problems understanding SAR/PAR/DAR

[rekotc]

hello everybody, i have a "simple" question, i studied the different definitions on SAR PAR and DAR using wikipedia and other websites but i cant understand them 100%. here is an example of my problem:

SAR × PAR = DAR.

this is the starting point, for what i know DAR is for example 16:9, PAR in case of PAL format is 118:81 if it's widescreen (16:9), so if i have a source with a resolution of 720×576 (so SAR is 1,25) i should find the DAR value by simply doing (following the above equation):

1,25*(118:81) = DAR..right?

in this case i expect DAR to be equal to 16:9 so = 1,7..but it doesnt happen..what am i missing here?

thanks in advance

[intracube]

Although the resolution is 720x576, only the central 702x576 pixels are used to contain the 16:9 image.

Therefore the 720x576 image is slightly wider than 16:9:
http://en.wikipedia.org/wiki/Overscan#720_vs._702_or_704

702/576 = 1.21875
1.21875*(118/81) = ~1.78

[rekotc]

great!!..thanks for this last detail ..i really was losing my mind on it!..thanks grazie!

[intracube]

You're welcome

[aedipuss]

widescreen pal 720x576 is 1024x576 in square pixel format if that's what you're after.

[rekotc]

thanks again, i was simply trying to solve that damn equation so...another question..should i use a source with a 704x576 resolution or simply keep the 720x576 since my PAL analogic tv already uses the central 704x576?

[aedipuss]

unless you see a black border on the sides of your 720 video, stick with 720.

[intracube]

so...another question..should i use a source with a 704x576 resolution or simply keep the 720x576 since my PAL analogic tv already uses the central 704x576?

I need to know in more detail what you're trying to do. If your source is a 'PAL' DV camcorder, the video will be 720x576. You can convert this to a DVD and keep the resolution at 720x576.

If you're making your own content for a DVD, you can create either 720x576 or 704x576 MPEG files. Although 720x576 is much more commonly used.

Unfortunately there's a complication with producing content for DVD. Although many standard definition video formats (DV, D1, Digibeta, etc) are based on the Rec. 601 standard, there is some confusion around DVD-Video...

Some films on commercial DVDs use the whole 720x576 frame for the image. This doesn't follow the Rec. 601 standard where only a 702x576 region of the frame is used. Other DVDs do follow the 601 standard.

To complicate things further, different outputs on DVD players do things differently. In some cases analogue composite/s-video/RGB outputs assume the image is within the 702x576 area, while HDMI outputs assume the whole 720x576 area is used. This is based on information provided by people on this forum.

Even with these inconsistencies, the video will only be distorted by ~2% at most.

[intracube]

unless you see a black border on the sides of your 720 video, stick with 720.

Even if there are black bars on the sides of the video, it might not be a problem.

rekotc; This thread is relevant:
http://forum.videohelp.com/threads/338952-Getting-perfect-AR-on-wide-TV

also this link:
http://lipas.uwasa.fi/~f76998/video/conversion/#faq

[rekotc]

thanks again for the explanation, i was simply experimenting with different file resolutions and formats. Since i read them through an usb port i dont need to follow the DVD standard, im doing it for the sake of learning