questshock/android/engine-patches/16-android-audio-single-device.patch

--- a/src/MacSrc/SDLSound.c
+++ b/src/MacSrc/SDLSound.c
@@ -19,24 +19,6 @@
 
     // Startup the sound system
 
-    SDL_AudioSpec spec, obtained;
-    spec.freq = 48000;
-    spec.format = AUDIO_S16SYS;
-    spec.channels = 2;
-    spec.samples = 2048;
-    spec.callback = AudioStreamCallback;
-    spec.userdata = (void *)&cutscene_audiostream;
-
-    extern SDL_AudioDeviceID device;
-    device = SDL_OpenAudioDevice(NULL, 0, &spec, &obtained, 0);
-
-    if (device == 0) {
-        ERROR("Could not open SDL audio: %s", SDL_GetError());
-    } else {
-        INFO("Opened Music Stream, deviceID %d, freq %d, size %d, format %d, channels %d, samples %d", device,
-             obtained.freq, obtained.size, obtained.format, obtained.channels, obtained.samples);
-    }
-
     if (Mix_Init(MIX_INIT_MP3) < 0) {
         ERROR("%s: Init failed", __FUNCTION__);
     }
@@ -50,10 +32,18 @@
     Mix_HookMusic(MusicCallback, (void *)&MusicDev);
     Mix_VolumeMusic(MIX_MAX_VOLUME); // use max volume for music stream
 
+    // Cutscene/audiolog playback (AudioStreamCallback, see cutsloop.c) used to
+    // run through its own SDL_OpenAudioDevice() device, separate from this
+    // one - SDL only ever allows one open non-capture device on Android's
+    // audio backends, so that second open always failed with "Audio device
+    // already open" and both SFX and MIDI music (both routed through this
+    // Mix_OpenAudio device) silently never played. Mixed into this device's
+    // post-mix stage instead, so there is only ever one device open.
+    Mix_SetPostMix(AudioStreamCallback, (void *)&cutscene_audiostream);
+
     InitReadXMI();
 
     atexit(Mix_CloseAudio);
-    atexit(SDL_CloseAudio);
 
     return OK;
 }
--- a/src/MacSrc/Shock.c
+++ b/src/MacSrc/Shock.c
@@ -60,8 +60,6 @@
 SDL_Palette *sdlPalette;
 SDL_Renderer *renderer;
 
-SDL_AudioDeviceID device;
-
 int num_args;
 char **arg_values;
 
--- a/src/GameSrc/cutsloop.c
+++ b/src/GameSrc/cutsloop.c
@@ -83,15 +83,25 @@
 extern char FrnSubtitle[256];
 extern char GerSubtitle[256];
 
-extern SDL_AudioDeviceID device;
-
-
+// Runs as SDL_mixer's post-mix hook (see snd_start_digital() in
+// SDLSound.c) rather than a dedicated SDL audio device's callback, so
+// SFX/MIDI music sharing the same device are already mixed into `stream`
+// by the time this runs - mix in rather than overwrite, so they aren't
+// silenced whenever a cutscene or audiolog is playing.
 void AudioStreamCallback(void *userdata, unsigned char *stream, int len)
 {
+  static Uint8 mixbuf[MOVIE_DEFAULT_BLOCKLEN * 4];
   SDL_AudioStream *as = *(SDL_AudioStream **)userdata;
 
-  if (as != NULL && SDL_AudioStreamAvailable(as) > 0)
-    SDL_AudioStreamGet(as, stream, len);
+  if (as == NULL || SDL_AudioStreamAvailable(as) <= 0)
+    return;
+
+  if (len > (int)sizeof(mixbuf))
+    len = (int)sizeof(mixbuf);
+
+  int got = SDL_AudioStreamGet(as, mixbuf, len);
+  if (got > 0)
+    SDL_MixAudioFormat(stream, mixbuf, AUDIO_S16SYS, got, SDL_MIX_MAXVOLUME);
 }
 
 
@@ -153,11 +163,13 @@
 
   if (cutscene_audiostream != NULL)
   {
-    SDL_PauseAudioDevice(device, 1);
-    SDL_Delay(1);
-
+    // AudioStreamCallback (SDL_mixer's post-mix hook) runs continuously on
+    // SDL_mixer's own audio thread and reads this pointer - lock around
+    // freeing it so that thread can't be mid-read when it's freed.
+    SDL_LockAudio();
     SDL_FreeAudioStream(cutscene_audiostream);
     cutscene_audiostream = NULL;
+    SDL_UnlockAudio();
 
     if (cutscene_audiobuffer)
     {
@@ -184,8 +196,6 @@
 
   if (cutscene_audiostream)
   {
-    SDL_PauseAudioDevice(device, 0);
-  
     if (cutscene_audiobuffer_size > 0)
     {
       // === adjust volume in buffer here ===
@@ -325,10 +335,9 @@
 
   if (sfx_on)
   {
-    SDL_PauseAudioDevice(device, 1);
-    SDL_Delay(1);
-
+    SDL_LockAudio();
     cutscene_audiostream = SDL_NewAudioStream(AUDIO_U8, 1, fix_int(amovie->a.sampleRate), AUDIO_S16SYS, 2, 48000);
+    SDL_UnlockAudio();
 
     cutscene_audiobuffer_pos = cutscene_audiobuffer;
   }
--- a/src/GameSrc/audiolog.c
+++ b/src/GameSrc/audiolog.c
@@ -61,8 +61,6 @@
 extern uchar curr_alog_vol;
 extern char which_lang;
 
-extern SDL_AudioDeviceID device;
-
 errtype audiolog_init(void) { return OK; }
 
 errtype audiolog_play(int email_id) {
@@ -114,10 +112,9 @@
 
     DEBUG("%s: Playing email", __FUNCTION__);
 
-    SDL_PauseAudioDevice(device, 1);
-    SDL_Delay(1);
-
+    SDL_LockAudio();
     cutscene_audiostream = SDL_NewAudioStream(AUDIO_U8, 1, fix_int(palog->a.sampleRate), AUDIO_S16SYS, 2, 48000);
+    SDL_UnlockAudio();
 
     audiolog_audiobuffer_pos = audiolog_audiobuffer;
 
@@ -150,11 +147,14 @@
     }
 
     if (cutscene_audiostream != NULL) {
-        SDL_PauseAudioDevice(device, 1);
-        SDL_Delay(1);
-
+        // AudioStreamCallback (SDL_mixer's post-mix hook, see cutsloop.c)
+        // runs continuously on SDL_mixer's own audio thread and reads this
+        // pointer - lock around freeing it so that thread can't be
+        // mid-read when it's freed.
+        SDL_LockAudio();
         SDL_FreeAudioStream(cutscene_audiostream);
         cutscene_audiostream = NULL;
+        SDL_UnlockAudio();
 
         if (audiolog_audiobuffer) {
             free(audiolog_audiobuffer);
@@ -177,8 +177,6 @@
 
 errtype audiolog_loop_callback(void) {
     if (cutscene_audiostream) {
-        SDL_PauseAudioDevice(device, 0);
-
         if (audiolog_audiobuffer_size > 0) {
             int i, vol = curr_alog_vol * 127 / 100; // convert from 0-100 to 0-127