I was under the impression that auto aspect ratio (AR) switching was done under the control of the scart connector for an analog TV.

I can't see how it could be done any other way with an old CRT 16:9 TV (other than manual switching)

But I have just connected up an S-Video to S-Video lead from the S-Video socket of an STB to the front mounted S-Video socket on a Hitachi 16:9 CRT and auto AR switching is taking place with appropriate change of programme material.

ITV1 16:9 = TV is at 16:9, change channel to Sky Sports 4:3 and the TV auto detects and changes AR to 4:3 pillarbox

But how?!!

Surely this is impossible!

[technologist]

The answer is WSS widescreen switching- which is in the first half of line 23 that is not active picture. This is used on the Sky platform and can (sort of) be added by a set top box which works using AFD Active format descriptor.

Thanks for that info.

That must be it, just a bit surprising to have such technology on an 8 year old CRT.