diff --git a/src/NotesLoaderBMS.cpp b/src/NotesLoaderBMS.cpp
index 2e7c0e4d82..b956d7e616 100644
--- a/src/NotesLoaderBMS.cpp
+++ b/src/NotesLoaderBMS.cpp
@@ -138,31 +138,10 @@ static RString FindLargestInitialSubstring( const RString &string1, const RStrin
 	return string1.substr( 0, i );
 }
 
-static StepsType DetermineStepsType( int iPlayer, const NoteData &nd, const RString &sPath )
+static StepsType DetermineStepsType( int iPlayer, const NoteData &nd, const RString &sPath, const int iNumNonEmptyTracks )
 {
 	ASSERT( NUM_BMS_TRACKS == nd.GetNumTracks() );
 
-	bool bTrackHasNote[NUM_NON_AUTO_KEYSOUND_TRACKS];
-	ZERO( bTrackHasNote );
-
-	int iLastRow = nd.GetLastRow();
-	for( int t=0; t<NUM_NON_AUTO_KEYSOUND_TRACKS; t++ )
-	{
-		for( int r=0; r<=iLastRow; r++ )
-		{
-			if( nd.GetTapNote(t, r).type != TapNote::empty )
-			{
-				bTrackHasNote[t] = true;
-				break;
-			}
-		}
-	}
-
-	int iNumNonEmptyTracks = 0;
-	for( int t=0; t<NUM_NON_AUTO_KEYSOUND_TRACKS; t++ )
-		if( bTrackHasNote[t] )
-			iNumNonEmptyTracks++;
-
 	switch( iPlayer )
 	{
 	case 1:	// "1 player"
@@ -170,6 +149,7 @@ static StepsType DetermineStepsType( int iPlayer, const NoteData &nd, const RStr
 		 * 4 - dance 4-panel
 		 * 5 - pop 5-key
 		 * 6 - dance 6-panel, beat 5-key
+		 * 7 - beat 7-key (scratch unused)
 		 * 8 - beat 7-key
 		 * 9 - popn 9-key */
 		switch( iNumNonEmptyTracks ) 
@@ -405,11 +385,9 @@ static void SetTimeSigAdjustments( const MeasureToTimeSig_t &sigs, Song &out, Me
 
 static void ReadTimeSigs( const NameToData_t &mapNameToData, MeasureToTimeSig_t &out )
 {
-	// some convertors change some measure's time signature before any notes are there
-	// it is required because sometimes the BGA starts before the music and the measure size
-	// is the difference between the start of first bar and the BGA.
-	// something like #00002:1.55. that made all subsequent notes 192th.
-	// here, find the lowest measure for notes, and make this function skip the time signatures before it.
+	/* some songs have BGA starting before the music, so convertors a put weird time signature
+	 * at first measure, something like #00002:1.55. that made all subsequent notes 192th.
+	 * here, find the lowest measure for notes track, and make it skip the time signatures before it. */
 	int iStartMeasureNo = 999;
 	NameToData_t::const_iterator it;
 	for( it = mapNameToData.lower_bound("#00000"); it != mapNameToData.end(); ++it )
@@ -604,7 +582,28 @@ static bool LoadFromBMSFile( const RString &sPath, const NameToData_t &mapNameTo
 		}
 	}
 	
-	out.m_StepsType = DetermineStepsType( iPlayer, ndNotes, sPath );
+	bool bTrackHasNote[NUM_NON_AUTO_KEYSOUND_TRACKS];
+	ZERO( bTrackHasNote );
+	
+	int iLastRow = ndNotes.GetLastRow();
+	for( int t=0; t<NUM_NON_AUTO_KEYSOUND_TRACKS; t++ )
+	{
+		for( int r=0; r<=iLastRow; r++ )
+		{
+			if( ndNotes.GetTapNote(t, r).type != TapNote::empty )
+			{
+				bTrackHasNote[t] = true;
+				break;
+			}
+		}
+	}
+	
+	int iNumNonEmptyTracks = 0;
+	for( int t=0; t<NUM_NON_AUTO_KEYSOUND_TRACKS; t++ )
+		if( bTrackHasNote[t] )
+			iNumNonEmptyTracks++;
+	
+	out.m_StepsType = DetermineStepsType( iPlayer, ndNotes, sPath, iNumNonEmptyTracks );
 	if( out.m_StepsType == StepsType_beat_single5 && GetTagFromMap( mapNameToData, "#title", sData ) )
 	{
 		// Hack: guess at 6-panel.
@@ -692,14 +691,30 @@ static bool LoadFromBMSFile( const RString &sPath, const NameToData_t &mapNameTo
 		iTransformNewToOld[11] = BMS_P2_TURN;
 		break;
 	case StepsType_beat_single7:
-		iTransformNewToOld[0] = BMS_P1_KEY1;
-		iTransformNewToOld[1] = BMS_P1_KEY2;
-		iTransformNewToOld[2] = BMS_P1_KEY3;
-		iTransformNewToOld[3] = BMS_P1_KEY4;
-		iTransformNewToOld[4] = BMS_P1_KEY5;
-		iTransformNewToOld[5] = BMS_P1_KEY6;
-		iTransformNewToOld[6] = BMS_P1_KEY7;
-		iTransformNewToOld[7] = BMS_P1_TURN;
+		if( !bTrackHasNote[BMS_P1_KEY7] && bTrackHasNote[BMS_P1_TURN] )
+		{
+			/* special case for o2mania style charts:
+			 * the turntable is used for first key while the real 7th key is not used. */
+			iTransformNewToOld[0] = BMS_P1_TURN;
+			iTransformNewToOld[1] = BMS_P1_KEY1;
+			iTransformNewToOld[2] = BMS_P1_KEY2;
+			iTransformNewToOld[3] = BMS_P1_KEY3;
+			iTransformNewToOld[4] = BMS_P1_KEY4;
+			iTransformNewToOld[5] = BMS_P1_KEY5;
+			iTransformNewToOld[6] = BMS_P1_KEY6;
+			iTransformNewToOld[7] = BMS_P1_KEY7;
+		}
+		else
+		{
+			iTransformNewToOld[0] = BMS_P1_KEY1;
+			iTransformNewToOld[1] = BMS_P1_KEY2;
+			iTransformNewToOld[2] = BMS_P1_KEY3;
+			iTransformNewToOld[3] = BMS_P1_KEY4;
+			iTransformNewToOld[4] = BMS_P1_KEY5;
+			iTransformNewToOld[5] = BMS_P1_KEY6;
+			iTransformNewToOld[6] = BMS_P1_KEY7;
+			iTransformNewToOld[7] = BMS_P1_TURN;
+		}
 		break;
 	case StepsType_beat_double7:
 		iTransformNewToOld[0] = BMS_P1_KEY1;