[M4IF Technotes] h.263 motion vector predictor

[Ariel David]

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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