RGBS: Difference between revisions

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'''RGBS''' (RGB + composite Sync) is an analog video signal format that transmits the red, green, and blue color channels on three separate 75Ω lines, plus a fourth line carrying composite synchronization (a combined horizontal and vertical sync signal). RGBS is widely considered the highest-quality standard-definition analog video format, as it sends color information directly to the display without any encoding, compression, or multiplexing — the display receives exactly the color data it needs to drive its electron guns (in the case of a CRT) with no decoding step required.

== Overview ==

All CRT displays ultimately drive their electron guns using red, green, and blue signals. In most consumer video formats ([[Composite (CVBS)]], [[S-Video (Y/C)]], [[Component (YPbPr)|YPbPr]]), the original RGB picture is encoded into a more compact representation for transmission, then decoded back to RGB inside the display. Each encoding/decoding step introduces potential artifacts and signal loss. RGBS bypasses this entirely by transmitting the original RGB signals directly, requiring only a sync signal to coordinate the display's scanning.<ref name="wp-component">[https://en.wikipedia.org/wiki/Component_video "Component video"], Wikipedia.</ref>

RGBS is technically a form of "component video" (since it uses separate signal components), but in consumer electronics the term "component video" almost always refers to [[Component (YPbPr)|YPbPr]]. To avoid confusion, the retro gaming and professional video communities use "RGB" or "RGBS" specifically.

== Sync Methods ==

The "S" in RGBS refers to composite sync (csync), but in practice several different signals can provide the synchronization information alongside RGB. The most common sync variants are:<ref name="retrorgb-sync">[https://retrorgb.com/sync.html "Sync"], RetroRGB.</ref>

* '''Composite sync (csync)''' — a dedicated sync-only signal combining horizontal and vertical sync pulses into a single clean waveform. This is the "purest" sync type and is compatible with virtually all RGB-capable displays. Proper csync is a 75Ω signal, typically requiring a sync stripper or voltage divider circuit if derived from a TTL-level source.

* '''Sync on composite video (cvbs)''' — uses a full [[Composite (CVBS)|composite video]] signal as the sync source. The display extracts only the sync pulses and ignores the color/luminance information. This is the most common and safest approach in [[SCART]] cables for game consoles. The downside is that poorly shielded cables can allow the composite video's color subcarrier to interfere with the RGB signals, producing a visible checkerboard pattern.

* '''Sync on luma''' — uses the Y (luminance) signal from [[S-Video (Y/C)|S-Video]] as the sync source. This avoids the checkerboard issue of composite sync-on-video since the luma signal has no color subcarrier, while remaining safe voltage-wise.

* '''Sync on green (RGsB)''' — the sync signal is embedded within the green channel itself, reducing the connection to three wires. Used by some Sony professional equipment and the PlayStation 2. Most consumer displays that accept RGBS cannot handle sync-on-green without additional circuitry.

A related but distinct format is '''RGBHV''', which separates horizontal and vertical sync onto two individual wires (five wires total). This is the standard used by VGA computer monitors and is commonly found on multi-sync professional monitors. RGBHV is not directly compatible with RGBS without a sync combiner.

== Specifications ==

{| class="wikitable"

! Parameter !! Value

|-

| Signal type || Four-channel analog (R, G, B + sync)

|-

| R/G/B signal level || 0.7V peak-to-peak, 75Ω impedance

|-

| Composite sync level || 0.3V (within composite video) or TTL (0–5V, requires attenuation)

|-

| Impedance || 75Ω per channel

|-

| Supported resolutions || 240p, 480i, 576i (15 kHz); 480p, 576p (31 kHz with compatible display)

|-

| Common connectors || [[SCART]] (Europe), [[JP21]] (Japan), [[BNC]] ×4 (professional), [[RCA (connector)|RCA]] ×4 (modified consumer equipment)

|-

| Standards || EN 50049-1 (via SCART), EIAJ CPR-1201 (via JP21)

|}

== Connectors ==

RGBS is carried over several different connector types depending on the region and equipment class:

* '''[[SCART]]''' — the primary consumer RGB connector in Europe. SCART carries RGBS alongside composite video and stereo audio in a single 21-pin connector. RGB mode is activated by applying 1–3V to pin 16 (blanking/fast switching). The sync signal rides on pin 20 (composite video input).

* '''[[JP21]]''' — the Japanese equivalent of SCART, using an identical 21-pin physical connector but with a completely different and incompatible pinout. JP21 carries RGBS and is found on Japanese equipment such as the Sony Profeel series and various Japanese game console cables.

