On Tue, Jul 17, 2012 at 10:03 AM, Kilian Zott <kil...@diezotts.de> wrote: > thats a strange comparison since usb is a serial bus > vga is not even digital, so how can you talk about throughput? lol
Information doesn't need to be digital. Terms like 'bandwidth' really do apply. VGA does place some structure on its signal. You have a vertical and horizontal refresh rates. Your vertical refresh rate is usually in the 10s of Hz. I've seen displays range from 56Hz (terrible, terrible flicker on CRTs) to 120Hz (smooth as glass). Your horizontal refresh rates are usually in the 10s of *KHz*. The combination of the two dictated how many scanlines you could fit into your signal. Your number of pixels in a line was (in reality) limited by your video card's dot clock, but you might adjust things if you preferred, e.g. square pixels instead of whatever the per-pixel aspect ratio normally was. (I really don't rememeber.) Unlike DVI and HDMI, which support pixel formats that have subsampling, VGA didn't have any kind of compression mechanism. You had three channels, red, green and blue, and their voltage levels on the wire controlled the brightness of that color at whatever particular point on the display corresponded to that instant in your horizontal and vertical sweeps. If you'd like to know how I compare USB and VGA, look at ways VGA and DVI are analogous. Of course, under certain (now very unusual) circumstances, VGA can kick DVI's butt. -- :wq
