Originally Posted by fhall1
Read about scan lines.....although the "i" and "p" formats have the same number of pixels, the "i" (interlaced) images only contain half the scan lines of a "p" (progressive) image....that's why the "i" looks crappier.
That's not really it.
The interlacing happens so fast, you wouldn't really see the difference. At the same frame rate, the only gain of p over i is the lack of interlacing artifacts when things move fast. Things only look crisper in progressive formats if the frame rate is higher.
The real reasons are these:
1) Cable and satellite whack the heck out of SD video with compression - way more than DVD has. That's why it looks so muddy.
2) Cable and satellite SD isn't actually 480i. It's shaved down to about 350-380i. That's why things look do jagged. You're missing 1/4 the resolution.
So, less resolution + more compression than DVD = worse quality.
I work with archived 480i video in professional TV all the time. It blows away DVD because I'm seeing it before the compression the same video on DVD would have. It definitely looks far better than cable or satellite SD. Likewise, the HD I work with looks amazing compared to what you see at home - even on Blu-ray.
It all comes down to how much messing around has occurred before it gets to the viewer.