[Mp4-tech] Simple question for simple profile levels

[Padmavathi]

Hi..
We would like to know some information regarding confirmance streams. We
found some of the compliance streams from the
ftp://ftp.tnt.uni-hannover.de/pub/MPEG/video/conformance/.
We were not able to find bitstreams donated by 'MPEG-4 Platform Verification
Bitstream Development Project of Japan'. These test vectors are mentioned in
the subclause 4.5.8 of ISO/IEC 14496-4:2000(E).
Thanks in advance for rour help.
Regards,
Padmavathi.
----- Original Message -----
From: "Gary Sullivan" <garysull windows.microsoft.com>
To: "Yogender Kumar Gupta, Noida" <ykgupta noida.hcltech.com>; "????"
<k_okamo sic.co.jp>; <mp4-tech lists.mpegif.org>
Sent: Saturday, February 21, 2024 1:44 AM
Subject: RE: [Mp4-tech] Simple question for simple profile levels
>
> I'm not sure that's true.  SP L0 did not exist in the original MPEG-4
> Visual specification.  There is a special (new)
> profile_and_level_indication code (0x08) used to indicate that the
> stream conforms to SP L0.  Decoders are normally designed to check the
> value of profile_and_level_indication, and to reject any stream that
> contains a value of profile_and_level_indication that they do not
> recognize (unless the standard tells them to do otherwise, and I don't
> think this standard does).  Since the code for SP L0 was selected AFTER
> the higher levels of SP were specified, decoders that were designed
> before SP L0 existed will probably reject all SP L0 bitstreams.  At
> least that's my understanding.
>
> SP decoders designed after SP L0 existed would probably accept SP L0
> bitstreams.  I don't personally think they should be required to accept
> them, because this would mean that the addition of SP L0 would be a
> non-compatible amendment to an existing standard (an amendment that
> declares existing conforming implementations to be non-conforming) --
> something that is ordinarily not considered good standardization
> practice.  However, I don't actually see any statement in the standard
> that indicates that support for L0 is not required for decoders that
> support higher levels.
>
> So I think the answer to the question is somewhat in a gray area.
> Before January 2001 I think the answer was more clear.
>
> However the bottom line is that if you're designing a decoder NOW, you
> should definitely support L0 if you're going to support L1.  It requires
> no real extra effort and makes you compatible with more encoders.
>
> Best Regards,
>
> Gary Sullivan
>
> +> -----Original Message-----
> +> From: mp4-tech-bounces lists.mpegif.org
> +> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of
> +> Yogender Kumar Gupta, Noida
> +> Sent: Friday, February 20, 2024 2:36 AM
> +> To: ????; mp4-tech lists.mpegif.org
> +> Subject: RE: [Mp4-tech] Simple question for simple profile levels
> +>
> +>
> +> Hi Kohei,
> +> All decoders which support Simple Visual Profile L1 would
> +> automatically
> +> support L0 and you need not worry about that.
> +> Warm Regards
> +> Yogender
> +>
> +> -----Original Message-----
> +> From: mp4-tech-bounces lists.mpegif.org
> +> [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of
> +> k_okamo sic.co.jp
> +> Sent: Friday, February 20, 2024 5:58 AM
> +> To: mp4-tech lists.mpegif.org
> +> Subject: [Mp4-tech] Simple question for simple profile levels
> +>
> +>
> +> Hello Everyone
> +>
> +> I'm currently in a mobile phone developing project,
> +> and this phone device is expected to work as a media player.
> +> It's about to support MPEG4 , simple visual profile L1.
> +> However I'm wondering whether a "simple visual profile L1 support"
> +> covers the lower level (L0) or not.
> +> Does the simple visual profile levels have lower compatibility?
> +>
> +> Regard,
> +> Kohei Okamoto
> +>
> +>
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