[x264-devel] Re: Regarding quarter pixel ME

[mahesh k]

Dear,

What i mean was,,,First I calculated integer level best motion vector using
SAD as error criterion. that is the one (block) which gives minimum SAD . In
this blk size is 16 x 16 and reference frame is previous frame(non
interpolated)

Then surrounding best integer level motion vector I choosed the eight half
pixel locations and searched for the besxt match among this using SAD as the
criterion. In this case also blk size was 16 x16. Now I compared the minimum
SAD in both cases and if half pixel min SAD is best then I will go for
quarter pixel level....In half and quarter pixel level the blk size was 16
x16 but the reference frame was previous frame interpolated upto quarter
pixel level.

Ex:

curr blk to be matched (2x2)

100   102

90      95

Reference (non interpolated):

80     83    95    100

100    40    60     75

120     60    80     90

90      50     70    88


Reference (non interpolated) used as reference for integer pixel ME.

80     83    95    100

100    40    60     75

120     60    80     90

90      50     70    88

Reference (interpolated) frame used as reference for half and quarter pixel
ME.

 I      Q     H     Q    I      Q    H    Q     I
80    82    81    82  83    86   89   85    95   93   97   98   100

100   85   70    55   40   45   50   55    60   64   68    72     75

120  105   90   75   60    65   70   75    80   83   84   88      90

90     60   70   40    50   55    60   65    70   75  79   84       88

This is how i implemented ....

Regards,
Maheshwar.


On 3/29/07, Radek Czyz <radoslaw at syskin.cjb.net> wrote:
>
> Hi, can you explain more clearly? It's not ME that gives you SAD - it's
> SAD that can be used to perform ME. The other way around ~
>
> mahesh k wrote:
> > Ok, thx for ur reply.....Can u plz tell me whether the quarter pixel ME
> > will give the min SAD for all the macroblocks within a frame.? Also plz
> > tell me where I can find the test results regarding this?
> >
> > regards,
> > mahesh
> >
> > On 3/28/07, *Radek Czyz* <radoslaw at syskin.cjb.net
> > <mailto:radoslaw at syskin.cjb.net>> wrote:
> >
> >      > U plz tell me whether this was correct or not.
> >
> >     Well yeah, it's a good (although wasteful in terms of memory) way of
> >     doing it.
> >
> >     You ask for "correct" but ME is never defined, so all methods are
> >     "correct". Just some are more efficient (give better or faster
> result)
> >     than others.
> >
> >     mahesh k wrote:
> >      > I went through the JM reference code but I was not able to
> understand
> >      > it. Recently i implemented quarter pixel motion estimation. First
> I
> >      > interpolated the whole reference frame upto quarter pixel level
> and
> >      > stored this in a buffer. Then  I found the integer pixel motion
> >     vector
> >      > using the previos frame as reference frame (non interpolated
> >     reference
> >      > frame) and the search criterion i used was SAD. Then I performed
> >     the sub
> >      > pixel refinement using the best integer pixel motion vector
> >     coordinates
> >      > as center using the quarterly interpolated frame as reference.
> >      >
> >      > U plz tell me whether this was correct or not.
> >      >
> >      > Regards,
> >      > Mahesh.
> >      >
> >      > On 3/28/07, *Tomas Carnecky* <tom at dbservice.com
> >     <mailto:tom at dbservice.com>
> >      > <mailto: tom at dbservice.com <mailto:tom at dbservice.com>>> wrote:
> >      >
> >      >     mahesh k wrote:
> >      >      > I didnot get u exactly..Can u tell me in detail...
> >      >      >
> >      >
> >      >     RTFM means 'Read The Fucking Manual', see[1]. He replaced the
> >     'M' with a
> >      >     'S' which he afterwards explained to be, quote, 'sourcecode
> or
> >      >     standard'. That means, he was trying to tell you 'Read The
> F***
> >      >     sourcecode' or Read The F*** standard'.
> >      >     IOW (you can use wikipedia, too,  to look up what that
> >     means), he told
> >      >     you to read the sourcecode (which is freely available) or the
> >     H.264
> >      >     standard. The information you're looking for is in both
> >     locations,
> >      >     hence, quote, 'your choice'.
> >      >
> >      >      >
> >      >      > On 3/27/07, *Loren Merritt* <lorenm at u.washington.edu
> >     <mailto:lorenm at u.washington.edu>
> >      >     <mailto: lorenm at u.washington.edu
> >     <mailto:lorenm at u.washington.edu>>
> >      >      > <mailto: lorenm at u.washington.edu
> >     <mailto:lorenm at u.washington.edu>
> >      >     <mailto:lorenm at u.washington.edu
> >     <mailto:lorenm at u.washington.edu> >>> wrote:
> >      >      >
> >      >      >     On Tue, 27 Mar 2007, mahesh k wrote:
> >      >      >
> >      >      >     > Can any one plz tell me how to choose the refernece
> >     frame for
> >      >      >     > integer level and quarter pixel motion estimation.
> >      >      >
> >      >      >     RTFS. (sourcecode or standard, your choice)
> >      >      >
> >      >
> >      >     tom
> >      >
> >      >     [1] http://en.wikipedia.org/wiki/RTFM
> >     <http://en.wikipedia.org/wiki/RTFM>
> >      >
> >      >     --
> >      >     This is the x264-devel mailing-list
> >      >     To unsubscribe, go to:
> http://developers.videolan.org/lists.html
> >      >
> >      >
> >
> >     --
> >     This is the x264-devel mailing-list
> >     To unsubscribe, go to: http://developers.videolan.org/lists.html
> >
> >
>
> --
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>
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