Hey Wilbert. It is not, that I don't know about this sampling stuff
(After I learned a lot while being in this forums
)
but it seems, that reality and theory differ (like the 1.066 and 1.094 PAR for the PAL-Stuff)
after examining some videos (two different cams),
I think that the chroma is sampled like conventional YV12.
Knows the devil why.
If you own an DV-Cam (I do not. I am only the person, who processes the videos...)
You may print out an image containing pure blue background with pure red diagonal objects on it (lines, blocks or circles). then you make a short still standing video of this (well lightened) picture.
This would be IMO the only possibility to check, whether the Cameras follow the standard or not.
Natural video is not that suited for checking for half pel chroma displacements, I think.
So I came to that (probably wrong) conclusion that DV Cams are building conventional YV12.
I also want to mention, that the canopus DV-Codec samples a RGB-Input with standard YV12.
Also its point-upsampling is in the grid of standard YV12.
Which (the point upsampling) is NOT a bad thing, after doing some tests!
Most MPEG-2 Encoders need RGB (TMPGenc) or YUY2 (CCE etc..) input, which gets downsampled to YV12 again by averaging nearby pixels (not 100% correct, I know...).
With IDENTICAL nearby pixels like it is the case with point-upsamples DV, the chroma won't bleed.
but if the DV-decoder would to a proper visual (with averaging) upsampling to YUY2 and the encoder the downsampling to YUY2 the chroma is bleeded like hell....
reinterpolate420() is only needed, if heaviy image manipulation (destroying pixel structure) is wished (deshaking, resizing...)
for linear editing it is completely obsolete, IMO.
when I need to deinterlace the stuff, I am currently not 100% sure, whether I shall use
reducetoyv12().YV12deinterlacer()
(gives lowest chroma manipulation as possible!)
or
reinterpolate420().YUY2deinterlacer()
(chroma-artifacts of the deinterlacer are not that visible, chrom is slightly bleeded)
Wilbert, what do you think?