* '''[[BNC]] ×4''' — professional monitors (Sony PVM/BVM, JVC TM, Ikegami, NEC MultiSync) use four separate BNC connectors for R, G, B, and sync. This provides the best signal integrity and is the standard in broadcast and post-production environments.

* '''[[RCA (connector)|RCA]] ×4''' — some consumer equipment and RGB-modified CRT televisions use four RCA jacks. This is less common than SCART or BNC but is encountered on some monitors and RGB mod installations.

* '''DE-15 (VGA/HD-15)''' — carries RGBHV (separate H and V sync) rather than RGBS, but some multi-sync monitors accept both formats. Adapters or sync combiners may be needed.

== Use on CRT Equipment ==

=== Professional Monitors ===

RGBS (via BNC) is the standard video input on professional CRT monitors such as the Sony PVM and BVM series, JVC TM series, Ikegami TM series, and NEC MultiSync monitors. These monitors are prized in the retro gaming community for their excellent image quality, precise color reproduction, and support for 240p signals. Professional monitors typically accept RGBS alongside [[Composite (CVBS)|composite]], [[S-Video (Y/C)|S-Video]], and sometimes [[Component (YPbPr)|component]] inputs.

=== European Consumer Televisions ===

Most European CRT televisions from the 1980s onward accept RGB via [[SCART]], making RGB the default high-quality connection for game consoles, computers, and satellite receivers across Europe. European game console cables (for systems like the Super Nintendo, Mega Drive, PlayStation, Saturn, and Dreamcast) commonly use SCART for RGB output, giving European consumers access to significantly better image quality than the composite or S-Video connections typical in North America and Japan.

=== Japanese Equipment ===

In Japan, RGB input via [[JP21]] was available on certain high-end consumer monitors and televisions (notably the Sony Profeel/Profeel Pro series), but never achieved the universal adoption that SCART enjoyed in Europe. Japanese game consoles do output RGB natively in most cases, but consumers typically required specific JP21 cables.

=== RGB-Modified Consumer TVs ===

In North America, where consumer CRT televisions generally lack factory RGB inputs, enthusiasts commonly perform "RGB mods" — modifications that tap into the TV's internal video processing chip (jungle IC) to inject external RGBS signals. This bypasses the TV's composite or S-Video decoding entirely, providing professional-monitor-quality images on consumer hardware.<ref name="retrorgb-mod">[https://admin.retrorgb.com/the-a-to-z-of-rgb-modding-a-crt.html "The A to Z of RGB Modding a CRT"], RetroRGB.</ref>

== Quality Comparison ==

In the hierarchy of common analog video connections on CRT televisions (worst to best):

# '''[[RF (F-type)|RF]]''' — modulated signal; lowest quality

# '''[[Composite (CVBS)]]''' — combined luminance and chrominance; dot crawl, cross-color

# '''[[S-Video (Y/C)]]''' — separated luminance and chrominance; cleaner than composite

# '''[[Component (YPbPr)]]''' — fully separated three-channel signal; near-RGB quality

# '''[[RGBS|RGB]]''' — direct red/green/blue signals; theoretically optimal

At standard-definition resolutions (240p/480i/576i), the practical difference between RGBS and [[Component (YPbPr)|YPbPr]] is minimal, as both fully separate color information. The theoretical advantage of RGBS is that it requires no matrix conversion (the display receives R, G, B directly), while YPbPr requires a matrix operation to recover RGB — but modern displays perform this conversion with negligible loss.

The primary practical advantage of RGB for retro gaming is that most classic game consoles output native RGBS (since their video chips generate RGB internally), while YPbPr component video requires either native console support (limited to 6th-generation and later consoles) or an external RGB-to-YPbPr transcoder.

