[MPlayer-users] question concerning DAR and PAR

belcampo belcampo at zonnet.nl
Wed Nov 25 11:41:28 CET 2009


Steven Miller wrote:
> I have a dvd (ntsc 740x480) that crops to 704x480 (704:480:8:0) which
> changes the DAR from 1.78:1 to 1.74:1. The resulting resolution (on
> playback) ends up being 836x480. Before anyone asks, I have been reading,
> but it's lot to absorb! If I understand correctly, 836x480 maintains the
> 1.74:1 ratio?  Another question is, 1.74 indicates a non square pixel,
> doesn't your typical monitor use square pixels? I'm confused as to what's
> happening here.
> 
> If I wanted square pixels, would using the 'dsize' filter with a resolution
> that is divisible by 16 (scale=-1:-10,dsize=704:400 (this ends up with a
> resolution of 704x400 and a 1.76:1 ratio)) give me square pixels, while
> maintaining a mathematically and visually correct encode?
dsize=704:400 will do this.
Almost all video-sources were/are meant to play on TV, where AFAIK NEVER 
square pixels are used, as in your DVD-example. Square pixels will 
result in more pixels without ANY benefit.
Only if you need to play on devices that don't accept, iPod and others, 
non-square pixels it's usefull/necessary to use square-pixels.
> 
>  
> 
> Thanks in advance!
> 
>  
> 
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