y/C with upconverted chrominance
* [[Hirose 7-pin DUB]] — Common connector for DUB signals
* [[Composite (CVBS)]] — Composite video signal format

[[Category:Video signal formats]]

Y/C-688 - Revision history

Arclight: Redirected page to Y/C DUB color-under#Y/C-688

Arclight-MCP-Bot: Create Y/C-688 signal format page for color-under DUB signals (via create-page on MediaWiki MCP Server)