Re: [FFmpeg-devel] [PATCH v2] libavformat/vapoursynth: Update to API version 4, load library at runtime

[Stefan Oltmanns via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

Hello,

I adressed the issues/concerns that were raised with the first revision
of the patch.
Any feedback? Did I do something wrong?

Best regards
Stefan


Am 06.07.24 um 23:08 schrieb Stefan Oltmanns via ffmpeg-devel:
> Hello,
>
> this is revised patch, to sum up the changes:
>
> The current VapourSynth implementation is rarely used, as it links the
> VapourSynth library at build time, making the resulting build unable to
> run when VapourSynth is not installed. Therefore barely anyone compiles
> with VapourSynth activated.
>
> I changed it, so that it loads the library at runtime when a VapourSynth
> script should be opened, just like AviSynth does.
> On Windows the DLL from VapourSynth is not installed in the system
> directory, but the location is stored in the Registry. Therefore I added
> some code to read that information from the registry.
>
> As the V4 API is designed with dynamic loading in mind (only a single
> import), I updated the implementation to V4 (changes are mostly
> superficial, no structural changes). The V4 API is already several years
> old, fully supported since R55 released in 2021.
>
>
> Changes from first patch:
> -Separated the Windows-specific function for getting the DLL location
> from the platform-specific includes
> -It is not enabled by default in configure
> -The header files are not included anymore
>
>
> I would like to include the header files for this reason:
> While most Linux distributions ship ffmpeg, only very few contain
> VapourSynth. Therefore ffmpeg won't be compiled with VapourSynth support
> by these distributions, because no VapourSynth headers. Including the
> headers in ffmpeg would mean they can compile with VapourSynth support
> and if a user decided to install VapourSynth from somewhere else or
> compile it by himself, ffmpeg support would be ready and no need for the
> user to install another ffmpeg or compile one.
> I'm not sure what the rules for shipping include files are, as there are
> a few 3rd-party include files in ffmpeg. License is not an issue
> (Vapourynth is LGPL v2.1 or later like ffmpeg).
>
>
>
> make fate runs without any issue. I tested VapourSynth input scripts
> with various color formats on different platforms:
>
> Ubuntu 22.04
> macOS 13 (x86_64)
> macOS 13 (arm64)
> Windows 10 (msys2/gcc)
>
> It compiles on these platforms without any warning and runs without any
> issues.
>
> Best regards
> Stefan
>
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