[Mp4-tech] reference of intra and inter Macroblcok!

[AngelZhang innosis.com.cn]

hi,experts
who can tell me concrete reference rule of intra macroblcok and inter
macroblock? questions as following:
1)Macroblocks' prediction in I frame can only take macroblock in the same
slice as reference, then when one frame has two slices, then does
macroblock in one slice can take the macroblock in another slice of the
same frame as reference?
2)P frame can have intra macroblock and inter macroblock. as far as inter
macroblock is concerned,does it only take macroblocks in other frames
decoded before as reference? or other rule? and what about reference of
intra macroblocks in the P frame?
I am confused very much, please give me some suggestions!
thanks in advance
BR
angel