[M4IF Technotes] RE: [M4IF Infolist] Interoperability

[Rob Koenen]

In general, these discussions should take place on the Technotes list.
This is a list for news about MPEG-4.
Having said that, I'd like to note the following.
Rebooting machines is never an issue with the standard, but always with
the local machine and possibly the MPEG-4 implementation running on that
machine.
MPEG-4 has defined very detailed specifications for interoperability, enough
to achieve just that: interoperability. To use MPEG-4 in a specific
environment,
it is useful to augment standards like MPEG-4 with specifications like
ISMA's.
ISMA specifies which conformance points (Profiles and Levels) in the MPEG-
4 standard to use, it is an industrial agreement on using subsets of the
MPEG-4 
standard. It also specifies how to transport the bits, which MPEG-4 does
only 
partially.
In MPEG there has been and stil is very extensive bitstream exchange.
This is complemented by the interoperability testing in M4IF and ISMA and
other fora.
The interop testing in M4IF encompasses exchanging reaw bitstreams and 
compound MP4 files between different companies, the only aim is to achive
full 
interoperability. It is working towards streaming interop tests.
Participants in
M4IF are both MPEG members and non-MPEG members.
Best,
Rob
-----Original Message-----
From: Ram Kordale [mailto:kordale   kasenna.com]
Sent: Thursday, October 04, 2023 12:17 PM
To: Tushar N Padhye; infolist   lists.m4if.org
Subject: Re: [M4IF Infolist] Interoperability
I am new to this list and do not understand m4if well enough. so, please
pardon any ignorance in my response.
i have had similar experiences. mostly, it has been because most products do
not completely specify the codec/profile/level support. Ofcourse, this does
not mean that you would need a reboot of a machine. But, in general, i find
that getting to a very fine granular level of detail in the specifications
is the only way to avoid this problem. 
This is what organizations like the ISMA help achieve. They help nail down
specifications to a much finer level, build conformance tools and
conformance programs. Of course, this is ongoing work and hopefully by the
end of the year, you should have ISMA stamped devices that will definitely
interoperate.
Thanks.
Ram
At 07:11 PM 10/4/2024 +0530, Tushar N Padhye wrote:
Hi 
There might be a fundamental flaw in my logic and I'd appreciate if someone
could correct me. 
I created a .MP4 file using the Dicas encoder. And I try playing it with the
Philips MPEG-4 player.. Guess what I had to reboot my machine.
If the MPEG-4 standard aims at interoperability then I should assume that
any player should play a .MP4 file no matter whose 
MPEG4 encoder I use. 
Can any one share their thoughts on this ? 
Regards, 
Tushar 
-----Original Message----- 
From: Klaus Diepold [ mailto:Klaus.Diepold   dynapel.de
<mailto:Klaus.Diepold   dynapel.de> ] 
Sent: Tuesday, October 02, 2023 8:54 PM 
To: Christophe.Vermeulen   alcatel.be; infolist   lists.m4if.org 
Subject: RE: [M4IF Infolist] Relationship of MPEG-2 and -4 differences 
with quality/bitrates 
Chritophe, 
Dicas GmbH in Berlin is offering a Core Profile encoder SDK, 
which offers non-rectangular video objects (Binary Shape Coding). 
It is in fact pretty fast (I think even real-time), 
as long as you have the shapes of the non-rectangular video objects upfront.
I doubt that MPEG-4 simple visual profile is offering better compression for
TV quality video than MPEG-2 Main Profile Main Level. This is also based on 
the 
fact that simple visual profile is only specified up to CIF resolution and 
to a 
maximum bit rate of 384 kbit/sec, while not supporting (of course) 
interlaced video. 
DivX is almost conformant to simple visual profile (actually it is missing a
bit in the syntax). 
DivX does not obey to the level definitions in the standard, so you can 
actually code video 
with high bit rate and higher resolution. 
Cheers 
Klaus Diepold 
DynaPel Labs 
+-----Original Message----- 
+From: infolist-admin   lists.m4if.org 
+[ mailto:infolist-admin   lists.m4if.org
<mailto:infolist-admin   lists.m4if.org> ]On Behalf Of 
+Christophe.Vermeulen   alcatel.be 
+Sent: Tuesday, October 02, 2023 4:42 PM 
+To: infolist   lists.m4if.org 
+Subject: [M4IF Infolist] Relationship of MPEG-2 and -4 differences with 
+quality/bitrates 
+ 
+ 
+Hi All, 
+ 
+Maybe this is a FAQ, but is there a list or reference 
+on the differences between MPEG-2 and MPEG-4 that 
+really tries to explain why MPEG-4 actually provides 
+better compression for TV-like quality ? 
+ 
+I looked at the MPEG.org site, but the page from 
+Roberto Grandi seems to have disappeared and can't 
+be found even by Google, and the "Structure of MPEG-4 
+Video Coding" at HHI Berlin lacks many pictures (I get 
+some text in German) and doesn't explain which of all 
+those techniques are used in current codecs such as DivX, 
+or in the simple visual profile. 
+ 
+Is there any real-time codec up there that can handle 
+non-rectangular VOPs ? 
+ 
+Thanks for your help. 
+ 
+Christophe. 
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+ 
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