Initial commit

added libraries:
opus
flac
libsndfile

updated:
libvorbis
libogg
openal

- Everything works as expected for now. Bare in mind libsndfile needed the check for whether or not it could find the xiph libraries removed in order for this to work.

Engine/lib/openal-soft/common/alcomplex.h

@@ -2,6 +2,7 @@
 #define ALCOMPLEX_H
 
 #include <complex>
+#include <type_traits>
 
 #include "alspan.h"
 
@@ -10,21 +11,27 @@
  * FFT and 1 is inverse FFT. Applies the Discrete Fourier Transform (DFT) to
  * the data supplied in the buffer, which MUST BE power of two.
  */
-void complex_fft(const al::span<std::complex<double>> buffer, const double sign);
+template<typename Real>
+std::enable_if_t<std::is_floating_point<Real>::value>
+complex_fft(const al::span<std::complex<Real>> buffer, const al::type_identity_t<Real> sign);
 
 /**
  * Calculate the frequency-domain response of the time-domain signal in the
  * provided buffer, which MUST BE power of two.
  */
-inline void forward_fft(const al::span<std::complex<double>> buffer)
-{ complex_fft(buffer, -1.0); }
+template<typename Real, size_t N>
+std::enable_if_t<std::is_floating_point<Real>::value>
+forward_fft(const al::span<std::complex<Real>,N> buffer)
+{ complex_fft(buffer.subspan(0), -1); }
 
 /**
  * Calculate the time-domain signal of the frequency-domain response in the
  * provided buffer, which MUST BE power of two.
  */
-inline void inverse_fft(const al::span<std::complex<double>> buffer)
-{ complex_fft(buffer, 1.0); }
+template<typename Real, size_t N>
+std::enable_if_t<std::is_floating_point<Real>::value>
+inverse_fft(const al::span<std::complex<Real>,N> buffer)
+{ complex_fft(buffer.subspan(0), 1); }
 
 /**
  * Calculate the complex helical sequence (discrete-time analytical signal) of