[x264-devel] Max number of motion vectors

[BugMaster]

On Thu, 12 May 2016 22:19:24 +0000, Li, Stephen wrote:
> Thanks for your response. Removing p4x4 fixes the problem. Is it a
> known issue with x264? What is the effect of removing p4x4?

> Thanks
> Steve

It is known that with p4x4 we can in theory violate this level
constraint. But imho it is really stupid constraint of higher levels
(3.1+) while lower levels allow up to 64 MVs per 2 consecutive MBs
i.e. hardware still need to support this number of MVs and this
constraint is only stupid performance micro optimization at higher
bitrates (levels) for very slow decoders (1-gen H.264 devices?). There
is no known issue with it at any real device. But if you stream
analyzer so picky and you need to conform to it you can disable p4x4.
It will disable use of partitions with 4x4, 4x8 and 8x4 sizes.