add option to change SDL audio driver

src/engine/engine.cpp

@@ -4586,6 +4586,15 @@ bool DivEngine::initAudioBackend() {
     }
   }
 
+#ifdef HAVE_SDL2
+  if (audioEngine==DIV_AUDIO_SDL) {
+    String audioDriver=getConfString("sdlAudioDriver","");
+    if (!audioDriver.empty()) {
+      SDL_SetHint("SDL_HINT_AUDIODRIVER",audioDriver.c_str());
+    }
+  }
+#endif
+
   lowQuality=getConfInt("audioQuality",0);
   forceMono=getConfInt("forceMono",0);
   clampSamples=getConfInt("clampSamples",0);

src/gui/gui.cpp

@@ -6329,6 +6329,19 @@ bool FurnaceGUI::init() {
   }
 #endif
 
+  int numDriversA=SDL_GetNumAudioDrivers();
+  if (numDriversA<0) {
+    logW("could not list audio drivers! %s",SDL_GetError());
+  } else {
+    for (int i=0; i<numDriversA; i++) {
+      const char* r=SDL_GetAudioDriver(i);
+      if (r==NULL) continue;
+      if (strcmp(r,"disk")==0) continue;
+      if (strcmp(r,"dummy")==0) continue;
+      availAudioDrivers.push_back(String(r));
+    }
+  }
+
   int numDrivers=SDL_GetNumRenderDrivers();
   if (numDrivers<0) {
     logW("could not list render drivers! %s",SDL_GetError());

src/gui/gui.h

@@ -1304,6 +1304,7 @@ class FurnaceGUI {
   std::deque<String> recentFile;
   std::vector<DivInstrumentType> makeInsTypeList;
   std::vector<String> availRenderDrivers;
+  std::vector<String> availAudioDrivers;
 
   bool quit, warnQuit, willCommit, edit, modified, displayError, displayExporting, vgmExportLoop, zsmExportLoop, vgmExportPatternHints;
   bool vgmExportDirectStream, displayInsTypeList;
@@ -1534,6 +1535,7 @@ class FurnaceGUI {
     String macroRelLabel;
     String emptyLabel;
     String emptyLabel2;
+    String sdlAudioDriver;
     DivConfig initialSys;
 
     Settings():
@@ -1686,7 +1688,8 @@ class FurnaceGUI {
       noteRelLabel("==="),
       macroRelLabel("REL"),
       emptyLabel("..."),
-      emptyLabel2("..") {}
+      emptyLabel2(".."),
+      sdlAudioDriver("") {}
   } settings;
 
   struct Tutorial {

src/gui/settings.cpp

@@ -807,6 +807,25 @@ void FurnaceGUI::drawSettings() {
           }
 #endif
 
+          if (settings.audioEngine==DIV_AUDIO_SDL) {
+            ImGui::Text("Driver");
+            ImGui::SameLine();
+            if (ImGui::BeginCombo("##SDLADriver",settings.sdlAudioDriver.empty()?"Automatic":settings.sdlAudioDriver.c_str())) {
+              if (ImGui::Selectable("Automatic",settings.sdlAudioDriver.empty())) {
+                settings.sdlAudioDriver="";
+              }
+              for (String& i: availAudioDrivers) {
+                if (ImGui::Selectable(i.c_str(),i==settings.sdlAudioDriver)) {
+                  settings.sdlAudioDriver=i;
+                }
+              }
+              ImGui::EndCombo();
+            }
+            if (ImGui::IsItemHovered()) {
+              ImGui::SetTooltip("you may need to restart Furnace for this setting to take effect.");
+            }
+          }
+
           ImGui::Text("Device");
           ImGui::SameLine();
           String audioDevName=settings.audioDevice.empty()?"<System default>":settings.audioDevice;
@@ -1324,6 +1343,9 @@ void FurnaceGUI::drawSettings() {
 #endif
             ImGui::EndCombo();
           }
+          if (ImGui::IsItemHovered()) {
+            ImGui::SetTooltip("you may need to restart Furnace for this setting to take effect.");
+          }
           if (curRenderBackend=="SDL") {
             if (ImGui::BeginCombo("Render driver",settings.renderDriver.empty()?"Automatic":settings.renderDriver.c_str())) {
               if (ImGui::Selectable("Automatic",settings.renderDriver.empty())) {
@@ -1336,6 +1358,9 @@ void FurnaceGUI::drawSettings() {
               }
               ImGui::EndCombo();
             }
+            if (ImGui::IsItemHovered()) {
+              ImGui::SetTooltip("you may need to restart Furnace for this setting to take effect.");
+            }
           }
 
           bool dpiScaleAuto=(settings.dpiScale<0.5f);
@@ -2638,6 +2663,7 @@ void FurnaceGUI::syncSettings() {
   settings.midiOutDevice=e->getConfString("midiOutDevice","");
   settings.c163Name=e->getConfString("c163Name",DIV_C163_DEFAULT_NAME);
   settings.renderDriver=e->getConfString("renderDriver","");
+  settings.sdlAudioDriver=e->getConfString("sdlAudioDriver","");
   settings.audioQuality=e->getConfInt("audioQuality",0);
   settings.audioBufSize=e->getConfInt("audioBufSize",1024);
   settings.audioRate=e->getConfInt("audioRate",44100);
@@ -2986,6 +3012,7 @@ void FurnaceGUI::commitSettings() {
   e->setConf("midiOutDevice",settings.midiOutDevice);
   e->setConf("c163Name",settings.c163Name);
   e->setConf("renderDriver",settings.renderDriver);
+  e->setConf("sdlAudioDriver",settings.sdlAudioDriver);
   e->setConf("audioQuality",settings.audioQuality);
   e->setConf("audioBufSize",settings.audioBufSize);
   e->setConf("audioRate",settings.audioRate);