What do you mean by "scanlines/interlacing"? What are scanlines? What is interlacing?
It can.. PAL and NTSC have fairly complex information on them and for example NTSC has an odd number of scanlines (525) this means 262 1/2 scanlines for each vertical pulse. To actually have a complete frame it takes 4 vertical pulses (called a super frame).
I don't quite understand. What causes the black lines? Are all the odd lines updated and all of the even lines are left black and then on the next refresh all of the even lines are updated and all of the odd lines are left black? What is the purpose of interlacing? Is there an advantage at having a faster frame rate even though it's just showing different parts of the same image (odd and even lines). Is the way I understood interlacing to work correct at all :-?
Interlacing is/was used to increase the viewable image size on a limited bandwidht signal. Look at what is happening inside a normal television. A signal is sent then recieved by the TV. The TV converts the signal in real time into RGB data and puts it to the screen. Thus the signal is actively driving your display. This is important to remember that in order to maintain an image on a CRT you have to continously refresh the data. NTSC uses 2 fields to form a basic sub frames this gives the perception of having more data available even though there isn't. The CRT's phospher's decay after being excited by an electron beam. It takes roughly 1/60th of a second. It maintains an image by using your brain persistance of vision. So the image is semi static on an older TV.
