[M4IF Technotes] MPEG-4 4MV/interlaced question

[Prabhudev Hosur]

Larry,
That particular sentence in the standard although is not very specific, but
it is not wrong.  Usually it is better to look at the syntax for such
specific things.
PS: Standard defines “progressive” and “interlace” terms
-Prabhu
-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf Of Larry Pearlstein
Sent: Wednesday, October 17, 2023 4:12 PM
To: 'Prabhudev Hosur'; 'M4IF TechNotes'
Subject: RE: [M4IF Technotes] MPEG-4 4MV/interlaced question
Prabhu,
Thank you for your response.
But I'm still wondering how to interpret the line from 7.6.2 that I quoted.
One possible interpretation is that this refers to the fact that progressive
VOPs can use reduced resolution decoding, where the block size is 16 x 16.
But I had assumed that the quote was referring to M & N mentioned in
7.6.2.2.
Perhaps the quoted line should read:
"The sample interpolation for the case of non-integer motion vectors
PRODUCES 16x16 or 8x8 frame blocks WHEN
INTERLACED = 0 OR FIELD_PREDICTION != 1 and PRODUCES 16x8 field blocks when
INTERLACED = 1 AND FIELD_PREDICTION =1."
 instead of:
"The sample interpolation in case of non-integer motion vectors is performed
for 16x16 or 8x8 frame blocks in case
of progressive and for 16x8 field blocks in case of interlaced macroblocks."
It seems that 7.6.2 assumes the definition of "progressive macroblock" and
"interlaced macroblock".  Is there such a definition in the standard?
                Best wishes,
                Larry
-----Original Message-----
From: Prabhudev Hosur [mailto:Prabhudev_Hosur   objectvideo.com]
Sent: Wednesday, October 17, 2023 3:44 PM
To: 'Larry Pearlstein'; 'M4IF TechNotes'
Subject: RE: [M4IF Technotes] MPEG-4 4MV/interlaced question
Larry,
4MV is “not” prohibited for VOL with interlaced =1
-Prabhu
-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf Of Larry Pearlstein
Sent: Wednesday, October 17, 2023 2:15 PM
To: 'M4IF TechNotes'
Subject: [M4IF Technotes] MPEG-4 4MV/interlaced question
Dear M4IF participants,
In the MPEG-4 spec, it says:
"The sample interpolation in case of non-integer motion vectors is performed
for 16x16 or 8x8 frame blocks in case
of progressive and for 16x8 field blocks in case of interlaced macroblocks."
But the syntax doesn't seem to preclude 4MV when doing interlaced VOLs.
Presumably the syntax supports 4MV in interlaced if field_prediction = 0.
Is 4MV prohibited for VOLs where interlaced = 1?
Thank you for your help.
                                Best wishes,
                                Larry
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/mp4-tech/attachments/20011017/cc402123/attachment.html