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Old 07 July 2015, 10:00   #46
Da Digger :)

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Join Date: Nov 2008
Location: Monza, Italy
Posts: 2,527
Originally Posted by Retro-Nerd View Post
Nope, still 240/288p. Hence the scanlines you can see due to half of the standard PAL/NTSC resolution. CRTs always supported progessive output.
Nope, I'm sure, and even the website you linked proves me right.
Here are the most important phrases:

All the classic videogame system (Mega Drive, SNES in standard mode, PC Engine, etc) as well as almost all 2D arcade games over the past two decades put out 15kHz RGB signals. A 15kHz signal (well, actually 15.75kHz, but nobody really cares) is called a 15khz signal because the cathode ray in your classic tube TV will cross the screen 15750 times horizontally per second.

If you take a 60Hz refresh rate (standard for arcade games and NTSC videogame systems) you just divide 15750 by 60 you'll see that your TV is able to produce 262 lines per 1/60 second this way. (per 1/60 sec means "per pass"). Taking away some front porch & back porch, you'll get your 220 to 240 which most videogames and arcade game have as their vertical resolution.

The horizontal resolution isn't really limited by the TVs horizontal scanrate, but most games systems are going for a 4:3 pixel ratio, so you end up with something like 320x240 pixels for classic arcade games.

As you can imagine 320x240 pixels is a rather low resolution for a TV signal (or DVD if you like). This is why TV signals are transmitted interlaced. This means that first all odd lines are drawn across the screen and then all even lines are drawn. This means you'll get 480 lines onscreen (instead of 240), but you'll have to live with a little flicker since the two adjacent lines aren't drawn directly after each other, but only alternating (in other words you still only get 240 lines per 1/60 sec).

This mode is called 15 kHz interlaced (640x480i).

The above for NTSC signals. For PAL signals it's 576i (interlaced).
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