[M4IF Technotes] h.263 motion vector predictor

[Gary Sullivan]

Skipped MBs in P pictures use (0,0) MVs.  Doesn't matter whether short
header or not.
-Gary S.
+> -----Original Message-----
+> From: technotes-admin   lists.m4if.org 
+> [mailto:technotes-admin   lists.m4if.org] On Behalf Of Ariel David
+> Sent: Wednesday, May 21, 2024 8:25 AM
+> To: technotes   lists.m4if.org
+> Subject: RE: [M4IF Technotes] h.263 motion vector predictor
+> 
+> 
+> Maybe the problem is in my median prediction.
+> 
+> are predictors that are skipped macroblock computed 
+> differently or are they considered 0,0 motion vector.
+> For example:
+> if the top left MV is 0,0, the top MV is 1,1 and the left is 
+> skipped will the predictor be 0,0 (regular median) or 1,1 
+> (since the left is not considered).
+> 
+> Ariel
+> 
+> -----Original Message-----
+> From: Herbert Thoma [mailto:tma   iis.fhg.de]
+> Sent: Wednesday, May 21, 2024 5:39 PM
+> To: Ariel David
+> Cc: technotes   lists.m4if.org
+> Subject: Re: [M4IF Technotes] h.263 motion vector predictor
+> 
+> 
+> Ariel David schrieb:
+> > 
+> > Hi,
+> > 
+> > I am trying to decode mpeg-4 video files with short header 
+> (h.263 format).
+> > I've looked though the mpeg-4 standard and found not 
+> mention of a different method for motion vector predictor.
+> > The mpeg-4 method is the median of the 3 adjacent macroblocks.
+> > This does not seem to work in h.263 (mpeg-4 with short headers).
+> 
+> Why not? It's exactly the same in H.263.
+> 
+>  Herbert.
+> 
+> > I assume it's more like mpeg-2, either left or top 
+> macroblock, but I can't find any mention in the standard.
+> > 
+> > Can someone help me out?
+> > 
+> > Thanks,
+> > 
+> > Ariel
+> > 
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+> 
+> -- 
+> Herbert Thoma
+> FhG-IIS A, Studio Department
+> 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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