[M4IF Technotes] Questions of GMC and Interlace in MPEG4

[liuxiaolei vip.sina.com]

 Dear MPEG4 Experts,
   I receive your mail of Warping and Warping Vector in Sprite decoding,very thanks!
   In the MPEG-4 spec. (ISO 14496-2), GMC(global motion compensation) decoding is in Section 7.8.7.
   We know the candidate predictor is obtained as the averaged value of the pel-wise motion vectors in the block when mcsel == ¡®1¡¯in GMC decoding. 
   Averaged value of pel-wise vectors is calculated using 
the all luminance pixels in the macroblock.    
   In Interlaced interlaced intra blocks,We know the positions of top field blocks and buttom field blocks.
Now my questions is:
        How obtained the per luminance pixel motion vectors?
        How show of top field blocks and buttom field blocks in display when decoding over, one by one show or  first show all the top field blocks afterward show all the buttom field blocks?     
   Thanks!
   Xiaolei Liu
______________________________________
===================================================================