libchromaprint circle dependency with ffmpeg

[kwizart]

This is Fedora/RPM Fusion package maintainer advice request.

In Fedora, chromaprint now is build with ffmpeg enabled. On the other hand, ffmpeg also has libchromaprint enabled. This lead to a circle dependency.

Nothing that cannot be workaround on the packaging side but still annoying to deal with... (At least until libchromaprint is not used in a process built with a different ffmpeg version)...

I wonder if it can be possible to fix the issue by moving the few functions using libavcodec/libavutils from the library to the binary using it ?

[lalinsky]

@kwizart This is an unfortunate situation. Using the ffmpeg binary from chromaprint is not an option.

There are two uses of FFmpeg:

• libchromaprint - it needs FFT functions from libavcodec, there is no way to do this via the ffmpeg binary, this is a very low level API
• fpcalc - it needs libavformat/libavcodec/libswscale for decoding audio files. while it could be theoretically possible to use the ffmpeg binary, I don't really want to do it, because the main deployment platform for fpcalc are standalone/static binaries built by me and calling another external process would be a big no-no there.

If the circular dependency is a problem, I'd suggest disabling the chromaprint filter in FFmpeg. It's not a commonly used feature and people who really need it can build FFmpeg themselves. It's far more common for applications to use the fpcalc binary to generate audio fingerprints.

If you want to resolve it, you would need to split the chromaprint package into two internally.

The first one only builds libchromaprint with fftw as the FFT library. It will not link to FFmpeg at all in that case.

Then you can build FFmpeg against libchromaprint.

And then you can build fpcalc against libchromaprint and libav* libraries.