#11257: scale filters implementation of scale2ref broken on linux for ref_h or
rh
constants. works on windows.
---------------------------------+---------------------------------------
Reporter: mytait | Type: defect
Status: new | Priority: normal
Component: swscale | Version: unspecified
Keywords: scale | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Summary of the bug:
**short**: scale filter on linux can not parse the rh or ref_h constant.
in windows it works as intended. It seems it has been like this since at
least ffmpeg 4.4.1 (oldest version i tested!)
**longer**:
the scale-filter takes an input visual (video or image) and rescales the
input to a desired size. When 2 inputs are provided it replaces the old
scale2ref and uses the second input as reference. The size of the
reference is represented by the rh or ref_h constant.
see:
https://ffmpeg.org/ffmpeg-filters.html#Options-2
in windows the constant is recognized and used. the exact same command
works on windows. on linux it throws an error:
{{{
[Parsed_scale_0 @ 0x64e8d0ce8500] [Eval @ 0x7fff00113650] Undefined
constant or missing '(' in 'rh*0.5'
[Parsed_scale_0 @ 0x64e8d0ce8500] Cannot parse expression for height:
'rh*0.5'
}}}
its seems someone filed a related bug for the CUDA variant as well:
https://trac.ffmpeg.org/ticket/11174
as i am not able to compile ffmpeg i cant test this on 7.1. But i have
tested ffmpeg 4,5,6 and 7.0 so i think this has always been there?
How to reproduce:
{{{
% ffmpeg -y -i in_reffile.mkv -i in_main.mkv -filter_complex
"[1:v][0:v]scale=w=oh*dar:h=rh*0.5" -pix_fmt yuv420p outf4.mkv
#Works on windows with
#ffmpeg version 2024-08-07-git-94165d1b79-essentials_build-www.gyan.dev
#BROKEN on ubuntu linux with
#ffmpeg version 4.4.1 AMD64
#ffmpeg version 5.1.1 AMD64
#ffmpeg version 6.1.1 AMD64
#ffmpeg version 7.0.2 AMD64
#ffmpeg version 7.0.2 i386
}}}
Patches should be submitted to the ffmpeg-devel mailing list and not this
bug tracker.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11257>
FFmpeg <https://ffmpeg.org>
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