Why is there PAR's

[PhantomVideo]

Hi there, I understand what Pixel Aspect Ratio is and what formats use it,
but why do they use it ?, why dont mini dv roll at a raster of 768x576 (pal)
and why is DVCPROHD 960x720 in stead of 1280x720 ?

[Barry_Green]

It's another form of compression. There are many ways that a video signal gets compressed, including interframe compression (long-GOP), DCT compression (the so-called 5:1 compression ratio of DV), prefiltering (pixel aspect ratios), and color sampling (4:2:2 instead of 4:4:4, or, even worse, 4:2:0 or 4:1:1). They're all ways of reducing the bandwidth or data rate.

[PhantomVideo]

thanks barry :)