[Mp4-tech] [H.264] Macroblock Skip at the border of the picture

[Luca]

Dear Experts,
I would like to ask you whether some of you can explain me this
behavior of the JM. When encoding some static sequences, it looks like
that the MB in the first row and in the first column of the picture
are not skipped increasing the mb_skip_run counter but rather encoded
in the following way:
*********** Pic: 1 (I/P) MB: 2 Slice: 0 **********
@1499 mb_skip_run
       1 (  0)
@1500 mb_type (P_SLICE) ( 2, 0) =   1                                  1 (  0)
@1501 mvd_l0 (0) =   0  (org_mv -16 pred_mv -16)                   1 (  0)
@1502 mvd_l0 (1) =   0  (org_mv   0 pred_mv   0)                    1 (  0)
@1503 CBP ( 2, 0) =   0
        1 (  0)
I would like to ask you if this is equivalent to skip the macroblock
and, in this case, why the encoder not decide to directly skip it by
means of mb_skip_run.
Thank you,
Luca.