[FFmpeg-soc] [soc]: r1932 - libavfilter/vf_scale.c

[Michael Niedermayer]

On Sun, Mar 02, 2008 at 06:11:10PM +0100, Vitor Sessak wrote:
> Hi
> 
> Bobby Bingham wrote:
> > On Sun, 02 Mar 2008 15:00:34 +0100
> > Vitor Sessak <vitor1001 at gmail.com> wrote:
> >> Bobby Bingham wrote:
> >>> On Thu, 28 Feb 2008 00:18:59 +0100 (CET)
> >>> koorogi <subversion at mplayerhq.hu> wrote:
> >>>
> >>>> Author: koorogi
> >>>> Date: Thu Feb 28 00:18:58 2008
> >>>> New Revision: 1932
> >>>>
> >>>> Log:
> >>>> Slice support for vf_scale.
> >>>>
> >>>>
> >>>> Modified:
> >>>>    libavfilter/vf_scale.c
> >>>>
> >> [...]
> >>
> >>> After some more testing, it seems this doesn't work right with
> >>> --enable-swscaler. I'll take a closer look at it later tonight.
> >> I was wondering one thing: imagine doing a 200x200 -> 400x400 linear 
> >> interpolation resizing.
> >>
> >> The filter gets as input a (for ex.) 4x100 slice. It can then 
> >> interpolate the line numbers (1,2,3,4,5,6,7) of the output. For the
> >> next slice, it would be able to output the lines
> >> (9,10,11,12,13,14,15). But to evaluate the output line 8, it'll need
> >> both the input line 4 and 5. So to do slice-based resizing, it would
> >> be necessary a complicated, resize algorithm dependent, caching. Also
> >> it would require some kind of memcpy.
> >>
> >> So my opinion is that implementing slices in resizing is hard and
> >> maybe not worth the effort. In the other hand, colospace conversion
> >> should be pretty simple. Or am I missing something?
> >>
> > 
> > I believe that this caching is already implemented by libswscale.

yes, swscale will do the horizontal scaling into a ring buffer of lines
and then use that to do vertical scaling


> 
> Does imgresample.c also support this?

no, imgresample is trash

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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