audio: fix unmute-at-end logic

The player tried to disable mute before exiting, so that if mute is
emulated by setting volume to 0 and the volume setting is a
system-global one, we don't leave it at 0. However, the logic doing
this at process exit was flawed, as volume settings are handled by
audio output instances and the audio output that set the mute state
may have been closed earlier. Trying to write reliably working logic
that restores volume at exit only would be tricky, so change the code
to always unmute an audio driver before closing it and restore mute
status if one is opened again later.

command.c

@@ -719,8 +719,6 @@ static int mp_property_volume(m_option_t *prop, int action, void *arg,
         return M_PROPERTY_NOT_IMPLEMENTED;
     }
 
-    mpctx->user_muted = 0;
-
     switch (action) {
     case M_PROPERTY_SET:
         if (!arg)
@@ -757,12 +755,10 @@ static int mp_property_mute(m_option_t *prop, int action, void *arg,
         if (!arg)
             return M_PROPERTY_ERROR;
         mixer_setmute(&mpctx->mixer, *(int *) arg);
-        mpctx->user_muted = mpctx->mixer.muted;
         return M_PROPERTY_OK;
     case M_PROPERTY_STEP_UP:
     case M_PROPERTY_STEP_DOWN:
         mixer_setmute(&mpctx->mixer, !mixer_getmute(&mpctx->mixer));
-        mpctx->user_muted = mpctx->mixer.muted;
         return M_PROPERTY_OK;
     default:
         return m_property_flag_ro(prop, action, arg,

mixer.c

@@ -235,10 +235,32 @@ void mixer_reinit(struct mixer *mixer, struct ao *ao)
     const char *restore_reason = mixer->softvol ? "softvol" :
         mixer->ao->driver->info->short_name;
     if (mixer->restore_volume && !strcmp(mixer->restore_volume,
-                                         restore_reason)) {
+                                         restore_reason))
         mixer_setvolume(mixer, left, right);
-        mixer_setmute(mixer, muted);
-    }
+    mixer_setmute(mixer, muted);
     if (mixer->balance != 0)
         mixer_setbalance(mixer, mixer->balance);
 }
+
+/* Called before uninitializing the audio output. The main purpose is to
+ * turn off mute, in case it's a global/persistent setting which might
+ * otherwise be left enabled even after this player instance exits.
+ */
+void mixer_uninit(struct mixer *mixer)
+{
+    checkvolume(mixer);
+    if (mixer->muted) {
+        /* Current audio output API combines playing the remaining buffered
+         * audio and uninitializing the AO into one operation, even though
+         * ideally unmute would happen between those two steps. We can't do
+         * volume changes after uninitialization, but we don't want the
+         * remaining audio to play at full volume either. Thus this
+         * workaround to drop remaining audio first. */
+        ao_reset(mixer->ao);
+        mixer_setmute(mixer, false);
+        /* We remember mute status and re-enable it if we play more audio
+         * in the same process. */
+        mixer->muted = true;
+    }
+    mixer->ao = NULL;
+}

mixer.h

@@ -39,6 +39,7 @@ typedef struct mixer {
 } mixer_t;
 
 void mixer_reinit(struct mixer *mixer, struct ao *ao);
+void mixer_uninit(struct mixer *mixer);
 void mixer_getvolume(mixer_t *mixer, float *l, float *r);
 void mixer_setvolume(mixer_t *mixer, float l, float r);
 void mixer_incvolume(mixer_t *mixer);

mp_core.h

@@ -188,8 +188,6 @@ typedef struct MPContext {
 
     float begin_skip; ///< start time of the current skip while on edlout mode
 
-    short user_muted; ///< Stores whether user wanted muted mode.
-
     int global_sub_size; // this encompasses all subtitle sources
     int global_sub_pos; // this encompasses all subtitle sources
     int set_of_sub_pos;

mplayer.c

@@ -681,8 +681,10 @@ void uninit_player(struct MPContext *mpctx, unsigned int mask)
     if (mask & INITIALIZED_AO) {
         mpctx->initialized_flags &= ~INITIALIZED_AO;
         current_module = "uninit_ao";
-        if (mpctx->ao)
+        if (mpctx->ao) {
+            mixer_uninit(&mpctx->mixer);
             ao_uninit(mpctx->ao, mpctx->stop_play != AT_END_OF_FILE);
+        }
         mpctx->ao = NULL;
     }
 
@@ -691,8 +693,6 @@ void uninit_player(struct MPContext *mpctx, unsigned int mask)
 
 void exit_player_with_rc(struct MPContext *mpctx, enum exit_reason how, int rc)
 {
-    if (mpctx->user_muted)
-        mixer_setmute(&mpctx->mixer, false);
     uninit_player(mpctx, INITIALIZED_ALL);
 #if defined(__MINGW32__) || defined(__CYGWIN__)
     timeEndPeriod(1);