[M4IF Technotes] object based coding, profiles and bandwidth limitation

[Rob Koenen]

Sheldon,
shape coding is not supported in Simple because Simple is
kept just that way - simple. It was not deemed necessary and 
Simple is the lowest complexity Profile in MPEG-4 Visual.
Low bitrate apps usually require low complexity as well.
The jury is still out on whether object-based coding helps
compression efficiency, but for those who want to try and
prove, there is Core to play with. A few companies actually
implemented this, but not all are around anymore. It may 
come back, who knows. I have seen promising results.
As for bandwidth limitations: of course there are. Otherwise
you'd not be able to implement a decoder and know it would
execute in real time.
See "Information on MPEG-4 Object Types, Profiles and Levels"
on this page: http://www.m4if.org/resources.php
<http://www.m4if.org/resources.php> 
Rob
-----Original Message-----
From: X.D.Cai   sussex.ac.uk [mailto:X.D.Cai   sussex.ac.uk] 
Sent: Tuesday, September 24, 2023 4:35
To: technotes   lists.m4if.org
Subject: [M4IF Technotes] object based coding, profiles and bandwidth
limitation
Dear all :
It is well known that mpeg-4 is object-based coding which supports arbitrary
shape coding in its core profile. Does anybody can tell me why it is not
supported in simple profile?
I believe in many cases, the arbitrary shape object based coding can provide
a better compression rate than rectangle shape or frame coding so that it
can serve low bandwidth applications (in simple profile). 
So is it possible to use arbitrary shape coding technique (by video
segmentation) for simple profile ? Also , are there anyone can tell me if
there are bandwidth limitation designed in the standard for different
profiles ? if so , why ?
Many thanks . 
sheldon 
University of Sussex 
UK
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