Generally, the signals from Cable TV can be received by the public antenna in new estates or buildings. Also, most television can also be tuned to the channels of Cable TV but the image colors are inverted. (Yellow become blue, black become white etc.)

After installing Cable TV, the antenna signal will pass through a decoder before connecting to VCR and TV. The decoder will filter out the frequency bands of Cable TV channels (in VHF) and decode one of the channels (selected by the decoder) to a certain frequency band in UHF. So, if you are a Cable TV subscriber, your VCR and TV can tune to that frequency to watch Cable TV.

Therefore, if you bypass the Cable TV decorder or you are not subscriber, you can use your television or VCR to scan through the VHF band and you can view most of the Cable TV channels with inverted color. However, due to the capability of different tuner, the sound may not be tuned properly. Fortunately, in our testing, we can tune to many channels including the Paid Movie Channels (HBO, Cineplex) and listen the sound of the channels.

In view of these, the only thing we need to do is to implement the color inverting to the video image in real time. DirectX 6.X can exactly do the task. And all we need is a video capture card to capture the video image into the computer and do the color invertion by using a DirectDraw filter.