Supplying compilation flags

[shawngmc]

I'm in a mood to do some benchmarking, and I was wondering if there's a good way to feed -march flags, etc.

I've been somewhat enamored by the psABI x86_64 levels lately. I know for many things they would make no difference, but AVX2/AVX512 should make a substantial difference for video decoding/encoding. I'm trying to make a reproducible build to test, and I assume that I'll also want to build the library dependencies with similar compiler flags. I was looking at making a Dockerfile of my own, but your Dockerfiles are excellent, and ubuntu2404-edge seems to be a great starting point.

I don't see any straightforward way to add something like that to your build scripts without copying the whole ubuntu2404-edge and modifying each library build and the ffmpeg build.

For example, for another project using CMake, I'm currently setting an arch via:

ARG ARCH=x86-64-v2
ENV ARCH=${ARCH}
#...
RUN echo -e "set(CMAKE_C_FLAGS \"${CMAKE_C_FLAGS} -march=$ARCH\")" >> ./CMakeLists.txt && \
    echo -e "set(CMAKE_CXX_FLAGS \"${CMAKE_CXX_FLAGS} -march=$ARCH\")" >> ./CMakeLists.txt

Is there anything I'm missing? Alternatively, is this something that there would be interest in contributing back?