[M4IF Technotes] Q: reduced res VOPs

[Gary Sullivan]

Aman et al,
1. Reduced Resolution VOPs (RRV's) are not in Simple Profile.
   In fact they are a version 2 feature, so they could not
   be in the Simple Profile (which is a version 1 feature).
2. I believe the answer to whether they have something to
   do with Dynamic Resolution Conversion (DRC) or not depends
   on your definition of what DRC is.  My best answer is Yes,
   since table V2-39 and table G-2 refer to DRC as a tool
   that's in MPEG-4 visual, although the term is not defined
   anywhere in the standard and in fact doesn't even appear
   anywhere else in it.  This "phantom tool" is included in
   the Advanced Real-Time Simple profile only.  I can't think
   of anything else that DRC might mean, so it must mean RRV.
   This is clearly a bug in the spec.  I will bring it to
   MPEG's attention.
RRV's involve sending changes from the reference picture at a
lower resolution than that of the reference picture while retaining
higher resolution in the decoded picture than what is used for the
updates.  They are primarily useful for temporary situations of
codec stress when rapid motion appears in front of a detailed
static background.  They do not involve dynamically converting the
resolution of the reference picture or the current decoded picture
to a different size, as one might think from the term "resolution
conversion".  In H.263 terminology, RRV's resemble Annex Q (reduced
resolution update) rather than Annex P (reference picture resampling).
The term RRV really seems more appropriate than the term DRC -- which
is probably why the term RRV is used many times while the term DRC
appears only in two forgotten places.  Unfortunately those two
forgotten places are crucial ones, as they are where the profiles
are defined.
Best Regards,
Gary Sullivan
+> -----Original Message-----
+> From: asjabbi [mailto:asjabbi   micron.com] 
+> Sent: Tuesday, April 02, 2024 12:22 PM
+> To: technotes   lists.m4if.org
+> Subject: [M4IF Technotes] Q: reduced res VOPs
+> 
+> 
+> 
+> Quick question:
+> 
+> Are reduced resolution VOPs part of Simple Profile, and are 
+> they in any 
+> way related to the Dynamic Resolution Conversion? 
+> Thanks.
+> 
+> - Aman
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