Intro to Video Signals: Difference between revisions

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== Video Signals ==
{| class="wikitable"|-
{| class="wikitable"|-
! Video Standard
! Video Standard
! Image
! Image
! Description
! Connectors
! Signals Carried
! Explanation
! Explanation
|-
|-
| Radio Frequency (RF)
| Radio Frequency (RF)
| placeholder
| placeholder
| A screw-terminal connector, usually seen on pre-80's TVs and consoles.
| One F-type coax <br> OR <br> One RCA <br> OR <br> Two prongs
| Carries both audio and video, but is very low quality. Audio is only mono, and there is a lot of color banding and mixing.
| Luminance (Y, H, V), Chrominance (C), Audio Left, Audio Right
| RF (Radio Frequency) is a Frequency Modulated signal in the UHF band usually incoming from an antenna or long run cable. This signal contains modulated composite video and mono/stereo audio. It does a great job of transmitting a signal over very long distances over air or wire with little loss.
 
Most televisions feature an RF tuner and demodulator to handle RF input. The most common connector is the F-type (coax, like cable TV). Much older televisions (early 1980s and earlier) usually have two screws to fasten down a twin-lead antenna. Rarely they will have an RCA-type connector which expects RF input. Televisions with a rotary select dial usually indicates that it ''only'' supports RF input. Depending on the television, the RF tuner is usually connected to all inputs and may be designed to handle both 300 Ohm and 75 Ohm. The F-type connector is almost always expecting 75 Ohm input. Check the TV user guide or service manual to be sure. It will not harm the television to feed the wrong impedance, but the signal may be too weak to see.
 
If the impedance from your console to the TV is mismatched, you need a balun (transformer) – a very simple circuit and cheap to buy for less than $5 USD.
|-
|-
| Composite Video
| Composite Video
| placeholder
| placeholder
| Also called RCA, for the first company to make them, these typically come in sets of 2 or 3
| One RCA <br> OR <br> One BNC
| Composite video is very common, and comes on almost every consumer TV made after 1990. Much higher quality than RF.
| Luminance (Y, H, V), Chrominance (C)
| Composite video is very common, and comes on almost every consumer TV made after 1990. Composite, as the name implies, is a complex signal. It was designed for NTSC, PAL, and SECAM broadcasting and contains the information for chrominance (hue and saturation), luminance (brightness), horizontal sync, and vertical sync all on one wire.
 
While it is often downplayed as inferior to other video signal types, it remained a standard for which many CRTs and game consoles were designed to handle. The quirks and lossiness of the signal were sometimes exploited in games to create useful effects such as smoothed colour dithering and fake transparency. Examples [https://nerdlypleasures.blogspot.ca/2015/03/the-case-for-composite.html here on Genesis and SNES] ([https://nerdlypleasures.blogspot.ca/ nerdlypleasures.blogspot.ca]) and [https://www.youtube.com/watch?v=j-G02cjXpZ0 here with the transparent tubes in Sonic 2] ([https://www.youtube.com/ youtube.com]). On the other hand, visual defects such as [https://en.wikipedia.org/wiki/Dot_crawl dot crawl] and jitter can be a real nuisance of interference between the 5 signals. Many consumer TVs have a "comb filter" designed to eliminate interference issues, but often times professional or broadcast monitors do not have a comb filter as studios often wanted to be able to see interference issues and eliminate them during broadcast.
 
Composite supports up to 240p/480i resolution in NTSC and 288p/576i in PAL.
|-
|-
| S-Video
| S-Video
| placeholder
| placeholder
| Also called Y/C.
| One 4-pin Mini-DIN <br> OR <br> Two RCA <br> OR <br> Two BNC
| Usually uncommon in consoles until the mid-90s. This standard achieves better quality, because the signal is separated into y (luma, or black and white data) and C (chroma, or color data)
| Luminance (Y, H, V) <br> Chrominance (C)
| S-Video is derived from component video where Y retains the same level of fidelity along with synchronization signals, but the U &amp; V signals are [https://en.wikipedia.org/wiki/Quadrature_modulation quadrature modulated] and sent as one signal down the second wire.
 
S-video is considered a higher quality signal and is well supported by hardware from the mid 1990s and later.
 
* Supported by: SNES, PlayStation, PlayStation 2, Dreamcast, N64, Xbox, Phillips CDi.
* Easily Modded Consoles: Master System, Genesis, 32X, SNES Mini
|-  
|-  
| YPbPr
| Component YPbPr
| placeholder
| placeholder
| Commonly known as component video.
| Three RCA
| YPbPr splits video out to 3 different connectors, making it better quality than S-Video. These are Y (luma, same as S-Video, and Sync), Pb (the difference between Luma and blue), and Pr (the difference between Luma and red.) Green is unneeded, as it can be found using the information.  
| Luminance (Y, H, V) <br> Pb (blue difference from Y) <br> Pr (red difference from Y)
| YPbPr splits video out to 3 different connectors, making it better quality than S-Video. "Y" transmits brightness information (Luma) and horizontal/vertical sync, "Pb" transmits the difference between the blue color signal and Y, and "Pr" transmits the difference between the blue color signal and Y.
 
