[Slackbuilds-users] OpenCV SlackBuild bug - Was: ffmpeg does not compile with opencv 3.4.1

[Christoph Willing]

On 16/03/18 23:48, Ythogtha wrote:
>> Thanks all for spotting the problem. I've just pushed a fix for it.
>>
>> While working through this myself, I noticed that the requirement for
>> python3 to generate a python3 binding no longer works unless numpy3 is
>> also installed at build time. Since numpy3 requires python3, I've
>> replaced the requirement for python3 with numpy3.
>>
>> Back to the original problem of building ffmpeg with opencv support, I
>> haven't been able to compile that successfully. The configure phase
>> finds opencv OK but compilation fails with:
>>
>> In file included from /usr/include/opencv2/core/types_c.h:59:0,
>>                  from /usr/include/opencv2/core/core_c.h:48,
>>                  from libavfilter/vf_libopencv.c:28:
>> /usr/include/opencv2/core/cvdef.h:485:1: error: unknown type name
>> 'namespace'
>>  namespace cv {
>>  ^
>> /usr/include/opencv2/core/cvdef.h:485:14: error: expected '=', ',', ';',
>> 'asm' or '__attribute__' before '{' token
>>  namespace cv {
>>               ^
>> common.mak:60: recipe for target 'libavfilter/vf_libopencv.o' failed
>> make: *** [libavfilter/vf_libopencv.o] Error 1
>>
>>
>> It's not something I want to spend a lot of time trying to fix - for my
>> own use I have the dependency the other way around by building opencv
>> with ffmpeg support. However if anyone can propose a fix, I'm happy (and
>> grateful) to include it in the SlackBuild.
>>
>> chris
> 
> Hi!
> 
> 	I just went back into this, used your updated build for OpenCV and
> failed to compile ffmpeg.
> Then I found this :
> https://github.com/opencv/opencv/issues/10963
> 	So I modified the file /usr/include/opencv2/core/cvdef.h according to
> what's said there.
> And well, it works fine.
> ffmpeg compiles and runs perfectly.
> 
> 	So maybe including a patch to OpenCV since this seems to affect other
> softwares, like VLC apparently ?
> Your call Chris :)
> 

I just missed the cut off for the SBo update - it included only the
partial fix mentioned previously.

I'll check the additional cvdef.h patch and include it in the next
update. Thanks for finding it.

chris