[FFmpeg-devel] Help: Get motion vector value from previous and next frame FFMPEG

[Boris]

Apologize me if this mailing list is not for such questions.
 I want help, then I think that here is the best place.
Can you tells me how can I do to get motion vectors values (mvx, mvy) from
previous and next Frame during transcoding with MPegEncContext structure,
please?
For current Frame, s->p_mv_table gives me this values. But I don't know how
can I do
for next and previous frame in encoding order.

Regards