Component is a very high quality video signal derived from RGB. Transmission bandwidth (and storage) is reduced by a large margin via exploiting the limitations of human vision and relationships between colour attributes to its advantage. The formulae for deriving the weighted signals are as follows:
 
<pre>Y = 0.3R + 0.59G + 0.11B
U = 0.493(B - Y)
V = 0.877(R - Y)</pre>
Green information is not sent as it can be derived from these relationships.
 
There is also a similar YCbCr that is a digitally encoded.
 
* Supported by: Xbox, GameCube, PlayStation 2, PlayStation 3, Xbox 360, Wii. HD Retrovision cables perform conversion of RGB to Component.
 
|-
|-
| RGB
| RGB
| placeholder
| placeholder
| One SCART <br> OR <br> One JP-21 <br> OR <br> Three to Five RCA <br> OR <br> Three to Five BNC
| Uses different types of sync such as HV or Composite (not to be confused with composite sync!)
| Uses different types of sync such as HV or Composite (not to be confused with composite sync!)
| RGB is the best quality video you can get on a typical CRT, as it requires no transcoding or changing of the color space, since it is the same format that the electron gun uses to make the image displayed. RGB has many different standards for connectors that will be explained in the next table.
| RGB is the best quality video you can get, as it requires no transcoding or changing of the color space and it is the same format that the electron gun uses to make the image displayed for CRTs. Note that the difference between the sync separation types is often not noticeable, but the more separation the less chance of interference. Choose the most separated option which your equipment supports (depending on cable availability).
 
RGB (or RVB in France) is a shorthand for one of the following:
{| class="wikitable"
!width="25%"| Acronym
!width="25%"| Channels
!width="25%"| Description
!width="25%"| Supported Consoles
|-
| '''RGsB'''
| 3
| Sync on Green (SoG)
| PlayStation 2
|-
| '''RGBS (Composite Sync)'''
| 4
| RGB with Composite Sync (CSYNC) signal
| Mega Drive / Genesis 1 &amp; 2, SNES (NTSC), Neo Geo AES, Jaguar, Saturn, and PlayStation (with small mod)
|-
| '''RGBS (Sync on Luma)'''
| 4
| RGB with Luma as the sync signal. A sync stripper can be used to extract CSYNC from the luma signal.
| PlayStation, PlayStation 2, Dreamcast, N64, Xbox, SNES
|-
| '''RGBcvS'''*
| 4
| CSYNC over composite video (''c''omposite ''v''ideo ''S''ync). Also known as "sync on composite". A sync stripper can be used to extract CSYNC from the composite video signal.
| Xbox, PlayStation, SNES (PAL), Saturn (PAL), and GameCube (PAL)
|-
| '''RGBHV'''
| 5
| Independent sync (horizontal & vertical)
| Dreamcast
|}
|}




|}
== Connectors ==


{| class="wikitable"|-
{| class="wikitable"|-

Revision as of 04:08, 21 April 2022

Video Signals

Video Standard Image Connectors Signals Carried Explanation
Radio Frequency (RF) placeholder One F-type coax
OR
One RCA
OR
Two prongs
Luminance (Y, H, V), Chrominance (C), Audio Left, Audio Right RF (Radio Frequency) is a Frequency Modulated signal in the UHF band usually incoming from an antenna or long run cable. This signal contains modulated composite video and mono/stereo audio. It does a great job of transmitting a signal over very long distances over air or wire with little loss.

Most televisions feature an RF tuner and demodulator to handle RF input. The most common connector is the F-type (coax, like cable TV). Much older televisions (early 1980s and earlier) usually have two screws to fasten down a twin-lead antenna. Rarely they will have an RCA-type connector which expects RF input. Televisions with a rotary select dial usually indicates that it only supports RF input. Depending on the television, the RF tuner is usually connected to all inputs and may be designed to handle both 300 Ohm and 75 Ohm. The F-type connector is almost always expecting 75 Ohm input. Check the TV user guide or service manual to be sure. It will not harm the television to feed the wrong impedance, but the signal may be too weak to see.

If the impedance from your console to the TV is mismatched, you need a balun (transformer) – a very simple circuit and cheap to buy for less than $5 USD.

Composite Video placeholder One RCA
OR
One BNC
Luminance (Y, H, V), Chrominance (C) Composite video is very common, and comes on almost every consumer TV made after 1990. Composite, as the name implies, is a complex signal. It was designed for NTSC, PAL, and SECAM broadcasting and contains the information for chrominance (hue and saturation), luminance (brightness), horizontal sync, and vertical sync all on one wire.

