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