Currently, SFML_Audio depends on OpenAL-Soft and libsndfile which are LGPL and therefore don't permit static linking with closed-source applications. For some developers neither releasing source codes nor dynamic linking is acceptable for various reasons. Those developers are not able to use SFML_Audio and have to rely on other cross-platform audio solutions instead. One of such solutions is PortAudio. Still it would be much more preferable if low-level PortAudio library was wrapped by a more friendly library like SFML_Audio. Certainly, PortAudio does not natively support advanced features like 3D spatialization but those features are not used very often. Anyway, those missing functions could be possible to implement, or otherwise, there could be two versions of SFML_Audio: "classic" version using OpenAL that provides advanced functionality and "lite" version using PortAudio that is not bound by LGPL limitations.
As for libsndfile, I don't really understand why is it needed at all. Hardly anybody needs any formats besides OGG/Vorbis and WAV/PCM, where the former is handled by stb_vorbis and the latter is simple enough to be decoded without any external libraries. Additionally, BSD-licensed libFLAC might be useful for FLAC support.
Thanks.
