video/games/sdl3-doom/patches/0004-i_sound-share-a-single-SDL3_mixer-device-between-mus.patch

From 586e123b3d64025739c6eef8e3f16c1091166150 Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Tue, 9 Jun 2026 17:06:08 +0100
Subject: [PATCH] i_sound: share a single SDL3_mixer device between music and
 SFX

The SDL2_mixer build opened one audio device with Mix_OpenAudio() that
was shared by music and every sound effect channel. The port to the
SDL3_mixer 3.2 MIX_* API instead created two independent mixers, one in
i_sdlmusic.c (music_mixer) and one in i_sdlsound.c (sound_mixer), each
via its own MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK).
That opens two separate output streams on the default device and leaves
both backends independently calling SDL_Init(SDL_INIT_AUDIO), MIX_Init()
and, on shutdown, MIX_Quit() plus SDL_QuitSubSystem(); whichever backend
shuts down first tears the mixer library out from under the other.

Introduce a small reference-counted helper, i_sdlmixer, that owns one
MIX_Mixer on the default playback device. Both backends acquire it on
init and release it on shutdown, so the device, MIX_Init() and the audio
subsystem are set up once and torn down once. Each backend keeps its own
MIX_Track(s) on the shared mixer, which matches the canonical SDL3_mixer
model of one mixer feeding many tracks.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 CMakeLists.txt       |  4 +-
 include/i_sdlmixer.h | 29 +++++++++++++++
 src/i_sdlmixer.c     | 87 ++++++++++++++++++++++++++++++++++++++++++++
 src/i_sdlmusic.c     | 65 +++++++--------------------------
 src/i_sdlsound.c     | 28 +++-----------
 5 files changed, 138 insertions(+), 75 deletions(-)
 create mode 100644 include/i_sdlmixer.h
 create mode 100644 src/i_sdlmixer.c

