add ReplayGainReferenceLoudness constant

include/share/replaygain_analysis.h

@@ -44,11 +44,13 @@ extern "C" {
 
 typedef float   Float_t;         /* Type used for filtering */
 
+Float_t ReplayGainReferenceLoudness; /* in dB SPL, currently == 89.0 */
+
 int     InitGainAnalysis ( long samplefreq );
 int     AnalyzeSamples   ( const Float_t* left_samples, const Float_t* right_samples, size_t num_samples, int num_channels );
 int		ResetSampleFrequency ( long samplefreq );
-Float_t   GetTitleGain     ( void );
-Float_t   GetAlbumGain     ( void );
+Float_t GetTitleGain     ( void );
+Float_t GetAlbumGain     ( void );
 
 #ifdef __cplusplus
 }

src/share/replaygain_analysis/replaygain_analysis.c

@@ -100,6 +100,8 @@
 
 #include "replaygain_analysis.h"
 
+extern Float_t ReplayGainReferenceLoudness = 89.0; /* in dB SPL */
+
 typedef unsigned short  Uint16_t;
 typedef signed short    Int16_t;
 typedef unsigned int    Uint32_t;