[Mp4-tech] RE: some questions about H.264 standard!

[LiyongZhou]

The best study materials are the old H26l and JVT standard documents
when those tools were first proposed and later improved during those
meetings. I would hope Gary and others could write/edit a book on how
things developed on each coding tool. Until then, you have to dig
through those materials yourself. Fortunately, they are easier to read
than those of the newest Standard.
Regards,
leon
> -----Original Message-----
> From: mp4-tech-bounces lists.mpegif.org
> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Gary Sullivan
> Sent: 2005年7月1日 10:56
> To: JelyZhu innosis.com.cn
> Cc: mp4-tech lists.mpegif.org
> Subject: [Mp4-tech] RE: some questions about H.264 standard!
>
>
>
> Reply interspersed.
>
> Best Regards,
>
> Gary Sullivan
>
> +> -----Original Message-----
> +> From: JelyZhu innosis.com.cn [mailto:JelyZhu innosis.com.cn]
> +> Sent: Friday, July 01, 2023 3:04 AM
> +> To: Gary Sullivan
> +> Cc: mp4-tech lists.mpegif.org
> +> Subject: RE: some questions about H.264 standard!
> +>
> +>
> +> Hi Gary,
> +>
> +> I think I have understood what you explained for me. Thank
> +> you very much.
> +>
> +> I have another questions now.
> +>
> +> 1. I cannot understand the conception of HRD, SEI and VUI. I
> +> think they
> +> have less relationship with the decoding process. Maybe
> they are some
> +> functions for testing the decoder. Am I right?
>
>
> Not exactly.  The HRD has two purposes: 1) testing whether a bitstream
> produced by an encoder is conforming or not, and 2) testing
> whether the
> video output produced by a decoder is conforming or not.
>
> I advise you to keep studying them.
>
>
> +>
> +> 2. Why do the border of intra macroblock need bigger value
> +> of BS. Would the
> +> intra mode make more serious block effect? From the standard
> +> I cannot get
> +> the reason of choosing different BS value according to
> +> different case.
> +> Could you mind interpret it for me?
>
>
> I think the idea was that if we observe the behaviour of the intra
> coding technology when operating on smooth pictures, we can note some
> extra blocking phenomena.  The design of a deblocking filter
> involves a
> number of perceptual-based considerations.
>
> Perhaps the most important reason to do this is that the spec says you
> must :-).  Whatever the reasons were that we chose to say something in
> the standard, the most important thing once the standard is written is
> to get everyone to follow it properly -- questions about why
> things are
> done the way they are done become somewhat academic.
>
>
> +>
> +> 3. How do I get I_PCM macroblock? This case is so rare that
> +> I cannot test
> +> the function of it.
>
>
> You will get them whenever the encoder will choose to send them.  I
> believe some of the conformance test bitstreams include I_PCM
> macroblocks.  You may also be able to hack the reference
> encoder to make
> it use them more often and then decode the video with your decoder in
> order to test that functionality.
>
> +>
> +>
> +> Best Regards,
> +> Jely
> +>
> +>
> +>
>
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