[FFmpeg-devel] graph.{html,css} embed failure on Windows build

[softworkz .]

> -----Original Message-----
> From: Kacper Michajlow <kasper93 at gmail.com>
> Sent: Sunday, June 15, 2025 12:49 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Cc: softworkz at hotmail.com
> Subject: graph.{html,css} embed failure on Windows build
> 
> Hello,
> 
> Since the recent addition of resman.c and embedding of graph.{html,css}
> some of the Windows builds fail. There seems to be a regression in path
> joining, caused by \ / mismatch.
> 
> Generally those issues were never a problem and I would prefer to keep it this
> way. This configuration has always been flaky and undertested.
> I could set-up a pipeline to report to the fate server if that's something that
> would help stabilize it.
> 
> Example of failure:
> ```
> BIN2C fftoolsresourcesgraph.html.c
> BIN2C fftools/resources/graph.html.c
> SED fftoolsresourcesgraph.css.min
> sed: can't read /c/a/FFmpeg/FFmpeg/fftoolsresources/graph.css: No such file
> or directory SED fftools/resources/graph.css.min
> make: *** No rule to make target 'fftools\resources\graph.html.c', needed by
> 'fftools/resources/graph.html.o'. Stop.
> make: *** Waiting for unfinished jobs....
> HOSTCC tests/videogen.o
> rm fftools\resources\graph.css.min fftools/resources/graph.html.c ```
> 
> Note that BIN2C is called twice, once with the correct path and with the
> wrong one.
> 
> Removing resman.c fixes the build. This has to be done forcefully in the code,
> because there is no configure option to disable this html/css embedding.
> 
> You can see the details and whole failing build logs here:
> code: https://github.com/kasper93/FFmpeg/tree/gha
> build:
> https://github.com/kasper93/FFmpeg/actions/runs/15653223193/job/44100
> 735119
> command: $ ../configure --enable-gpl --enable-version3 --enable-nonfree --
> samples=../samples --enable-memory-poisoning
> --arch=amd64 --enable-w32threads --as=clang --ar=llvm-ar --cxx=clang++ --
> ld=lld-link --windres=llvm-windres --strip=llvm-strip --cc=clang --nm=llvm-nm
> --extra-ldflags='msvcrt.lib oldnames.lib'
> --host_extralibs='' --toolchain=msvc && make -j`nproc` && make -j`nproc`
> run-checkasm && make -j`nproc` fate-rsync && make -j`nproc` fate
> 
> Here is exactly the same pipeline with removed graph.{html,css}
> https://github.com/kasper93/FFmpeg/tree/gha2
> https://github.com/kasper93/FFmpeg/actions/runs/15656127992
> Builds just fine.
> Ignore win32 (windows-11-arm, arm64, --toolchain=msvc) failure, as this is
> affected by unrelated regression in dxvenc.c on arm64 target, but the build
> itself is passing just fine.
> 
> Any ideas how we can restore the ability to build ffmpeg on Windows?

Hi Kasper,

I was able to reproduce the issue by adding a new CI build (for PRs to 
ffstaging/ffmpeg (on GitHub, not yet for Patchwork).

It appears to be all about dir separators when building under MSYS2 with 
Clang. Clang insists on using backslashes (unlike GCC and MSVC) and that
screws the Gnu make logic (pattern rules, dependency and up-to-date
checks).

If you need a quick unblock regarding compilation, you can try the commit
from this PR: https://github.com/ffstaging/FFmpeg/pull/100

It builds successfully, but FATE tests are failing (endless loop):
https://dev.azure.com/githubsync/ffmpeg/_build/results?buildId=95750&view=logs&j=275f1d19-1bd8-5591-b06b-07d489ea915a

Being off-site at the moment, I'm somewhat limited, but maybe It's helpful
for the moment, at least.

Best regards,
sw