unnecessary and problematic dependency on C++

[andrewrk]

This project depends on C++ but it doesn't need to. In a music player project with otherwise a lot of C dependencies, this is the only C++ dependency and the only thing that makes my music player need to link against libc++, which brings a lot of problems.

FFmpeg for example is a large C project that does not have a libc++ dependency. It also has support for chromaprint integration, but if you enable that integration, it makes FFmpeg depend on libc++.

It also seems like this project implements a lot of FFmpeg internally. Filtering, resampling, normalizing, fft, etc.

Would you consider some of these things?

1. Convert to plain C to offer a library that avoids requiring users bring an unwanted C++ dependency.
2. Directly maintain an implementation of the chromaprint algorithm upstream in FFmpeg so that it has chromaprint support without integrating with an external library. It looks like a lot of boilerplate/wrapping code could be deleted.

Such things would make my music player:

• easier for contributors to build from source
• build from source faster
• smaller binary size
• more portable (libc++ is less portable than libc)

[lalinsky]

I'm not really planning to do conversion to C. If you really want it and are willing to implement it yourself, I'm open to review the code and help with testing the compatibility.