NTSC to PAL convertor circuit (NTSC=>RGB; RGB=>PAL)

I want to make an NTSC to PAL colour convertor circuit.I dont want to change the 525 lines to 625 lines.I just need to change the color system.So, could anyone please post links of
1.An NTSC to RGB convertor circuit
2.and An RGB to PAL convertor circuit

Thanx
A.Pakhira


P.S:The parts should be readily available

There are several chips with application notes that philips makes that are digital video decoders which would output RGB, you could then take that digital output to a video encoder to generate your PAL signal. Micronas has a part that has both analog in and analog out, but I dont think it can take NTSC in and generate PAL output.

Well,could you please specify the names of some cheap ICs which do the jobs?