== See Also ==

* [[Component (YPbPr)]] — Three-channel luminance/chrominance analog video

* [[Composite (CVBS)]] — Single-channel analog video

* [[S-Video (Y/C)]] — Two-channel analog video

* [[SCART]] — European 21-pin connector commonly carrying RGBS

* [[JP21]] — Japanese 21-pin connector carrying RGBS (incompatible with SCART)

* [[BNC]] — Professional connector used for RGBS on PVM/BVM monitors

== References ==

[[Category:Video signal formats]]

@@ Line 1: / Line 1: @@
+'''RGBS''' (RGB + composite Sync) is an analog video signal format that transmits the red, green, and blue color channels on three separate 75Ω lines, plus a fourth line carrying composite synchronization (a combined horizontal and vertical sync signal). RGBS is widely considered the highest-quality standard-definition analog video format, as it sends color information directly to the display without any encoding, compression, or multiplexing — the display receives exactly the color data it needs to drive its electron guns (in the case of a CRT) with no decoding step required.
+== Overview ==
+All CRT displays ultimately drive their electron guns using red, green, and blue signals. In most consumer video formats ([[Composite (CVBS)]], [[S-Video (Y/C)]], [[Component (YPbPr)|YPbPr]]), the original RGB picture is encoded into a more compact representation for transmission, then decoded back to RGB inside the display. Each encoding/decoding step introduces potential artifacts and signal loss. RGBS bypasses this entirely by transmitting the original RGB signals directly, requiring only a sync signal to coordinate the display's scanning.<ref name="wp-component">[https://en.wikipedia.org/wiki/Component_video "Component video"], Wikipedia.</ref>
+RGBS is technically a form of "component video" (since it uses separate signal components), but in consumer electronics the term "component video" almost always refers to [[Component (YPbPr)|YPbPr]]. To avoid confusion, the retro gaming and professional video communities use "RGB" or "RGBS" specifically.
+== Sync Methods ==
+The "S" in RGBS refers to composite sync (csync), but in practice several different signals can provide the synchronization information alongside RGB. The most common sync variants are:<ref name="retrorgb-sync">[https://retrorgb.com/sync.html "Sync"], RetroRGB.</ref>
+* '''Composite sync (csync)''' — a dedicated sync-only signal combining horizontal and vertical sync pulses into a single clean waveform. This is the "purest" sync type and is compatible with virtually all RGB-capable displays. Proper csync is a 75Ω signal, typically requiring a sync stripper or voltage divider circuit if derived from a TTL-level source.
+* '''Sync on composite video (cvbs)''' — uses a full [[Composite (CVBS)|composite video]] signal as the sync source. The display extracts only the sync pulses and ignores the color/luminance information. This is the most common and safest approach in [[SCART]] cables for game consoles. The downside is that poorly shielded cables can allow the composite video's color subcarrier to interfere with the RGB signals, producing a visible checkerboard pattern.
+* '''Sync on luma''' — uses the Y (luminance) signal from [[S-Video (Y/C)|S-Video]] as the sync source. This avoids the checkerboard issue of composite sync-on-video since the luma signal has no color subcarrier, while remaining safe voltage-wise.
+* '''Sync on green (RGsB)''' — the sync signal is embedded within the green channel itself, reducing the connection to three wires. Used by some Sony professional equipment and the PlayStation 2. Most consumer displays that accept RGBS cannot handle sync-on-green without additional circuitry.
+A related but distinct format is '''RGBHV''', which separates horizontal and vertical sync onto two individual wires (five wires total). This is the standard used by VGA computer monitors and is commonly found on multi-sync professional monitors. RGBHV is not directly compatible with RGBS without a sync combiner.
+== Specifications ==
+{| class="wikitable"
+! Parameter !! Value
+|-
+| Signal type || Four-channel analog (R, G, B + sync)
+|-
+| R/G/B signal level || 0.7V peak-to-peak, 75Ω impedance
+|-
+| Composite sync level || 0.3V (within composite video) or TTL (0–5V, requires attenuation)
+|-
+| Impedance || 75Ω per channel
+|-
+| Supported resolutions || 240p, 480i, 576i (15 kHz); 480p, 576p (31 kHz with compatible display)
+|-
+| Common connectors || [[SCART]] (Europe), [[JP21]] (Japan), [[BNC]] ×4 (professional), [[RCA (connector)|RCA]] ×4 (modified consumer equipment)
+|-
+| Standards || EN 50049-1 (via SCART), EIAJ CPR-1201 (via JP21)
+|}
+== Connectors ==
+RGBS is carried over several different connector types depending on the region and equipment class:
