[Mp4-tech] H.264: about the caculation of mvCLX

[Gary Sullivan]

You are looking at an old version of the standard.  Get a new copy.  You
can get it for free from the ITU by following the directions on the
MPEG-IF web site.
Best Regards,
Gary Sullivan 
+> -----Original Message-----
+> From: mp4-tech-bounces lists.mpegif.org 
+> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Alan Thomson
+> Sent: Tuesday, June 28, 2023 7:30 AM
+> To: AngelZhang innosis.com.cn; mp4-tech lists.mpegif.org
+> Subject: RE: [Mp4-tech] H.264: about the caculation of mvCLX
+> 
+> Hi -
+> 
+> The equations are correct; the text is misleading.
+> Delete "multiplying", insert "dividing" and it makes more sense.
+> For example a luma component of 3 (quarter-luma-samples)
+> yields a chroma component of 3 (eighth-chroma-samples).
+> 
+> BR,
+> Alan
+> 
+> > -----Original Message-----
+> > From: AngelZhang innosis.com.cn [mailto:AngelZhang innosis.com.cn]
+> > Sent: 28 June 2023 02:47
+> > To: mp4-tech lists.mpegif.org
+> > Subject: [Mp4-tech] H.264: about the caculation of mvCLX
+> > 
+> > 
+> > hi experts,
+> >   In the part 8.4.1.4 of H264 standard,the description of mvCLX's
+> > derivation is written as following:
+> >   "if the current macroblock is a frame macroblock,the 
+> horizontal and
+> > vertical components of the chroma motion vector mvCLX are 
+> derived by
+> > multiplying the corresponding components of luma motion 
+> > vector mvLX by 2,
+> > through mapping one-quarter sample mvLX units to one-eighth 
+> > sample mvCLX
+> > units"
+> >   but the formular :
+> >     mvCLX[0]=mvLX[0]
+> >     mvCLX[1]=mvLX[1]
+> >   havn't implement what the standard has said to multiply 2.
+> > 
+> >   i am confused about it very much.please give me your idea.
+> > 
+> > thanks
+> > angel
+> > 
+> > 
+> > 
+> > 
+> > 
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