Should work nicely.

Makefile

@@ -11,26 +11,32 @@ LIBS = -lsamplerate $(libsnes)
 ifeq ($(BUILD_RSOUND), 1)
    OBJ += audio/rsound.o
    LIBS += -lrsound
+   DEFINES += -DHAVE_RSOUND
 endif
 ifeq ($(BUILD_OSS), 1)
    OBJ += audio/oss.o
+   DEFINES += -DHAVE_OSS
 endif
 ifeq ($(BUILD_ALSA), 1)
    OBJ += audio/alsa.o
    LIBS += -lasound
+   DEFINES += -DHAVE_ALSA
 endif
 ifeq ($(BUILD_ROAR), 1)
    OBJ += audio/roar.o
    LIBS += -lroar
+   DEFINES += -DHAVE_ROAR
 endif
 ifeq ($(BUILD_AL), 1)
    OBJ += audio/openal.o
    LIBS += -lopenal
+   DEFINES += -DHAVE_AL
 endif
 
 ifeq ($(BUILD_OPENGL), 1)
    OBJ += gfx/gl.o
    LIBS += -lglfw
+   DEFINES += -DHAVE_GL
 endif
 
 ifeq ($(BUILD_CG), 1)

config.h.def

@@ -40,8 +40,8 @@
 ////////////////////////
 
 // Chooses which video and audio subsystem to use. Remember to update config.mk if you change these.
-#define VIDEO_DRIVER VIDEO_GL
+#define VIDEO_DEFAULT_DRIVER VIDEO_GL
-#define AUDIO_DRIVER AUDIO_ALSA
+#define AUDIO_DEFAULT_DRIVER AUDIO_ALSA
 
 
 ////////////////

driver.c

@@ -21,7 +21,7 @@
 #include <stdio.h>
 #include <string.h>
 
-static audio_driver_t audio_drivers[] = {
+static const audio_driver_t *audio_drivers[] = {
 #ifdef HAVE_ALSA
    &audio_alsa,
 #endif
@@ -39,12 +39,39 @@ static audio_driver_t audio_drivers[] = {
 #endif
 };
 
-static video_driver_t video_drivers[] = {
+static const video_driver_t *video_drivers[] = {
 #ifdef HAVE_GL
    &video_gl,
 #endif
 };
 
+static void find_audio_driver(void)
+{
+   for (int i = 0; i < sizeof(audio_drivers) / sizeof(audio_driver_t*); i++)
+   {
+      if (strcasecmp(g_settings.audio.driver, audio_drivers[i]->ident) == 0)
+      {
+         driver.audio = audio_drivers[i];
+         return;
+      }
+   }
+   SSNES_ERR("Couldn't find any audio driver named \"%s\"\n", g_settings.audio.driver);
+   exit(1);
+}
+
+static void find_video_driver(void)
+{
+   for (int i = 0; i < sizeof(video_drivers) / sizeof(video_driver_t*); i++)
+   {
+      if (strcasecmp(g_settings.video.driver, video_drivers[i]->ident) == 0)
+      {
+         driver.video = video_drivers[i];
+         return;
+      }
+   }
+   SSNES_ERR("Couldn't find any video driver named \"%s\"\n", g_settings.video.driver);
+   exit(1);
+}
 
 void init_drivers(void)
 {
@@ -66,6 +93,8 @@ void init_audio(void)
       return;
    }
 
+   find_audio_driver();
+
    driver.audio_data = driver.audio->init(strlen(g_settings.audio.device) ? g_settings.audio.device : NULL, g_settings.audio.out_rate, g_settings.audio.latency);
    if ( driver.audio_data == NULL )
       g_extern.audio_active = false;
@@ -98,6 +127,8 @@ void init_video_input(void)
 {
    int scale;
 
+   find_video_driver();
+
    // We multiply scales with 2 to allow for hi-res games.
 #if 0
 #if VIDEO_FILTER == FILTER_NONE

settings.c

@@ -8,6 +8,46 @@ struct settings g_settings;
 
 static void set_defaults(void)
 {
+   const char *def_video = NULL;
+   const char *def_audio = NULL;
+
+   switch (VIDEO_DEFAULT_DRIVER)
+   {
+      case VIDEO_GL:
+         def_video = "glfw";
+         break;
+      default:
+         break;
+   }
+
+   switch (AUDIO_DEFAULT_DRIVER)
+   {
+      case AUDIO_RSOUND:
+         def_audio = "rsound";
+         break;
+      case AUDIO_OSS:
+         def_audio = "oss";
+         break;
+      case AUDIO_ALSA:
+         def_audio = "alsa";
+         break;
+      case AUDIO_ROAR:
+         def_audio = "roar";
+         break;
+      case AUDIO_AL:
+         def_audio = "openal";
+         break;
+      default:
+         break;
+   }
+
+   // No input atm ... It is in the GLFW driver.
+
+   if (def_video)
+      strncpy(g_settings.video.driver, def_video, sizeof(g_settings.video.driver) - 1);
+   if (def_audio)
+      strncpy(g_settings.audio.driver, def_audio, sizeof(g_settings.audio.driver) - 1);
+
    g_settings.video.xscale = xscale;
    g_settings.video.yscale = yscale;
    g_settings.video.fullscreen = fullscreen;
@@ -140,6 +180,17 @@ void parse_config(void)
          g_settings.audio.src_quality = quals[tmp_int];
    }
 
+   if (config_get_string(conf, "video_driver", &tmp_str))
+   {
+      strncpy(g_settings.video.driver, tmp_str, sizeof(g_settings.video.driver) - 1);
+      free(tmp_str);
+   }
+   if (config_get_string(conf, "audio_driver", &tmp_str))
+   {
+      strncpy(g_settings.audio.driver, tmp_str, sizeof(g_settings.audio.driver) - 1);
+      free(tmp_str);
+   }
+
    // TODO: Keybinds.
 
    config_file_free(conf);