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

[Christoph Lampert]

On Mon, 28 Oct 2023 cloverleafland   mail.hongkong.com wrote:
> Dear Mithun Nayak, 
> 
> Thanks for that... but I am still confused about the need of motion vector of chroma blocks... 
> If we only need to perform motion estimation on Y blocks, then why do we
> still need to store the motion vectors for U & V blocks?

We don't.  Either one 1 motion vector is saved (INTER) which describes the
motion of whole 16x16 lumi block and it is used for both 8x8 chroma
blocks, too. 
Or 4 motion vectors are saved (INTER4V) which describe motion of the 4
8x8 block in lumi and chroma vectors are calculated from those 4. 
No vectors is of course possible, too, and B-frames are also different,
but this is the "ordinary" case.  
Christoph Lampert
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