[FFmpeg-devel] OpenCV filter should be built as C++, and C builds fail since OpenCV 3.4.1

Jan Ekström jeebjp at gmail.com
Mon Mar 19 19:01:49 EET 2018

On Mon, Mar 19, 2018 at 6:28 PM, wm4 <nfxjfg at googlemail.com> wrote:
> On Mon, 19 Mar 2018 09:35:22 -0400
> Jeff Cook <jeff.cook at strongstrata.com> wrote:
>> Hello,
>> Please see the bug report at https://github.com/opencv/opencv/issues/10963 , which discusses OpenCV's failure to build as pure C since upstream version 3.4.1, and also discusses how all modules that use OpenCV 2 or later should be compiled as C++ to avoid esoteric issues and serious breakages.
>> There is a large amount of discussion there that I don't want to needlessly duplicate and/or badly summarize here, but the high-level overview is that it seems that ffmpeg will need to convert avfilter/vf_opencv.c to build as C++ if the OpenCV filter is going to continue to work. The current situation is affecting many prominent projects like VLC.
> FFmpeg is a C project, and due to missing features in C++ (initializers)
> it's very awkward to build things in C++ mode. Can't OpenCV just fix
> their stuff.



They're breaking C compatibility knowingly. If and only if we want to
keep whatever features we get by linking against OpenCV, then the
correct mode of operation is to make that specific file compile as C++
and export the relevant C end points. Or maybe just link with the C++
side of things; whatever was done with libutvideo back in the day?

Unfortunately, fixing this will end up on whomever cares about this
functionality, since I don't think we have an active maintainer for
this component?

Best regards,

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