As part of the code cleanup efforts, the internal libfaad2 copy has been removed since the FFmpeg decoder is working well. Also the internal mp3lib copy is no longer used by default since the many alternatives (FFmpeg, libmpg123, libmad) avoid its recurring issues like incorrect decoding with newer compilers. However it can still be forced at runtime for easier tracking of regressions. Please do not rely on this since it will be removed in the future. If you do not actually need it consider disabling it at compile time with --disable-mp3lib.