[Mp4-tech] [video]Padding in non standard videos

[Gururaj Bhat]

Thanks Herbert for your answer.
did that file play on your decoder or any verification model without any
pink spots?
Please let me know.
Regards,
Gururaj Bhat
On 2/21/07, Herbert Thoma <herbert.thoma iis.fraunhofer.de> wrote:
>
> Hi,
>
> I believe that the file is correct.
>
> The encoder can put what it likes into the not displayed
> rows (140 - 143). The decoder has to use these decoded
> pixel values in case of UMV.
>
> See subclause 7.6.4 of ISO/IEC 14496-2:2004:
> "Note that for rectangular VOP, a reference VOP is defined by
> video_object_layer_width and video_object_layer_height, extended
> to a multiple of 16."
>
> We had a discussion about this padding issue on this reflector
> at the end of November 2006.
>
> Kind regards,
> Herbert.
>
> Gururaj Bhat schrieb:
> > Hi all,
> >
> > I have attached a file of size 176 x 140 (pigs.3gp) which when played on
> my
> > decoder,is showing pink patches at the bottom.
> > I feel that this is a non standard file in which the encoder has not
> padded
> > the remaining 4 columns with the last pel data ( ie with column 140) but
> > with some random data which in this case happens to be pink.
> > I guess that when the decoder has UMV ( unlimited motion vector's) which
> > point outside the frame size 176 x 140 it picks up this random data and
> > that's the reason for the pink patches to be seen.
> > Some other decoders also play this file similarly but decoders like
> > quicktime , real player etc play the file without any pink patches.
> > Could you please check how this file plays with your decoders ?
> > I would be interested in knowing how the MPEG VM ( verification models)
> > play
> > out this file .
> >
> > You can refer to subclause 7.6.1 of the MPEG-4 standard which explains
> > about
> > the padding process for non-standard sizes.
> >
> > Thanks
> >
> >
> >
> > On 2/15/07, pankaj bajpai <pankaj_bajpai_iet operamail.com> wrote:
> >>
> >> Dear Gururaj,
> >>
> >> In the sequence header, it is the original size ie non-padded size
> >> that need to be put.
> >>
> >> with regards
> >>
> >> > ----- Original Message -----
> >> > From: "Gururaj Bhat" <bs.guru gmail.com>
> >> > To: "pankaj bajpai" <pankaj_bajpai_iet operamail.com>
> >> > Subject: Re: [Mp4-tech] [video]Padding in non standard videos
> >> > Date: Wed, 14 Feb 2024 11:21:39 +0530
> >> >
> >> >
> >> > Hi Pankaj,
> >> >
> >> > Thanks for your answer.
> >> > I have one more doubt.Suppose it is padded,then what is the frame
> size
> >> that
> >> > has to be incorporated in the header of the encoded file?is it the
> >> original
> >> > size or the padded size?
> >> >
> >> > Suppose the padded size is included,then is there any way for the
> >> decoder to
> >> > know that the video is padded,and how much?
> >> >
> >> > Thanks in advance.
> >> >
> >> >
> >> >
> >> >
> >> > On 2/14/07, pankaj bajpai <pankaj_bajpai_iet operamail.com> wrote:
> >> > >
> >> > > Dear Gururaj ,
> >> > >
> >> > > Yes encoder need to take care of padding. This is because the DCT
> is
> >> > > performed on the 8x8 blocks. SO for border MBs, if you dont do
> >> padding,
> >> > > there will not be sufficient elements to perform DCT.
> >> > >
> >> > > With regards
> >> > >
> >> > >
> >> > > > From: Gururaj Bhat <bs.guru gmail.com>
> >> > > > To: mp4-tech lists.mpegif.org
> >> > > > Subject: [Mp4-tech] [video]Padding in non standard videos
> >> > > > Date: Tue, 13 Feb 2024 16:17:03 +0530
> >> > > >
> >> > > >
> >> > > > Hi all,
> >> > > >
> >> > > > I have a case in which the encoded mpeg4 video is of size
> 176*140.
> >> > > > Since the macroblock size is 16*16,140/16 is not an integer.
> >> > > > So,does encoder need to take care to pad the video frame while
> >> encoding?
> >> > > > or is it the duty of the decoder?
> >> > > >
> >> > > > regards,
> >> > > > Gururaj Bhat
> >> > > >
> >> > >
> >> > >
> >> > >
> >> > > Pankaj Kumar Bajpai
> >> > > Mulitimedia Engineer
> >> > > India
> >> > >
> >> > >
> >> > > --
> >> > > _______________________________________________
> >> > > Search for products and services at:
> >> > > http://search.mail.com
> >> > >
> >> > > Powered by Outblaze
> >> > >
> >>
> >> >
> >>
> >>
> >>
> >> Pankaj Kumar Bajpai
> >> Mulitimedia Engineer
> >> India
> >>
> >>
> >> --
> >> _______________________________________________
> >> Search for products and services at:
> >> http://search.mail.com
> >>
> >> Powered by Outblaze
> >>
> >
> >
> > ------------------------------------------------------------------------
> >
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>
> --
> Herbert Thoma
> Head of Video Group
> Multimedia Realtime Systems Department
> Fraunhofer IIS
> Am Wolfsmantel 33, 91058 Erlangen, Germany
> Phone: +49-9131-776-323
> Fax:   +49-9131-776-399
> email: tma iis.fhg.de
> www: http://www.iis.fhg.de/
>
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