[x264-devel] The size of search area in reference frames

[john sisi]

Thanks for the reply. Since moving objects can move further over a
larger interval of time, so a larger search area must be used for
motion estimation. The larger the search area, the higher the
computational complexity. In other words, assuming that the size of
the search window (for either fullpel or quarterpel motion estimation)
in the first reference frame is 32x32, this size in the second
reference frame must be about 64x64 (assuming that objects has a
linear speed) and so on.

But as you mentioned, x264 always uses a fixed window size (or maximum
search range or vector size) on all reference frames which I think is
not an efficient strategy. But am I right?

John

On Sun, Jun 13, 2010 at 11:15 PM, Jason Garrett-Glaser
<darkshikari at gmail.com> wrote:
> On Sun, Jun 13, 2010 at 10:54 PM, Radek Czyz <radoslaw at syskin.cjb.net> wrote:
>> On 14/06/2010 2:45 PM, john sisi wrote:
>>>
>>> Hi All,
>>>
>>> As you may know better, due to the movement of objects, the search
>>> area for motion estimation in reference frames must be increased in
>>> order to achieve better PSNR performance. But it seems that x264
>>> doesn't increase the size of the search area in the reference frames
>>> and it always uses the same size. But am I right? If not, please
>>> correct me by showing where this issue is handled. Thanks,
>>>
>>> John
>>
>> Hi,
>>
>> Since you're asking for details of x264, can you describe your question more
>> in terms of x264's workings?
>>
>> Particularly, what is this "search area" (do you mean during fullsearch
>> only?) and from what it should be increased (that is, why was "it" decreased
>> in the first place).
>>
>> x264 has maximum vector size as part of its configuration but, as its name
>> suggests, it's already a maximum allowed, and it's up to the user to
>> increase it if he wants to allow more.
>
> x264 by default uses the maximum allowed by the spec (for maximum
> vector size).  The user can't ask for more.
>
> Dark Shikari
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