Hardcode the SDL audio driver (again) to `directsound` under Windows.

Windows defaults to `wassapi`, which is a sensible choice. But WASAPI
only guarantees 32 bit float samples, anything else only works if the
driver or something supports it and YQ2 requires 16 bit samples. That
can be worked around by having SDL recode the audio, but I don't want
such a invasive change right before a release.

Another part of #1132.

CHANGELOG

@@ -1,10 +1,11 @@
 Quake II 8.40 to 8.41:
 - Fix an endless loop in the OpenGL 1.4 renderer crashing the game and
   blocking further progress under some circumstances. (by protocultor)
-- Don't force a platform dependend ,hard coded SDL audio driver, let SDL
+- Don't force a platform dependend, hard coded SDL audio driver, let SDL
   choose the driver instead. This may fix the SDL audio backend on some
   platforms. The driver can still be overridden by setting `s_sdldriver`
-  to something else than `auto`.
+  to something else than `auto`. Under Windows `s_sdldriver` defaults
+  `directsound` because `auto` may choose an incompatible driver.
 
 Quake II 8.30 to 8.40:
 - Implement `g_quick_weap`. If set to 1, both weapprev and weapnext

doc/040_cvarlist.md

@@ -303,7 +303,8 @@ it's `+set busywait 0` (setting the `busywait` cvar) and `-portable`
 * **s_sdldriver**: Can be set to the name of a SDL audio driver. If set
   to `auto`, SDL chooses the driver. If set to anything else the given
   driver is forced, regardless if supported by SDL or the platform or
-  not.
+  not. By default set to `directsound` under Windows and `auto` on all
+  other platforms.
 
 * **s_underwater**: Dampen sounds if submerged. Enabled by default.
 

src/client/sound/sdl.c

@@ -1351,7 +1351,11 @@ SDL_BackendInit(void)
 	int sndfreq = (Cvar_Get("s_khz", "44", CVAR_ARCHIVE))->value;
 	int sndchans = (Cvar_Get("sndchannels", "2", CVAR_ARCHIVE))->value;
 
+#if _WIN32
+	cvar_t *s_sdldriver = (Cvar_Get("s_sdldriver", "directsound", CVAR_ARCHIVE));
+#else
 	cvar_t *s_sdldriver = (Cvar_Get("s_sdldriver", "auto", CVAR_ARCHIVE));
+#endif
 
 	if (strcmp(s_sdldriver->string, "auto") != 0)
 	{
@@ -1512,7 +1516,12 @@ SDL_BackendInit(void)
 	int sndbits = (Cvar_Get("sndbits", "16", CVAR_ARCHIVE))->value;
 	int sndfreq = (Cvar_Get("s_khz", "44", CVAR_ARCHIVE))->value;
 	int sndchans = (Cvar_Get("sndchannels", "2", CVAR_ARCHIVE))->value;
+
+#if _WIN32
+	cvar_t *s_sdldriver = (Cvar_Get("s_sdldriver", "directsound", CVAR_ARCHIVE));
+#else
 	cvar_t *s_sdldriver = (Cvar_Get("s_sdldriver", "auto", CVAR_ARCHIVE));
+#endif
 
 	if (strcmp(s_sdldriver->string, "auto") != 0)
 	{