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,8 +12,8 @@ include_directories(${SDL3_MIXER_INCLUDE
 add_definitions(-Wall -D_REENTRANT -D_THREAD_SAFE)
 add_executable(sdl3-doom src/i_main.c src/dummy.c src/am_map.c src/doomdef.c src/doomstat.c src/dstrings.c src/d_event.c
  src/d_items.c src/d_iwad.c src/d_loop.c src/d_main.c src/d_mode.c src/d_net.c src/f_finale.c src/f_wipe.c src/g_game.c src/hu_lib.c 
- src/hu_stuff.c src/info.c src/i_cdmus.c src/i_endoom.c src/i_joystick.c src/i_scale.c src/i_sound.c src/i_sdlmusic.c  
- src/i_sdlsound.c src/i_system.c src/i_timer.c src/i_input.c  src/i_video.c  src/mus2mid.c  src/memio.c src/m_argv.c 
+ src/hu_stuff.c src/info.c src/i_cdmus.c src/i_endoom.c src/i_joystick.c src/i_scale.c src/i_sound.c src/i_sdlmixer.c src/i_sdlmusic.c
+ src/i_sdlsound.c src/i_system.c src/i_timer.c src/i_input.c  src/i_video.c  src/mus2mid.c  src/memio.c src/m_argv.c
  src/m_bbox.c src/m_cheat.c src/m_config.c src/m_controls.c src/m_fixed.c src/m_menu.c src/m_misc.c src/m_random.c 
  src/p_ceilng.c src/p_doors.c src/p_enemy.c src/p_floor.c src/p_inter.c src/p_lights.c src/p_map.c src/p_maputl.c 
  src/p_mobj.c src/p_plats.c src/p_pspr.c src/p_saveg.c src/p_setup.c src/p_sight.c src/p_spec.c src/p_switch.c 
--- /dev/null
+++ b/include/i_sdlmixer.h
@@ -0,0 +1,29 @@
+//
+// Copyright(C) 1993-1996 Id Software, Inc.
+// Copyright(C) 2005-2014 Simon Howard
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// DESCRIPTION:
+//	Shared SDL3_mixer device, used by both the music and sound
+//	effect backends.
+//
+
+#ifndef __I_SDLMIXER__
+#define __I_SDLMIXER__
+
+#include "SDL3_mixer/SDL_mixer.h"
+#include "doomtype.h"
+
+MIX_Mixer *I_SDLMixer_Acquire(void);
+void I_SDLMixer_Release(void);
+
+#endif
--- /dev/null
+++ b/src/i_sdlmixer.c
@@ -0,0 +1,87 @@
+//
+// Copyright(C) 1993-1996 Id Software, Inc.
+// Copyright(C) 2005-2014 Simon Howard
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// DESCRIPTION:
+//	Shared SDL3_mixer device, used by both the music and sound
+//	effect backends.
+//
+
+#include <stdio.h>
+
+#include "SDL3/SDL.h"
+#include "SDL3_mixer/SDL_mixer.h"
+
+#include "i_sdlmixer.h"
+#include "i_sound.h"
+
+static MIX_Mixer *shared_mixer = NULL;
+static int mixer_refcount = 0;
+
+MIX_Mixer *I_SDLMixer_Acquire(void)
+{
+    if (shared_mixer != NULL)
+    {
+        ++mixer_refcount;
+        return shared_mixer;
+    }
+
+    if (!SDL_Init(SDL_INIT_AUDIO))
+    {
+        fprintf(stderr, "Unable to set up sound.\n");
+        return NULL;
+    }
+
+    if (!MIX_Init())
+    {
+        fprintf(stderr, "Error initialising SDL3_mixer: %s\n", SDL_GetError());
+        SDL_QuitSubSystem(SDL_INIT_AUDIO);
+        return NULL;
+    }
+
+    const SDL_AudioSpec spec = {SDL_AUDIO_S16, 2, snd_samplerate};
+
+    shared_mixer = MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec);
+
+    if (shared_mixer == NULL)
+    {
+        fprintf(stderr, "Error initialising SDL3_mixer: %s\n", SDL_GetError());
+        MIX_Quit();
+        SDL_QuitSubSystem(SDL_INIT_AUDIO);
+        return NULL;
+    }
+
+    mixer_refcount = 1;
+
+    return shared_mixer;
+}
+
+void I_SDLMixer_Release(void)
+{
+    if (mixer_refcount <= 0)
+    {
+        return;
+    }
+
+    --mixer_refcount;
+
+    if (mixer_refcount > 0)
+    {
+        return;
+    }
+
+    MIX_DestroyMixer(shared_mixer);
+    shared_mixer = NULL;
+    MIX_Quit();
+    SDL_QuitSubSystem(SDL_INIT_AUDIO);
+}
--- a/src/i_sdlmusic.c
+++ b/src/i_sdlmusic.c
@@ -31,6 +31,7 @@
 
 #include "deh_str.h"
 #include "gusconf.h"
+#include "i_sdlmixer.h"
 #include "i_sound.h"
 #include "i_system.h"
 #include "i_swap.h"
@@ -102,11 +103,6 @@ static const char *subst_config_filename
 
 static boolean music_initialized = false;
 
-// If this is true, this module initialized SDL sound and has the 
-// responsibility to shut it down
-
-static boolean sdl_was_initialized = false;
-
 static boolean musicpaused = false;
 static int current_music_volume;
 
@@ -856,24 +852,13 @@ static void I_SDL_ShutdownMusic(void)
         MIX_StopTrack(music_track, 0);
         music_initialized = false;
 
-        if (sdl_was_initialized)
-        {
-            MIX_DestroyTrack(music_track);
-            music_track = NULL;
-            MIX_DestroyMixer(music_mixer);
-            music_mixer = NULL;
-            MIX_Quit();
-            SDL_QuitSubSystem(SDL_INIT_AUDIO);
-            sdl_was_initialized = false;
-        }
+        MIX_DestroyTrack(music_track);
+        music_track = NULL;
+        music_mixer = NULL;
+        I_SDLMixer_Release();
     }
 }
 
