[FFmpeg-devel] [PATCH v3 2/2] libavformat/vapoursynth: Update to API version 4, load library at runtime

[Ramiro Polla]

On Sat, Aug 24, 2024 at 1:06 PM Stefan Oltmanns via ffmpeg-devel
<ffmpeg-devel at ffmpeg.org> wrote:
> Am 23.08.24 um 14:25 schrieb Ramiro Polla:
> >
> > I finally managed to test the patches on a real Windows system.
> >
> > They both look good to me, I'll apply them in a couple of days if
> > there are no other comments.

Applied. Thank you for the patches.

> > It would be helpful to write a page in the trac wiki with a basic
> > howto and common pitfalls. I had problems installing python and
> > vapoursynth for my user only, and then for all users on the Windows
> > machine. I had to uninstall everything, remove some registry keys, and
> > try again using administrator to install to all users. I also had to
> > manually install Microsoft Visual C++ Redistributable. There was no
> > good error message telling me what was going wrong. When I added an
> > av_log() with FormatMessage() after LoadLibraryW() failed, the error
> > message was also unhelpful.
>
> Just to make that clear: You had problem installing Python/VapourSynth
> on Windows, not with the patch? I know Python can be somewhat
> problematic on Windows from other contexts, but VapourSynth is usually
> straight forward.

Yes, it was unrelated to the patch.

> The install guide for VapourSynth lists some problems you may have
> experienced:
>
> http://www.vapoursynth.com/doc/installation.html#windows-installation
>
> -Both Python and VapourSynth must be installed as either current user or
> all users/system
> -On current user installs it cannot install the required Microsoft
> Visual C++ Redistributable
>
> To ensure installation of VapourSynth worked you can run "vspipe -v",
> this will show the installed version if it's working or an error message
> if not.
>
> Common issue on Linux/macOS is that the Python package cannot be found,
> you have to set PYTHONPATH for example like this:
> PYTHONPATH=/usr/local/lib/python3.12/site-packages
> ffmpeg will display the PYTHONPATH issue as a possible problem if can
> find the vapoursynth library, but not initialize it.
>
> On recent versions of macOS, it will not look for libraries in
> /usr/local/lib anymore, you may have to set
> DYLD_LIBRARY_PATH=/usr/local/lib

Something like this could be added to the wiki.