[Mp4-tech] Mpeg4 Visual Conformance standard Query

[Mohit Agarwal]

Thanks
As far as your doubt the standard says it could be both +/- 1(4.4) and 2 
(4.5.1).Some contradiction is there.
I wanted to apply this +/-1 or 2 pixel difference in case samples with 
IDCT do we have to
open the *yuv* file and scan it then compare each  y  ,u  and v samples  
with  that  generated
by reference decoder .Do we apply same method for  samples  without IDCT.
Please let me know is this the method  or something else.
Best Regards
Mohit
Soumen Kumar Dey wrote:
>It can be possible depending upon the IDct implementation.
>But I've one more doubt. If (+/-1) pixel difference in
>I VOP is possible then it can be (+/- 1, +/- 2 for P VOP)
>because some macroblocks can be predicted from those
>macroblock where pixel difference is (+/- 1). Even it can affect the
>complete sequence.
>If I'm wrong then please clarify me.
>
>Thanks in advacnce,
>Soumen
>
>
>----- Original Message -----
>From: "Mohit Agarwal" <magarwal neomagic.com>
>To: <mp4-tech lists.mpegif.org>
>Sent: Wednesday, April 06, 2024 3:34 PM
>Subject: [Mp4-tech] Mpeg4 Visual Conformance standard Query
>
>
>  
>
>>Hi,
>>The Conformance  standard for Mpeg4 Visual section 4.4 of ISO 14496-4
>>states that
>>compliant decoder shall reconstruct I ,P B VOPs within +/-1 pixel
>>diference compared
>>with that by the reference decoder.How does one measure this +/- 1 pixel
>>difference
>>.After IDCT(before IDCT) we get a set of matrixes ,so this computation
>>is done on
>>that matrix or there is some other way to do it.
>>
>>If anybody could clear my doubts I would be greatful..
>>
>>Regards
>>Mohit
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