>       Idle question time ;) 
> 
>       y4mscaler can convert from 4:2:2 to other chroma sampling (such as
>       4:2:0).   It seems though that there's more than one flavor of 422
>       out there - there's YUY2, UYVY (at least).   Which one should be fed
>       into y4mscaler?

None of them --- those are all packed formats, and the permutations of
 letters describe different packings, not different subsamplings.

As I have kvetched before, FourCC's are so lacking in meaning as to be
 practically irrelevant.  fourcc.org only lists one code which possibly
 denotes a planar 4:2:2 mode, with the dubious description:

    Y42B - Weitek format listed as "YUV 4:2:2 planar".
           I have no other information on this format.

 Yep, "FourCC - Information you can rely on!"  I'm better off watching
 a Fox News broadcast.

Getting back to y4mscaler, no matter what the subscaling is, the input
 is planar Y'CbCr, with the planes presented in that order.  The 4:2:2
 subsampling is 'industry standard', with the chroma grids vertically
 aligned on the first luma pixel.

>       Hmmm, the next question would be how complete the support is for
>       422 in mpeg2enc but that can wait for another night <grin>

Do any consumer hardware MPEG players support 4:2:2 profiles?  I know
 they exist in the standard, but from what I remember reading, they
 seemed to be discussed as whizzy super-extended modes --- so I'm not
 sure where you would play them even if mpeg2enc would compress them
 for you.

-matt m.


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