[M4IF Technotes] Global Motion Compensation

[Rob Koenen]

Just to clarify:
The only reason there is no sprite in ACE is that we decided
not to have it ... it has nothing to do with it being a Version 1 tool.
There are many V.1 tools in profiles that were only defined in V.2
Thanks,
Rob
-----Original Message-----
From: Prabhudev Hosur [mailto:Prabhudev_Hosur   objectvideo.com]
Sent: Monday, October 29, 2023 2:09 PM
To: 'Patrick Ng'; 'MPEG4 technical notes (E-mail)'
Subject: RE: [M4IF Technotes] Global Motion Compensation
Patrick,
For Advanced Coding Efficiency,  there is 'X' mark in front of Global motion
compensation tool in V2-39.  Whereas, there is no 'X' mark in front of
'Sprite', because (in my opinion) in V2-39, 'Sprite' implicitly means
'static sprite', which is a Version-1 Tool.   
Thus, Advanced Coding Efficiency profile supports GMC, but not static
sprites.
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 4:33 PM
To: 'MPEG4 technical notes (E-mail)'
Subject: RE: [M4IF Technotes] Global Motion Compensation
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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