[x264-devel] out-of-range motion vectors

[CAdevel]

>
> What part makes sense?
>
> If you're wondering why 37 > mvrange, that might be because mvrange isn't
> strictly enforced. I do strictly enforce the limits of the standard
> (2048 horizontal, 512 vertical), but any smaller mvrange is regarded only
> as a suggestion, and various mv refinement procedures may extend several
> pixels beyond the nominal range.



This part made sense allready. What I did not expect was legal motion
vectors of ranges up to 500. But you explained how this 'drifting' can
happen, and now I understand. Thank you Loren!

By the way, I checked the standard on the limits on the motion vectors and I
found that the horizontal motion vector range is limited to [-2048,2047,75]
luma samples. However the vertical motion vector limit depends on the level
(Table A.1 of the standard) and can be 64, 128, 256, or 512. I assume x264
obeys these limits?

The remarks of Peter makes sense to me. When analyzing movies and finding
these large motion vectors, I did not see any 'pictural' reason for these
large vectors. It would be worthwhile investigating the idea of Peter of
preventing drifting. However, this is where it stops for me. I am desinging
multimedia processors and I found out that I have to count on large motion
vectors any time.

Thanx again
Cor
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