Add new preference: DefaultGroupOffsetSeconds to dictate the default sync bias on the machine when no group.ini is present (or if there is no SyncOffset field in said file).

- Generally Supports either ITG (9ms) or NULL (0ms).
- Alternatively, one could edit the preference manually to put a different value
- Name/Description probably worth ironing out

src/Group.cpp

@@ -43,7 +43,7 @@ Group::Group(const RString sDir, const RString &sGroupDirName) {
     RString Series = "";
     RString bannerPath = "";
     RString authorsNotes = "";
-    float fOffset = 0;
+    float fOffset = PREFSMAN->m_fDefaultGroupOffsetSeconds;
 
     if (FILEMAN->DoesFileExist(sGroupIniPath)) {
         IniFile ini;
@@ -65,12 +65,14 @@ Group::Group(const RString sDir, const RString &sGroupDirName) {
         RString sValue = "";
         
         ini.GetValue("Group", "SyncOffset", sValue);
-        if (sValue.CompareNoCase("null") == 0) {
-            fOffset = 0;
-        } else if (sValue.CompareNoCase("itg") == 0) {
-           fOffset = 0.009f;
-        } else {
-            fOffset = StringToFloat(sValue);
+        if (!sValue.empty()) {
+            if (sValue.CompareNoCase("null") == 0) {
+                fOffset = 0.0f;
+            } else if (sValue.CompareNoCase("itg") == 0) {
+            fOffset = 0.009f;
+            } else {
+                fOffset = StringToFloat(sValue);
+            }
         }
         ini.GetValue("Group", "Year", m_iYearReleased);
         ini.GetValue( "Group", "Credits", credits );

src/PrefsManager.cpp

@@ -237,6 +237,7 @@ PrefsManager::PrefsManager() :
 	m_ShowDancingCharacters		( "ShowDancingCharacters",		SDC_Random ),
 	m_bUseUnlockSystem		( "UseUnlockSystem",			false ),
 	m_fGlobalOffsetSeconds		( "GlobalOffsetSeconds",		-0.008f ),
+	m_fDefaultGroupOffsetSeconds	( "DefaultGroupOffsetSeconds",		0.0f ),
 	m_iProgressiveLifebar		( "ProgressiveLifebar",			0 ),
 	m_iProgressiveStageLifebar	( "ProgressiveStageLifebar",		0 ),
 	m_iProgressiveNonstopLifebar	( "ProgressiveNonstopLifebar",		0 ),

src/PrefsManager.h

@@ -240,6 +240,7 @@ public:
 	Preference<ShowDancingCharacters>		m_ShowDancingCharacters;
 	Preference<bool>	m_bUseUnlockSystem;
 	Preference<float>	m_fGlobalOffsetSeconds;
+	Preference<float>	m_fDefaultGroupOffsetSeconds;
 	Preference<int>	m_iProgressiveLifebar;
 	Preference<int>	m_iProgressiveStageLifebar;
 	Preference<int>	m_iProgressiveNonstopLifebar;

src/ScreenOptionsMasterPrefs.cpp

@@ -710,6 +710,12 @@ static void GlobalOffsetSeconds( int &sel, bool ToSel, const ConfOption *pConfOp
 	MoveMap( sel, pConfOption, ToSel, mapping, ARRAYLEN(mapping) );
 }
 
+static void DefaultGroupOffsetSeconds( int &sel, bool ToSel, const ConfOption *pConfOption )
+{
+	const float mapping[] = { 0.0f, 0.009f };
+	MoveMap( sel, pConfOption, ToSel, mapping, ARRAYLEN(mapping) );
+}
+
 static void EditRecordModeLeadIn(int &sel, bool to_sel, const ConfOption* conf_option)
 {
 	float mapping[32];
@@ -941,6 +947,7 @@ static void InitializeConfOptions()
 			c.AddOption( ssprintf("%+i ms", i) );
 		ADD( c );
 	}
+	ADD( ConfOption( "DefaultGroupOffsetSeconds",			DefaultGroupOffsetSeconds,		"Null","|ITG" ) );
 	ADD( ConfOption( "EnableAttackSounds",		MovePref<bool>,		"No","Yes" ) );
 	ADD( ConfOption( "EnableMineHitSound",		MovePref<bool>,		"No","Yes" ) );
 	ADD( ConfOption( "RateModPreservesPitch",		MovePref<bool>,		"No","Yes") );

src/SongManager.cpp

@@ -418,8 +418,6 @@ void SongManager::LoadSongDir( RString sDir, LoadingWindow *ld, bool onlyAdditio
 				const std::vector<Steps*>& vpSteps = pNewSong->GetAllSteps();
 				for (Steps* s : vpSteps)
 				{
-					// Empty TimingData means it's inherited
-					// from the song and is already changed.
 					if( s->m_Timing.empty() )
 						continue;
 					s->m_Timing.m_fBeat0GroupOffsetInSeconds = group->GetSyncOffset();