Extracting top & bottom fields from a YUV 4:2:0 Frame I am wondering what would be the right approach to extract top and bottom fields from a YUV 4:2:0 frame.

In the YUV 4:2:0 representation, Luma and Chroma samples are located as shown below:

Y Y Y Y Y Y Y Y
c&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c&nbsp;&nbsp;&nbsp;&nbsp;c
Y Y Y Y Y Y Y Y

Y Y Y Y Y Y Y Y
c&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c&nbsp;&nbsp;&nbsp;&nbsp;c
Y Y Y Y Y Y Y Y

Hence, one needs to be careful while extracting chroma top and bottom fields (due to the chroma offset problem). I have tried a few methods (using asymmetric filters and such), but none have been satisfactory.  

Are there some good resources (papers) on this problem?
Assuming the encoder properly low-pass filtered the chroma before sampling (which may not always be true), chroma samples from the adjacent macroblocks might need to be used to properly reconstruct (interpolate) any per pixel color.  Those samples may exist due to motion compensation from previous fields, or might need to be inferred by reflecting, duplicating or extrapolating edge data.