[M4IF Technotes] Global Motion Compensation

[Patrick Ng]

Hi Prabhu,
Thanks for the reply.
That is where the confusion comes from.  In Table V2-39, there is no check
mark 'X' in Sprite tool for Advanced Coding Efficiency.  So shouldn't global
motion compensation be not required, should it?
Patrick Ng
-----Original Message-----
From: Prabhudev Hosur [mailto:Prabhudev_Hosur   objectvideo.com]
Sent: Monday, October 29, 2023 2:52 PM
To: 'Patrick Ng'; 'MPEG4 technical notes (E-mail)'
Subject: RE: [M4IF Technotes] Global Motion Compensation
Patrick,
Please note that Sprite is not a video object.  Instead, Sprite is a
VOP_coding_type (or a Tool).
Sprite can be static or GMC.  If the sprite is of type GMC (i.e., S(GMC) ),
then global motion compensation is required.
Advanced Coding Efficiency can support S(GMC), therefore it needs to include
global motion compensation.
Prabhu
-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf Of Patrick Ng
Sent: Monday, October 29, 2023 12:19 PM
To: MPEG4 technical notes (E-mail)
Subject: [M4IF Technotes] Global Motion Compensation
Dear MPEG4 Experts, 
Is Global Motion Compensation (GMC) a visual tool applied to Sprite video
object only?  If the answer is "yes", why in Table V2-39 the Advanced Coding
Efficiency Profile needs to support Global Motion Compensation while it does
not have to support Sprite object?
In the MPEG-4 spec. (ISO 14496-2), GMC decoding is in Section 7.8.7 which is
under the section of 7.8 (Sprite decoding).  That leds me to think that
Global Motion Compensation is for Sprite video object only.
Thanks 
Patrick Ng 
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