[Mp4-tech] calculating chroma MVs??

[Parag Chaurasia]

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  Hi Harish,
    The Motion Vector (MV) for each macroblock (either 1 MV or 4MVs) in a VOP is EXTRACTED from the MPEG-4 bitstream. This (These) motion vector(s) are used for Motion Compensation of the Luminance Component of that macroblock. 
  Chroma component Motion Vector is DERIVED from the Luma Motion Vector(s) and thereafter Motion Compensation of Chroma components is performed. 
  See Sections 7.6.3 and 7.6.5 for more details.
  Best Regards,
  Parag. 
On Wed, 31 Dec 2023 harish.vasudeva amd.com wrote :
>Hi,
>
>  From looking at the MPEG4 reference software, it seems that first MotionComp is performed on the 4 luma blocks. The output from this is used to get the MotionVectors for the chroma pair! Is that correct? If so, is that a MPEG-4 requirement?
>
>  Any info on that is greatly appreciated.
>
>Best Regards,
>HARISH V
>
>
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