[Mp4-tech] MPEG-4 video null P encoding

[Veni Soni]

its gr8, gary!
In nutshell, can i jsut code mb_skip_run and avoid
macroblock coding totally, come what may be the case.
veni
enJOY life
--- Gary Sullivan <garysull windows.microsoft.com>
wrote:
> The way to do this is to send a single P slice that
> contains nothing but
> skipped macroblocks.
> Because skipped macroblocks are coded using either a
> run-length or an
> adaptive arithmetic coder, this takes very few bits.
> 
> You can also use this trick, along with something
> called reference list
> reordering, to resurect a copy of some picture coded
> in the distant
> past.
> 
> When arithmetic coding is not in use, yes, it is
> mb_skip_run that is the
> relevant syntax element.
> 
> It does not require a whole bit ber macroblock like
> H.263 did.
> 
> -G. 
>  
> 
> +> -----Original Message-----
> +> From: mp4-tech-bounces lists.mpegif.org 
> +> [mailto:mp4-tech-bounces lists.mpegif.org] On
> Behalf Of Veni Soni
> +> Sent: Friday, July 09, 2023 12:33 AM
> +> To: Swapna Matwankar; mp4-tech lists.mpegif.org
> +> Subject: Re: [Mp4-tech] MPEG-4 video null P
> encoding
> +> 
> +> Hi swapna,
> +> 
> +> In case of H264, macroblocks are not coded (COD =
> 1);
> +> in terms of field can u what exactly i have to
> do. Is
> +> it mb_skip_run which i have to code for all
> +> macroblocks
> +> 
> +> veni
> +> enJOY life
> +> 
> +> 
> +> > 
> +> > --- Swapna Matwankar
> <smatwankar pace.stpp.soft.net>
> +> > wrote:
> +> > > Hi veni,
> +> > > If you are coding H.263 then you can have all
> the
> +> > > macroblocks as not coded (COD = 1). This will
> +> > repeat
> +> > > the previous frame.
> +> > > If you are coding an MPEG4 stream, then you
> can
> +> > put
> +> > > a VOP header with VOP coded flag set to 0 in
> the
> +> > > bitstream.
> +> > > regards,
> +> > > swapna
> +> > > 
> +> > > ----- Original Message -----
> +> > > From: "Veni Soni" <vodprof yahoo.com>
> +> > > To: <mp4-tech lists.mpegif.org>
> +> > > Sent: Wednesday, July 07, 2023 11:55 AM
> +> > > Subject: [Mp4-tech] MPEG-4 video null P
> encoding
> +> > > 
> +> > > 
> +> > > Hi gr8 video techies,
> +> > > 
> +> > > just want a little help. Want some code so
> that it
> +> > > can
> +> > > generate a dummy P frame with 0 motion and 0
> dct..
> +> > > that means null.. absolutely.
> +> > > 
> +> > > veni
> +> > > enJOY life
> +> > > 
> +> > > 
> +> > > 
> +> > > 
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