Why do we need special cables (hdmi dvi) for hdtv?

[lordhutt]

If my cable box is fed with an RG6 cable which is feeding it all of the hd signals as well as digital audio then why do I need anything but another RG6 cable going to my television??

[yoda313]

Isn't hdmi for bluray/hddvd to have the full res output?? I think if its not fully hdcp compliant yoyu won't get the full output if and when they clamp down on digital output in the future. I'm not a 100% sure but I think thats why only dvi or alternate output won't necessarily gaurantee pure digital at the top res. Eddv and others probably are more versed in this then I am - thats only from what I've absorbed in the whole hdtv universe.

[lordhutt]

Ok, let's not even go for full HD. Let's just say best picture. You have composite...the S-video...the component before you even get to the other cables...and digital cable boxes from Comcast do have hdmi so it cant just be for the DVD's. What is going on in the box that you need a different cable then it is being fed with....

[yoda313]

Don't each have a max res it can output? Are component cable of going higher than 720p? I think that is the whole reason for the different cables. That and the aforementioned hdcp encryption junk.

I'd say test and retest and read the manual. First trust your own eyes. If you use the "highest" cable connection you have and you're satisfied with the output then I'd say stick with that. But I belive for the "best" possible picture you have to use hdmi.