captureing cable tv with a composite input?

[think_harder]

I have a Nvidia WDM universal video capture card in my computer, and was wondering if it would be possible to capture from coaxial cable using an adaptor for my composite input... or would I have to buy a cable box/vcr to output to individual video and audio vcr cables? I was thinking of buying a tv tuner but didn't want to spend the extra 50 dollers

is there software available that configures a composite input to scan the analog stream for different channels and watch the video/audio, or am I better off buying an aver media tv tuner and disableing my current card?

[avih]

composite input will NOT handle rf-input, a tuner must be present for that to happen. this is because the audio/video signals are modulated onto the rf carrier signal. composite input expects 'pure' (=unmodulated) video signal.

if you don't have a vcr or cable box that outputs composite video/audio, then composite input is useless for u.