[MPlayer-users] seeking explanation of -1 and -2 in -vop scale

[Chris Phillips]

> > a 720x576 vob, 16:9 aspect, cropped with 710:434:4:74, and then to be 
> > scaled with w=640 and y to well.... be right!
> Do not crop to w=710. Try to find a multiple of 16, or, at least, 8.
> Crop systematically to 704 as the rest is black (in Europe, don't know
> in USA). But, anyway, as I have said before: IF IN DOUBT ------> 
> -vop rectangle=your values for crop
> and look at the film!!

so mplayer is giving bad values from cropdetect? that example is what -vop 
cropdetect gave me. And obviously i'm looking at the film, it just kind of 
makes sense to me that mplayers output should conform to something it can 
use...

> and, please, finish this -1, -2 story. Someone has already indicated
> where you can find the explanation...  

erm... sorry if life is too much trouble for you... I know that someone 
said where to find info, and i quoted that reply... i was after an 
explanation of the doc i was pointed to, as it seems aimed at developers 
that already know what the various parameters mean. 

SO, can someone else actually explain briefly what d_width, prescaled 
width and such like actually, using the example in my last mail if it's 
any use:

>-vop scale[=w:h[:c[:p]]]
>    Software scaling (zoom) _and_ yuv<->rgb colorspace conversion
>    w,h (new width/height after scaling) defaults to original width,height
>        note: if -zoom is used, and underlaying filters (including libvo)
>        uncapable of scaling, then it defaults to d_width/d_height !
>        note 2: w/h values -1 means original width/height, 0 means scaled
>        d_width/d_height. -2/-3 means calculating w or h using the other
>        dimension and the original (-3) or prescaled (-2) aspect ratio.
>
>OK, so can someone actually say what d_length, prescaled and the other 
>variables actaully mean? giving an example...
>
>a 720x576 vob, 16:9 aspect, cropped with 710:434:4:74, and then to be 
>scaled with w=640 and y to well.... be right!
>
> 0 = d_height = ?
>-1 = orginal height = 576
>-2 = with aspect = 276? thus making film right shape
>-3 = prescaled = ? aspect of 720x576?

thanks

chris
xxxx