[PD] video analysis
chris clepper
cclepper at artic.edu
Tue Mar 25 20:13:58 CET 2003
>Ok, according to that I had it right. if Y is 240*320, then U is 120*160
>and V is 120*160. There's no 60*160 involved...
if both U and V are 1/2 the samples of Y then the format is 4:2:2.
4:2:0 looks like*:
row1 : YYUYYU
row1 : YYVYYV
row3 : YYUYYU
row4 : YYVYYV
for every 4 Y samples there are two samples of U or V and they
alternate every row. the 0 means that the U and V are both
vertically and horizontally subsampled unlike 4:2:2 (YUYV) or 4:1:1
(YYUYYV), which are only horizontally subsampled. so effectively
there are only 1/2 the vertical samples of U and V in 4:2:0. how
those are reconciled into 4:2:2 is left to the decoding/decompression
method. UV data can be either copied or averaged or some sort of
interpolation can take place....
>... unless you have interlacing as well (which I assume is *not* the case.
>I know incoming video is, but isn't that deinterlaced before the input
>card gives a frame ?)
if the incoming video is interlaced then the interlacing might always
be a factor. depending on the computer format you are using for
storage the fields could be kept intact rather than deinterlaced
progressive images, a raw DV stream for example keeps the fields.
*the page Marc Lavallée linked to http://www.fourcc.org/fccyuv.htm
lists the 4:2:0 formats as planar but that might not be the way 4:2:0
is actually stored in DV. anyone know for certain if DV stores
packed or planar data? i'm fairly certain that it's packed. another
link: http://www.dvcentral.org/DV-Beta.html
cgc
More information about the Pd-list
mailing list