SCART is a European standard for connecting audio-visual equipment together. Different methods of transmitting video such as composite, Y/C (S-video) and RGB are supported on the same cable. The RGB method of transmission is of particular interest as it uses Red, Green, Blue and Composite Sync pins, which is very close to the way signal is carried over a VGA cable, Red, Green, Blue, Horizontal Sync and Vertical Sync. This makes is possible to adapt a VGA output to drive a RGB-capable SCART television directly.
Driving a TV directly has some advantages. The quality is superior to composite or S-video, and as the video card's TV encoder is completely bypassed, custom resolutions and refresh rates can be programmed. On the down side, this method can require some experimentation to get right.
As these types of cables are directly driving the television, there exists potential for damage through mistakes in cabling or even sending an out-of-spec signal to the television. Consider yourself warned and proceed at your own risk.
- A television with an RGB capable SCART socket. Just the presence of a SCART socket does not mean the television accepts RGB. Check the manual.
- A video card capable of supporting interlaced resolutions.
- A video card capable of supporting a very low dot-clock frequency (14.76 MHz for PAL, 13.34 MHz for NTSC.)
These fall into two groups. Some Radeon video cards are capable of generating composite sync directly and therefore need only a simple cable connecting the pins together. All other cards require a small circuit to convert the horizontal/vertical sync into composite sync. You can tell the circuits apart by the because the more complex version will have at least one transistor.
|Name||Interlacing?||<15 MHz dot clock?|
|GeForce 4 integrated video||YES||YES|
|Radeon 8000 series|
|Radeon 9000 series|
|Via Unichrome IGP|
Here are some links to information on how to convert the VGA out signal to a suitable signal for a RGB Scart input.