-static boolean SDLIsInitialized(void)
-{
-    return music_mixer != NULL;
-}
-
 // Initialize music subsystem
 static boolean I_SDL_InitMusic(void)
 {
@@ -914,42 +899,20 @@ static boolean I_SDL_InitMusic(void)
         DumpSubstituteConfig(myargv[i + 1]);
     }
 
-    // If SDL_mixer is not initialized, we have to initialize it
-    // and have the responsibility to shut it down later on.
+    music_mixer = I_SDLMixer_Acquire();
 
-    if (SDLIsInitialized())
-    {
-        music_initialized = true;
-    }
-    else
+    if (music_mixer != NULL)
     {
-        const SDL_AudioSpec spec = {SDL_AUDIO_S16, 2, 44100};
-        if (!SDL_Init(SDL_INIT_AUDIO))
-        {
-            fprintf(stderr, "Unable to set up sound.\n");
-        }
-        else if (!MIX_Init())
-        {
-            fprintf(stderr, "Error initializing SDL3_mixer: %s\n",
-                    SDL_GetError());
-            SDL_QuitSubSystem(SDL_INIT_AUDIO);
-        }
-        else if (!(music_mixer = MIX_CreateMixerDevice(
-                       SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec)))
-        {
-            fprintf(stderr, "Error initializing SDL3_mixer: %s\n",
-                    SDL_GetError());
-            MIX_Quit();
-            SDL_QuitSubSystem(SDL_INIT_AUDIO);
-        }
-        else
+        SDL_AudioSpec spec;
+
+        music_track = MIX_CreateTrack(music_mixer);
+
+        if (MIX_GetMixerFormat(music_mixer, &spec))
         {
-            music_track = MIX_CreateTrack(music_mixer);
             music_freq = spec.freq;
-
-            sdl_was_initialized = true;
-            music_initialized = true;
         }
+
+        music_initialized = true;
     }
 
     // Once initialization is complete, the temporary Timidity config
--- a/src/i_sdlsound.c
+++ b/src/i_sdlsound.c
@@ -32,6 +32,7 @@
 #endif
 
 #include "deh_str.h"
+#include "i_sdlmixer.h"
 #include "i_sound.h"
 #include "i_system.h"
 #include "i_swap.h"
@@ -957,10 +958,8 @@ static void I_SDL_ShutdownSound(void)
         sound_tracks[i] = NULL;
     }
 
-    MIX_DestroyMixer(sound_mixer);
     sound_mixer = NULL;
-    MIX_Quit();
-    SDL_QuitSubSystem(SDL_INIT_AUDIO);
+    I_SDLMixer_Release();
 
     sound_initialized = false;
 }
@@ -978,33 +977,18 @@ static boolean I_SDL_InitSound(boolean _
         channels_playing[i] = NULL;
     }
 
-    if (!SDL_Init(SDL_INIT_AUDIO))
-    {
-        fprintf(stderr, "Unable to set up sound.\n");
-        return false;
-    }
-    const SDL_AudioSpec spec = {SDL_AUDIO_S16, 2, snd_samplerate};
-
-    if (!MIX_Init())
-    {
-        fprintf(stderr, "Error initialising SDL3_mixer: %s\n", SDL_GetError());
-        return false;
-    }
-
-    sound_mixer = MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec);
+    sound_mixer = I_SDLMixer_Acquire();
 
     if (sound_mixer == NULL)
     {
-        fprintf(stderr, "Error initialising SDL3_mixer: %s\n", SDL_GetError());
-        MIX_Quit();
         return false;
     }
 
     ExpandSoundData = ExpandSoundData_SDL;
 
-    mixer_freq = spec.freq;
-    mixer_format = spec.format;
-    mixer_channels = spec.channels;
+    mixer_freq = snd_samplerate;
+    mixer_format = SDL_AUDIO_S16;
+    mixer_channels = 2;
 
 #ifdef HAVE_LIBSAMPLERATE
     if (use_libsamplerate != 0)