[M4IF Technotes] Video Object Plane Header

[Nitin Gupta--DSP, Noida]

Hi all,
	I have some doubts regarding the header of the 
video object plane in an Mpeg4 stream. I hope that somebody 
would help me out .
1) In the video object plane header the first parameter
that is encoded is the vop coding type & the parameter
vop_coded ( that tells whether the vop is coded or not )
comes later. I want to know why are these parameters 
encoded in this order since if vop is not coded then we are 
hardly bothered that the vop coding type is I or P.
Shouldn't the vop_coded parameter come before the
vop coding type so that if vop is not coded we need not
decode any further information ?
2) Another parameter that comes in the vop header is
vop_quant. As i can interpret its value can range from
1 to 31. But i would like to know that is the value 0 for
vop_quant illegal ? Because i think we can have the
value of vop_quant in the header to be 0 & then we can 
have the value of d_quant to be +1 or +2 in the first macroblock
of the vop ( provided that the mb_type of the macroblock
is either 1 or 4 ) & that would put the things right.
Thanx & Regards,
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Nitin Gupta
Member Technical Staff, 
MicroProcessor Software Group (MPSG),
A-5, Sector 24,
HCL Technologies, Noida 201301, India
+91 11 91 4534265-66 (O) Extn: 2561
gnitin   noida.hcltech.com
g_nitin007   yahoo.com
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