[M4IF Technotes] Global Motion Compensation

[Prabhudev Hosur]

Global Motion CompensationPatrick,
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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