diff --git a/sync.cc b/sync.cc
index a68d015..1761677 100644
--- a/sync.cc
+++ b/sync.cc
@@ -65,9 +65,9 @@ float T_SyncData::T_VarHelper_::valueAt(
 	const float et( ( segStarts[ s ] + seg.durations[ pid ] ) * units );
 	const float v0 = ( position - st ) / ( et - st );
 	float v = v0;
-	if ( seg.type != E_SyncSegment::LINEAR ) {
+	if ( seg.type != T_SyncSegment::LINEAR ) {
 		v *= v0;
-		if ( seg.type == E_SyncSegment::SMOOTH ) {
+		if ( seg.type == T_SyncSegment::SMOOTH ) {
 			v *= 3 - 2 * v0;
 		}
 	}
diff --git a/sync.hh b/sync.hh
index 079751f..8e7c6ef 100644
--- a/sync.hh
+++ b/sync.hh
@@ -4,25 +4,134 @@
 #endif
 
 
-enum class E_SyncSegment
+// Definition of a single input - id & range
+struct T_SyncInputDfn
 {
-	LINEAR ,
-	RAMP ,
-	SMOOTH ,
-	//HERMITE
+	std::string identifier;
+	float min = -std::numeric_limits< float >::infinity( ),
+	      max = std::numeric_limits< float >::infinity( );
+
+	T_SyncInputDfn( __rd__ std::string const& identifier ,
+			__rd__ const float min ,
+			__rd__ const float max ) noexcept
+		: identifier( identifier ) , min( min ) , max( max )
+	{ }
+};
+using P_SyncInputDfn = std::unique_ptr< T_SyncInputDfn >;
+
+/*============================================================================*/
+
+// Definition of UI overrides for inputs
+struct T_SyncUIOverride
+{
+	enum E_Type {
+		FLOAT , VEC2 , VEC3 , VEC4 , INT ,
+		COLOR , COLOR_GRADING , CAMERA
+	};
+
+	E_Type type;
+	std::vector< std::string > inputs;
+	bool enabled;
+};
+using P_SyncUIOverride = std::unique_ptr< T_SyncUIOverride >;
+using T_SyncUIOverrides = std::vector< P_SyncUIOverride >;
+
+// UI override sections
+struct T_SyncUISection;
+using P_SyncUISection = std::unique_ptr< T_SyncUISection >;
+using T_SyncUISections = std::vector< P_SyncUISection >;
+struct T_SyncUISection
+{
+	std::string title;
+	T_SyncUISections subsections;
+	T_SyncUIOverrides overrides;
 };
 
+/*============================================================================*/
+
+// Segment of an input's curve
 struct T_SyncSegment
 {
+	enum E_SegmentType
+	{
+		LINEAR ,
+		RAMP ,
+		SMOOTH ,
+		//HERMITE
+	};
+
 	uint32_t nPoints;
-	E_SyncSegment type;
+	E_SegmentType type;
 	std::vector< float > values;		// nPoints items
 	std::vector< uint32_t > durations;	// nPoints - 1 items
 };
 
+// An input curve
+struct T_SyncCurve
+{
+	std::string name;
+	std::vector< T_SyncSegment > segments;
+};
+
+// Pre-computed data for a curve
+struct T_SyncCurveCache
+{
+	using T_SegRef = std::pair< uint32_t , uint32_t >;
+
+	T_SyncCurve const* variable;
+	std::vector< T_SegRef > segRefs;
+	std::vector< float > segStarts;
+
+	T_SyncCurveCache(
+		__rd__ T_SyncCurve const* const variable ,
+		__rd__ const uint32_t duration ,
+		__rd__ const uint32_t position ) noexcept;
+
+	float valueAt(
+		__rd__ const float position ,
+		__rd__ const float units ) const noexcept;
+};
+using P_SyncCurveCache = std::unique_ptr< T_SyncCurveCache >;
+
+/*============================================================================*/
+
+struct T_SyncManager
+{
+	float uDuration;		// Duration - unit size
+	uint32_t iDuration;		// Duration - total units
+
+	float duration( ) const noexcept
+		{ return uDuration * iDuration; }
+
+	// Sync manager data for an input may include a definition, a curve,
+	// or both. The idea behind supporting "curve only" is that a curve may
+	// have been defined for an input that has been removed temporarily
+	// (e.g. because some include was commented out), in which case we don't
+	// want to waste it.
+	struct T_Data
+	{
+		P_SyncInputDfn definition;
+		P_SyncCurveCache curve;
+		bool overriden;
+	};
+
+	// Data and ID<->index map
+	std::vector< T_Data > data;
+	std::map< std::string , uint32_t > posMap;
+
+	// Current time & values
+	float time;
+	std::vector< float > values;
+
+	// Root of the UI's tree
+	T_SyncUISections uiRoot;
+
+	void makeUI( );
+};
+
+/*============================================================================*/
+
 using T_SyncVariable = std::vector< T_SyncSegment >;
-
-
 struct T_SyncData
 {
 	T_SyncData( );