Request: Video Signal and connectors howto sticky

[ikonia]

could someone in the know make a straight forward summery sticky thread on all the connectors/techniques

eg: composite, component, scart, svideo, rgb, etc etc.

Other forum areas have really found benifit from a good sticky outlining the basics of some technologies.

I for one would find it useful and appriciate a guide on all the audio/visual techniques and connectors.

the digital sound one is a good example.

[Alex]

Hmmm, I may be able to do something basic later about them and their respective benefits - don't expect too much though!

[ikonia]

I'd find it very helpful personally.

thank you

[Alex]

LOL, see below (or above, depending...)

See here for new thread on this topic

[TheAnimus]

Analouge Video.

Analouge video works by seperating out the signals into 'lines' of video data. This is because the old fasioned TVs consisted of cathode ray tubes which had to be swung back to the start of the next line (like a carriage return on a type writer). Some forms of analouge can carry more lines than others, this improves the resolution.

The colour in the video signal depends a lot on the standards used. The best available been descrete Red, Green and Blue luminosity.

SCART (aka Euro Conector) is one plug fits all method of connecting equipment, a scart plug dosen't mean it supports all 'standards', as a lot has been added since the original scart standard, the following analouge can all be carried by scart.

Composite:
Crap. (uses 'frequency division' multiplexing, often has 'blurry' around the edges, its too late to remeber my a-level stuff properly)
S-Video:
Slightly less crap than composite, uses seperate signal lines. (Luma and Chrona)

Component:
Often miss understood, there are lots of ways of transmitting the the video using this standard. RGB is a type of component, generally only found in SCART leads, each colour channel has its own luminance level. Simple! This tends to be limited to 480p

YPbPr is the other main component video standard, this is found in everyday products upto 1080p. Y is luminance, Pb is the difference in Blue, Pr the difference in Red. From this RGB can be constructed, but also high quality black and white information. YPbPr is very popular with digital image standards hence why its on most DVD players (as the MPEG decoding is simple for this). Most DVD players can now choose between YPbPr and RGB, often YPbPr is refered too as Component video or RCA because it is output on a Red Green and Blue RCA conector. Even thou its outputting YPbPr, confusing!

[TheAnimus]

Digital Video.

Digital video is what makes sense when using TFTs and Plasmas. As most of the analouge signals where designed with CRTs firmly in mind!

HDMI is the main standard at the moment so its all i will talk about, you can convert regular DVI as used by computers to HDMI with mearly a cable, that should cost no more than £10.

HDMI like most digital signal standards is devided into channels.

These channels can carry information, for this thread i'm going to ignore the audio and control channels, only look at the Video channel.

DVI-D and DVI-I are the standards used by HDMI for its video channel data. These can be thought of as tried and tested. They are designed for short length runs, thou no standard is mention (that i've read anyway) its a good thought as 5m been about the 'right' length, with it running to 10m before active extendors should be considered.

DVI provides high quality 24bit colour information, this can be extended by using dual link. But seriously, at present this just isn't worth doing. Its still like the analouge transmission of lines, but this time each column (or pixel) is determinable. This means you can run at the native pixel clock perfectly. That leads too good picture quality.

[TheAnimus]

Cable quality.

Analouge.
Can make a difference, the main problem is sheilding, different signals interfearing with each other. The conductor generally isn't a problem, its all about the sheilding. There are expensive cables out here, but most of them are designed by evil marchictecture feinds, and have no technical benefit. Whilst silver is a better conductor, your TV and hifi WILL NOT be using it, as it is simply not needed for the really not that complicated signals that are been used.

Gold, generally this is used for the plugs, which is often accepted to improve the conductivity. But there is no point having a solid gold cable!

Digital.
The cheapest one that works, will give the same picture as the one the idoits buy. No, their image isn't crisper, their lieing. If i'd paid £80 for snake oil i'd feal like pretending it was real too.

[herulach]

Analouge Video.

Analouge video works by seperating out the signals into 'lines' of video data. This is because the old fasioned TVs consisted of cathode ray tubes which had to be swung back to the start of the next line (like a carriage return on a type writer). Some forms of analouge can carry more lines than others, this improves the resolution.

Analogue Video:

Analogue is a commonly misspelled word

Computer monitors also use RGB signals, and as such it is fairly simple to hack together a D-Sub to SCART adaptor, using 4 resistors, a transistor and a steady hand with a soldering iron. (link)

The reverse isnt as easy, and a such youre probably best off buying a box to do all the trickery for you.


And on a not strictly related to the original question, but still relevant:

Coaxial Cable (I.E. TV antenna/sky/ntl)

TV Antennas use bog standard coax cable, which can be picked up by the reel from B&Q (usually only the warehouse ones), Maplin etc. This is fine and dandy, however, it can pose some problems if its pretty old, should you be having trouble picking up a digital signal through your aerial, it is more than likely the cable, not the aerial that needs changing (its certainly a damn sight cheaper to at least try the cable). While youre at it, run higher grade (usually labelled ft/ct100) cable this has better shielding and as such will perform better on long runs, as there will be les signal loss, especially important if you use non amplified splitters.

Satellite/Cable
This is easy to run yourself, again use the higher grade cable , as its needed for these signals. If youre making your won ends, they are fairly easy to fit, provided you dont buy crimp on ones, and female-female adaptors are readily available.