add global offset setting (remove when we add timestamped input)

stepmania/src/PrefsManager.cpp

@@ -97,6 +97,7 @@ PrefsManager::PrefsManager()
 	m_bUseUnlockSystem = false;
 	m_bFirstRun = true;
 	m_bAutoMapJoysticks = true;
+	m_fGlobalOffsetSeconds = 0;
 	
 	/* DDR Extreme-style extra stage support.
 	 * Default off so people used to the current behavior (or those with extra
@@ -213,6 +214,7 @@ void PrefsManager::ReadGlobalPrefsFromDisk( bool bSwitchToLastPlayedGame )
 	ini.GetValue ( "Options", "LastSeenMemory",				m_iLastSeenMemory );
 #endif
 	ini.GetValueB( "Options", "AntiAliasing",				m_bAntiAliasing );
+	ini.GetValueF( "Options", "GlobalOffsetSeconds",		m_fGlobalOffsetSeconds );
 
 	m_asAdditionalSongFolders.clear();
 	CString sAdditionalSongFolders;
@@ -304,6 +306,7 @@ void PrefsManager::SaveGlobalPrefsToDisk()
 	ini.SetValue ( "Options", "LastSeenMemory",				m_iLastSeenMemory );
 #endif
 	ini.SetValueB( "Options", "AntiAliasing",				m_bAntiAliasing );
+	ini.SetValueF( "Options", "GlobalOffsetSeconds",		m_fGlobalOffsetSeconds );
 
 	/* Only write these if they aren't the default.  This ensures that we can change
 	 * the default and have it take effect for everyone (except people who

stepmania/src/PrefsManager.h

@@ -80,6 +80,7 @@ public:
 	bool			m_bUseUnlockSystem;
 	bool			m_bFirstRun;
 	bool			m_bAutoMapJoysticks;
+	float			m_fGlobalOffsetSeconds;
 
 	/* 0 = no; 1 = yes; -1 = auto (do whatever is appropriate for the arch). */
 	int				m_iBoostAppPriority;

stepmania/src/Song.cpp

@@ -28,6 +28,7 @@
 #include "TitleSubstitution.h"
 #include "BannerCache.h"
 #include "Sprite.h"
+#include "PrefsManager.h"
 
 #include "NotesLoaderSM.h"
 #include "NotesLoaderDWI.h"
@@ -148,7 +149,7 @@ void Song::AddLyricSegment( LyricSegment seg )
 float Song::GetMusicStartBeat() const
 {
 	float fBPS = m_BPMSegments[0].m_fBPM / 60.0f; 
-	return -m_fBeat0OffsetInSeconds*fBPS; 
+	return -(PREFSMAN->m_fGlobalOffsetSeconds+m_fBeat0OffsetInSeconds)*fBPS; 
 };
 
 void Song::GetBeatAndBPSFromElapsedTime( float fElapsedTime, float &fBeatOut, float &fBPSOut, bool &bFreezeOut ) const
@@ -156,6 +157,8 @@ void Song::GetBeatAndBPSFromElapsedTime( float fElapsedTime, float &fBeatOut, fl
 //	LOG->Trace( "GetBeatAndBPSFromElapsedTime( fElapsedTime = %f )", fElapsedTime );
 	// This function is a nightmare.  Don't even try to understand it. :-)
 
+	fElapsedTime += PREFSMAN->m_fGlobalOffsetSeconds;
+
 	fElapsedTime += m_fBeat0OffsetInSeconds;
 
 
@@ -225,7 +228,9 @@ void Song::GetBeatAndBPSFromElapsedTime( float fElapsedTime, float &fBeatOut, fl
 
 float Song::GetElapsedTimeFromBeat( float fBeat ) const
 {
-	float fElapsedTime = -m_fBeat0OffsetInSeconds;
+	float fElapsedTime = 0;
+	fElapsedTime -= PREFSMAN->m_fGlobalOffsetSeconds;
+	fElapsedTime -= m_fBeat0OffsetInSeconds;
 
 	for( unsigned j=0; j<m_StopSegments.size(); j++ )	// foreach freeze
 	{