PAR isn't used for display purposes. Display is determined by the video's Display Aspect Ratio (DAR), which tells the decoder what shape an entire Frame is. PAR is instead used for editing purposes, where image editing software often needs to know the shape of each pixel to produce a specific shape in the frame. For example, in order to draw a simple circle it's first necessary to determine how far apart each pixels is both horizontally and vertically, which can be determined by the PAR.
Some video stores a separate PAR value, in addition to a DAR for video decoders to use. Other times it must be calculated from reading the DAR first. You may be using editing software capable of this, but it's generally recommended to know your source video's PAR (or calculate it yourself) in order to double check any applications automatic settings.
Standard computer monitor resolutions use square pixels, as do standard HDTV resolutions. EDTV also uses square pixels, although digital SDTVs use pixels with the same PAR as NTSC or PAL DVDs.
Common PARs
Source | TV System | AR | Resolution | PAR |
---|---|---|---|---|
DVD | NTSC | 4:3 | 720x480 | 10:11 |
704x480 | 10:11 | |||
352x480 | 20:11 | |||
352x240 | 10:11 | |||
16:9 | 720x480 | 40:33 | ||
704x480 | 40:33 | |||
PAL | 4:3 | 720x576 | 59:54 | |
704x576 | 59:54 | |||
352x576 | 59:27 | |||
352x288 | 59:54 | |||
16:9 | 720x576 | 118:81 | ||
704x576 | 118:81 | |||
DV | NTSC | 4:3 | 720x480 | 10:11 |
PAL | 4:3 | 420x576 | 59:54 | |
SVCD | NTSC | 4:3 | 480x480 | 15:11 |
16:9 | 480x480 | 20:11 | ||
PAL | 4:3 | 480x576 | 59:36 | |
16:9 | 480x576 | 59:27 | ||
VCD | NTSC | 4:3 | 352x240 | 10:11 |
PAL | 4:3 | 352x576 | 59:54 |
Related Guides
Resizing DVD-Video To Square Pixels
Digital Video Fundamentals - Resolution and Aspect Ratio