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

[Vitor Sessak]

Hi

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?

-Vitor