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.

1 files changed, 25 insertions, 3 deletions

diff --git a/mixer.c b/mixer.c
index e694253b11..793a6ac58e 100644
--- a/mixer.c
+++ b/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;
+}