diff --git a/demo.cc b/demo.cc
index 47c25a3..bad302b 100644
--- a/demo.cc
+++ b/demo.cc
@@ -43,6 +43,19 @@ void T_Demo::makeUI( )
 
 void T_Demo::render( )
 {
+	if ( playing ) {
+		const float time = SDL_GetTicks( ) * 1e-3;
+		if ( playingPrevious ) {
+			const float adv = time - lastFrame;
+			position = std::min( adv + position , sync.duration( ) );
+			if ( position >= sync.duration( ) ) {
+				playing = false;
+			}
+		}
+		lastFrame = time;
+	}
+	playingPrevious = playing;
+
 	raymarcher->render( );
 	dof->render( );
 	bloom->render( );
diff --git a/demo.hh b/demo.hh
index da28df3..e3dec2c 100644
--- a/demo.hh
+++ b/demo.hh
@@ -6,6 +6,7 @@
 #include "combine.hh"
 #include "fxaa.hh"
 #include "profiling.hh"
+#include "sync.hh"
 
 
 struct T_Demo
@@ -40,9 +41,17 @@ struct T_Demo
 	const uint32_t width;
 	const uint32_t height;
 
+	T_SyncData sync;
+	float position = 0;
+	bool playing = false;
+
 	std::unique_ptr< T_Raymarcher > raymarcher;
 	std::unique_ptr< T_DoFPass > dof;
 	std::unique_ptr< T_BloomPass > bloom;
 	std::unique_ptr< T_CombinePass > combine;
 	std::unique_ptr< T_FXAAPass > fxaa;
+
+    private:
+	bool playingPrevious = false;
+	float lastFrame;
 };
diff --git a/main.cc b/main.cc
index 11e35fe..2137092 100644
--- a/main.cc
+++ b/main.cc
@@ -29,7 +29,7 @@ struct T_Main
 	uint32_t stopResize = 0;
 	ImVec2 prevSize;
 
-	bool demoCtrl_ = true;
+	bool demoCtrl_ = false;
 	std::unique_ptr< T_Demo > demo;
 
 	void initDemo( );
@@ -176,10 +176,24 @@ void T_Main::makeUI( )
 	ImGui::Begin( "Tools" );
 
 	ImGui::Checkbox( "Demo controls" ,	&demoCtrl_ );
-	ImGui::Checkbox( "Profiler" ,		&Globals::Profiler( ).uiEnabled( ) );
 	ImGui::Checkbox( "Output debugger" ,	&Globals::ODbg( ).uiEnabled( ) );
+	ImGui::Checkbox( "Profiler" ,		&Globals::Profiler( ).uiEnabled( ) );
 	ImGui::Checkbox( "Shaders" ,		&Globals::Shaders( ).uiEnabled( ) );
 
+	if ( demo ) {
+		ImGui::Separator( );
+		const float duration( demo->sync.duration( ) );
+		if ( ImGui::SliderFloat( "" , &demo->position , 0 , duration , "%.1fs" )
+				&& demo->position > duration ) {
+			demo->position = duration;
+			demo->playing = false;
+		}
+		ImGui::SameLine( );
+		if ( ImGui::Button( demo->playing ? "Stop" : "Play" ) ) {
+			demo->playing = !demo->playing;
+		}
+	}
+
 	ImGui::End( );
 
 	if ( demo && demoCtrl_ ) {
diff --git a/sync.cc b/sync.cc
index 779dbf2..ebabe65 100644
--- a/sync.cc
+++ b/sync.cc
@@ -4,6 +4,9 @@
 
 const T_SyncVariable T_SyncData::MissingVariable_{ };
 
+T_SyncData::T_SyncData( )
+	: T_SyncData( 60 * 60 , 1. / 60 )
+{ }
 
 T_SyncData::T_SyncData(
 		__rd__ const uint32_t duration ,
diff --git a/sync.hh b/sync.hh
index 7286efc..790ff97 100644
--- a/sync.hh
+++ b/sync.hh
@@ -25,11 +25,14 @@ using T_SyncVariable = std::vector< T_SyncSegment >;
 
 struct T_SyncData
 {
-	T_SyncData( ) = delete;
+	T_SyncData( );
 	T_SyncData(
 		__rd__ const uint32_t duration ,
 		__rd__ const float units ) noexcept;
 
+	float duration( ) const noexcept
+		{ return duration_ * units_; }
+
 	void setSyncVariable(
 		__rd__ std::string const& name ,
 		__rw__ T_SyncVariable&& variable ) noexcept;