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

[Herbert Thoma]

Gururaj Bhat schrieb:
> Thanks Herbert for your answer.
> 
> did that file play on your decoder or any verification model without any
> pink spots?
> Please let me know.

It did play without pink spots on my decoder. I did not test with
the verification models.
 Herbert.
> 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
>> >> > >
>> >> > >
>> >> > > --
>> >> > > _______________________________________________
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>> >> > >
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>> >> > >
>> >>
>> >> >
>> >>
>> >>
>> >>
>> >> Pankaj Kumar Bajpai
>> >> Mulitimedia Engineer
>> >> India
>> >>
>> >>
>> >> --
>> >> _______________________________________________
>> >> Search for products and services at:
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>> >>
>> >
>> >
>> >
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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/
>>
> 

-- 
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/