[FFmpeg-trac] #706(avfilter:closed): scale filter doesn't understand »out_h«
FFmpeg
trac at avcodec.org
Tue Dec 6 15:13:38 CET 2011
#706: scale filter doesn't understand »out_h«
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Reporter: taeuber | Owner:
Type: defect | Status: closed
Priority: normal | Component: avfilter
Version: git-master | Resolution: fixed
Keywords: scale | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 1 |
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Changes (by saste):
* status: new => closed
* resolution: => fixed
Comment:
Replying to [comment:4 taeuber]:
> What/who does »ow« or »oh« define?
oh and ow are useful if you want to reference ow/oh in the other
expressions, for example to get a square output:
scale=2*iw:ow
in this case you define ow in the first expression, and reference it in
the second expression, in a similar way you can do:
scale=oh:2*ih
what you can do is to self-reference ow/oh in the corresponding
expression.
> Other filters?
>
> Are »ih« and »iw« changed by the scale filter?
No they are the input width and height, which are fixed.
> I thought before any filters apply that "ow=iw" and "oh=ih". And the
crop filter for instance changes the "oh" and "ow" automatically by
subtracting the cropped lines/rows.
> Wouldn't this make sense?
That's possible, but I think the current behavior is not completely
misguided, expressing something like
x=x is inherently confusing, better to just say explicitely scale=iw:ih/2.
> Thanks
I clarified the error message in:
{{{
commit 3af5ddb24b91cfa6e2392b85ef1beafda7e85225
Author: Stefano Sabatini <stefasab at gmail.com>
Date: Sun Dec 4 23:33:40 2011 +0100
vf_scale: give a clue in case of invalid expression self-reference
Address trac ticket #706.
}}}
changing status to closed, please provide a patch or suggest if you think
this behavior can be clarified/improved.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/706#comment:5>
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