Trouble with ffmpeg 7 and alternative VPY demuxer

[LigH]

During the last week(s) a problem started compiling ffmpeg including a patch to implement an alternative demultiplexer for VapourSynth.

This patch may be obsolete now, since there was some development in ffmpeg to allow dynamic linking of VapourSynth libraries in static builds, and some multi-threading optimizations.

To check whether the alternative demultiplexer can be removed as obsolete, it would be lovely if some people actually using VapourSynth under Windows could test these three builds I made (https://www.ligh.de/test/ffmpeg-vpy.7z); the latest EXE was built without the patch, the older two still contain it (they were built with MABS when there was no linker error yet). An additional task would be to benchmark the direct VPY source input versus piping from vspipe.

Your results will help deciding whether it is safe or not to exclude the alternative demultiplexer from building in MABS (https://github.com/m-ab-s/media-autobuild_suite/issues/2766) or possibly even disable VapourSynth support because there is not much advantage over piping.

[amayra]

i can help you with Linux testing if you went

[LigH]

The goal is to benchmark an ffmpeg binary with 0001-Add-Alternative-VapourSynth-demuxer.patch (https://raw.githubusercontent.com/m-ab-s/mabs-patches/master/ffmpeg/0001-Add-Alternative-VapourSynth-demuxer.patch) applied against one without. But right now it is not applicable. So you would need an older ffmpeg build which was compiled in a time when it did.

[Marsu42]

The goal is to benchmark an ffmpeg binary with 0001-Add-Alternative-VapourSynth-demuxer.patch (https://raw.githubusercontent.com/m-ab-s/mabs-patches/master/ffmpeg/0001-Add-Alternative-VapourSynth-demuxer.patch) applied against one without. But right now it is not applicable. So you would need an older ffmpeg build which was compiled in a time when it did.

Since I don't want to spam the bug tracker, continuing from https://github.com/m-ab-s/media-autobuild_suite/issues/2766#issuecomment-2362315870

None of the 3 ffmpeg exe with vapoursynth support work for me, I've put the 2 dll into the same directory, and using the very same .vpy with vspipe or loading into a media player (PotPlayer) works finde.

I might have done somthing wrong trying to load the .vpy with the ffmpeg you provided, but I have no idea what.

[LigH]

You will have to specify the input format explicitly (https://github.com/m-ab-s/media-autobuild_suite/issues/2766#issuecomment-2362448948) via -f because ffmpeg does not auto-detect that *.vpy files need the vapoursynth or vapoursynth_alt demuxer.

One benchmark has been submitted, reporting that vspipe is the fastest way and the alternative vapoursynth demuxer by far the slowest. So it appears that that one can be safely dropped...