- added a CVAR to disable WT's ogg music and a fallback for when it cannot be found.

Fixes #354

source/common/audio/music/music.cpp

@@ -319,7 +319,7 @@ bool S_ChangeMusic(const char* musicname, int order, bool looping, bool force)
 
 	if (!force && PlayList.GetNumSongs())
 	{ // Don't change if a playlist is active
-		return false;
+		return true; // do not report an error here.
 	}
 	// Do game specific lookup.
 	FString musicname_;

source/core/raze_music.cpp

@@ -197,7 +197,7 @@ int Mus_Play(const char *mapname, const char *fn, bool loop)
 	
 	if (!MusicEnabled())
 	{
-		return 0;
+		return 1;
 	}
 
 	// Allow per level music substitution.

source/games/duke/src/sounds.cpp

@@ -587,12 +587,44 @@ void S_MenuSound(void)
 //
 //==========================================================================
 
+CVAR(Bool, wt_forcemidi, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG) // quick hack to disable the oggs, which are of lower quality than playing the MIDIs with a good synth and sound font.
+
 static bool cd_disabled = false;    // This is in case mus_redbook is enabled but no tracks found so that the regular music system can be switched on.
 
+static void MusPlay(const char* label, const char* music, bool loop)
+{
+	if (isWorldTour())
+	{
+		if (wt_forcemidi)
+		{
+			FString alternative = music;
+			alternative.Substitute(".ogg", ".mid");
+			int num = fileSystem.FindFile(alternative);
+			if (num >= 0)
+			{
+				int file = fileSystem.GetFileContainer(num);
+				if (file == 1)
+				{
+					Mus_Play(label, alternative, loop);
+					return;
+				}
+			}
+		}
+	}
+	int result = Mus_Play(label, music, loop);
+	// do not remain silent if playing World Tour when the user has deleted the music.
+	if (!result && isWorldTour())
+	{
+		FString alternative = music;
+		alternative.Substitute(".ogg", ".mid");
+		Mus_Play(label, alternative, loop);
+	}
+}
+
 void S_PlayLevelMusic(MapRecord *mi)
 {
 	if (isRR() && mi->music.IsEmpty() && mus_redbook && !cd_disabled) return;
-	Mus_Play(mi->labelName, mi->music, true);
+	MusPlay(mi->labelName, mi->music, true);
 }
 
 void S_PlaySpecialMusic(unsigned int m)
@@ -601,7 +633,7 @@ void S_PlaySpecialMusic(unsigned int m)
 	auto& musicfn = specialmusic[m];
 	if (musicfn.IsNotEmpty())
 	{
-		Mus_Play(nullptr, musicfn, true);
+		MusPlay(nullptr, musicfn, true);
 	}
 }