For B field pictures, the spec says, > The prediction shall be made from the field of the same parity as the field being predicted. I did it. Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> (cherry picked from commit 8b154cb3e90a3e599cadf477d815a9854b7bb4e1) Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>