+* '''[[SCART]]''' — the primary consumer RGB connector in Europe. SCART carries RGBS alongside composite video and stereo audio in a single 21-pin connector. RGB mode is activated by applying 1–3V to pin 16 (blanking/fast switching). The sync signal rides on pin 20 (composite video input).
+* '''[[JP21]]''' — the Japanese equivalent of SCART, using an identical 21-pin physical connector but with a completely different and incompatible pinout. JP21 carries RGBS and is found on Japanese equipment such as the Sony Profeel series and various Japanese game console cables.
+* '''[[BNC]] ×4''' — professional monitors (Sony PVM/BVM, JVC TM, Ikegami, NEC MultiSync) use four separate BNC connectors for R, G, B, and sync. This provides the best signal integrity and is the standard in broadcast and post-production environments.
+* '''[[RCA (connector)|RCA]] ×4''' — some consumer equipment and RGB-modified CRT televisions use four RCA jacks. This is less common than SCART or BNC but is encountered on some monitors and RGB mod installations.
+* '''DE-15 (VGA/HD-15)''' — carries RGBHV (separate H and V sync) rather than RGBS, but some multi-sync monitors accept both formats. Adapters or sync combiners may be needed.
+== Use on CRT Equipment ==
+=== Professional Monitors ===
+RGBS (via BNC) is the standard video input on professional CRT monitors such as the Sony PVM and BVM series, JVC TM series, Ikegami TM series, and NEC MultiSync monitors. These monitors are prized in the retro gaming community for their excellent image quality, precise color reproduction, and support for 240p signals. Professional monitors typically accept RGBS alongside [[Composite (CVBS)|composite]], [[S-Video (Y/C)|S-Video]], and sometimes [[Component (YPbPr)|component]] inputs.
+=== European Consumer Televisions ===
+Most European CRT televisions from the 1980s onward accept RGB via [[SCART]], making RGB the default high-quality connection for game consoles, computers, and satellite receivers across Europe. European game console cables (for systems like the Super Nintendo, Mega Drive, PlayStation, Saturn, and Dreamcast) commonly use SCART for RGB output, giving European consumers access to significantly better image quality than the composite or S-Video connections typical in North America and Japan.
+=== Japanese Equipment ===
+In Japan, RGB input via [[JP21]] was available on certain high-end consumer monitors and televisions (notably the Sony Profeel/Profeel Pro series), but never achieved the universal adoption that SCART enjoyed in Europe. Japanese game consoles do output RGB natively in most cases, but consumers typically required specific JP21 cables.
+=== RGB-Modified Consumer TVs ===
+In North America, where consumer CRT televisions generally lack factory RGB inputs, enthusiasts commonly perform "RGB mods" — modifications that tap into the TV's internal video processing chip (jungle IC) to inject external RGBS signals. This bypasses the TV's composite or S-Video decoding entirely, providing professional-monitor-quality images on consumer hardware.<ref name="retrorgb-mod">[https://admin.retrorgb.com/the-a-to-z-of-rgb-modding-a-crt.html "The A to Z of RGB Modding a CRT"], RetroRGB.</ref>
+== Quality Comparison ==
+In the hierarchy of common analog video connections on CRT televisions (worst to best):
+# '''[[RF (F-type)|RF]]''' — modulated signal; lowest quality
+# '''[[Composite (CVBS)]]''' — combined luminance and chrominance; dot crawl, cross-color
+# '''[[S-Video (Y/C)]]''' — separated luminance and chrominance; cleaner than composite
+# '''[[Component (YPbPr)]]''' — fully separated three-channel signal; near-RGB quality
+# '''[[RGBS|RGB]]''' — direct red/green/blue signals; theoretically optimal
+At standard-definition resolutions (240p/480i/576i), the practical difference between RGBS and [[Component (YPbPr)|YPbPr]] is minimal, as both fully separate color information. The theoretical advantage of RGBS is that it requires no matrix conversion (the display receives R, G, B directly), while YPbPr requires a matrix operation to recover RGB — but modern displays perform this conversion with negligible loss.
+The primary practical advantage of RGB for retro gaming is that most classic game consoles output native RGBS (since their video chips generate RGB internally), while YPbPr component video requires either native console support (limited to 6th-generation and later consoles) or an external RGB-to-YPbPr transcoder.
+== See Also ==
+* [[Component (YPbPr)]] — Three-channel luminance/chrominance analog video
+* [[Composite (CVBS)]] — Single-channel analog video
+* [[S-Video (Y/C)]] — Two-channel analog video
+* [[SCART]] — European 21-pin connector commonly carrying RGBS
+* [[JP21]] — Japanese 21-pin connector carrying RGBS (incompatible with SCART)
+* [[BNC]] — Professional connector used for RGBS on PVM/BVM monitors
+== References ==
+<references />
 [[Category:Video signal formats]]