[M4IF Technotes] Re: Need advice on Motion Estimation, please advise....

[Mithun N]

Hi ...
Motion estimation need not necessarily be done on
16 * 16 blocks.
Infact if the search is performed on 4blocks of
8*8 then it is called 4MV searching.
But that would consume a lot of time..searching
for 4 blocks independently.
Also ...motion estimation isnt carried out for
chroma blocks..but the decoder assumes that
the value of motion vector shall be
1) half that of luma vector (if search is for
16*16 block)
2) sum of non transparent luma vectors % num of
non transparent luma blocks in a mcroblock (for 4
MV)
The  chrominance Motion vectors have to be rounded
appropriately as suggested in ISO 14496-2..
regards
Mithun Nayak
-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf
Of
cloverleafland   mail.hongkong.com
Sent: Monday, October 28, 2023 4:02 PM
To: technotes   lists.m4if.org
Subject: [M4IF Technotes] Re: Need advice on
Motion Estimation, please
advise....
Dear all,
I am currently working on a project to build a
MPEG-4 encoder. I got confusion on the process of
motion estimation. would anyone help explaining
why the motion estimation is done on 16x16 block
based but not in 8x8 block based?
Also, for a macroblock, it consists of 4 8x8 Y
blocks and 1 8x8 U block and 1 8x8 V block, would
anyone advise whetehr the motion estimation on Y,
U and V are done seperately or not?
Thanks so much....
Regards,
Clover
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