While it is often downplayed as inferior to other video signal types, it remained a standard for which many CRTs and game consoles were designed to handle. The quirks and lossiness of the signal were sometimes exploited in games to create useful effects such as smoothed colour dithering and fake transparency. Examples here on Genesis and SNES (nerdlypleasures.blogspot.ca) and here with the transparent tubes in Sonic 2 (youtube.com). On the other hand, visual defects such as dot crawl and jitter can be a real nuisance of interference between the 5 signals. Many consumer TVs have a "comb filter" designed to eliminate interference issues, but often times professional or broadcast monitors do not have a comb filter as studios often wanted to be able to see interference issues and eliminate them during broadcast.

Composite supports up to 240p/480i resolution in NTSC and 288p/576i in PAL.

S-Video placeholder One 4-pin Mini-DIN
OR
Two RCA
OR
Two BNC
Luminance (Y, H, V)
Chrominance (C)
S-Video is derived from component video where Y retains the same level of fidelity along with synchronization signals, but the U & V signals are quadrature modulated and sent as one signal down the second wire.

S-video is considered a higher quality signal and is well supported by hardware from the mid 1990s and later.

  • Supported by: SNES, PlayStation, PlayStation 2, Dreamcast, N64, Xbox, Phillips CDi.
  • Easily Modded Consoles: Master System, Genesis, 32X, SNES Mini
Component YPbPr placeholder Three RCA Luminance (Y, H, V)
Pb (blue difference from Y)
Pr (red difference from Y)
YPbPr splits video out to 3 different connectors, making it better quality than S-Video. "Y" transmits brightness information (Luma) and horizontal/vertical sync, "Pb" transmits the difference between the blue color signal and Y, and "Pr" transmits the difference between the blue color signal and Y.

Component is a very high quality video signal derived from RGB. Transmission bandwidth (and storage) is reduced by a large margin via exploiting the limitations of human vision and relationships between colour attributes to its advantage. The formulae for deriving the weighted signals are as follows:

Y = 0.3R + 0.59G + 0.11B
U = 0.493(B - Y)
V = 0.877(R - Y)

Green information is not sent as it can be derived from these relationships.

There is also a similar YCbCr that is a digitally encoded.

  • Supported by: Xbox, GameCube, PlayStation 2, PlayStation 3, Xbox 360, Wii. HD Retrovision cables perform conversion of RGB to Component.
RGB placeholder One SCART
OR
One JP-21
OR
Three to Five RCA
OR
Three to Five BNC
Uses different types of sync such as HV or Composite (not to be confused with composite sync!) RGB is the best quality video you can get, as it requires no transcoding or changing of the color space and it is the same format that the electron gun uses to make the image displayed for CRTs. Note that the difference between the sync separation types is often not noticeable, but the more separation the less chance of interference. Choose the most separated option which your equipment supports (depending on cable availability).

RGB (or RVB in France) is a shorthand for one of the following:

Acronym Channels Description Supported Consoles
RGsB 3 Sync on Green (SoG) PlayStation 2
RGBS (Composite Sync) 4 RGB with Composite Sync (CSYNC) signal Mega Drive / Genesis 1 & 2, SNES (NTSC), Neo Geo AES, Jaguar, Saturn, and PlayStation (with small mod)
RGBS (Sync on Luma) 4 RGB with Luma as the sync signal. A sync stripper can be used to extract CSYNC from the luma signal. PlayStation, PlayStation 2, Dreamcast, N64, Xbox, SNES
RGBcvS* 4 CSYNC over composite video (composite video Sync). Also known as "sync on composite". A sync stripper can be used to extract CSYNC from the composite video signal. Xbox, PlayStation, SNES (PAL), Saturn (PAL), and GameCube (PAL)
RGBHV 5 Independent sync (horizontal & vertical) Dreamcast


Connectors

Video Connector Image Description
Coax F-Connector placeholder Usually used for RF. Also sometimes in the form of a brown or orange RCA jack similar to composite.
RCA placeholder Most commonly used for composite but can sometimes be used for S-Video (labelled Y and C) or RF (if orange, black, or brown). Also used for component video (YPbPr or RGB).
BNC placeholder Generally found on professional displays and are used as a more secure RCA jack. Also often carry RGB signals.
SCART placeholder Can carry Composite, S-Video, and RGB signals, along with audio. Very common in Europe.
JP-21 placeholder Identical in appearance to SCART but the pinout is different. Generally only found in Japan or Asia. Not compatible with SCART.
VGA placeholder VGA is an RGBHV standard that uses a 15-pin D-Sub connector, usually used on computers, PC monitors, and presentation TVs.