aout: remove intricate volume/mute transaction system

Volume and mute states are now independant. There is no need to
update them together in a single transaction.

Furthermore, other processes can change the volume and/or mute state
of VLC playback streams asynchronously. Thus volume-up/volume-down
and mute-toggle are not atomic operations even when protected by the
volume lock. We would need to have toggle and up/down provided by the
to the output plugins. That is probably impossible and overkill.
So accept the small race condition and simplify the code.

include/vlc_aout_intf.h

@@ -36,13 +36,20 @@ VLC_API int aout_VolumeSet( vlc_object_t *, float );
 VLC_API int aout_VolumeUp( vlc_object_t *, int, float * );
 #define aout_VolumeUp(a, b, c) aout_VolumeUp(VLC_OBJECT(a), b, c)
 #define aout_VolumeDown(a, b, c) aout_VolumeUp(a, -(b), c)
-VLC_API int aout_MuteToggle( vlc_object_t * );
-#define aout_MuteToggle(a) aout_MuteToggle(VLC_OBJECT(a))
 VLC_API int aout_MuteSet( vlc_object_t *, bool );
 #define aout_MuteSet(a, b) aout_MuteSet(VLC_OBJECT(a), b)
 VLC_API int aout_MuteGet( vlc_object_t * );
 #define aout_MuteGet(a) aout_MuteGet(VLC_OBJECT(a))
 
+static inline int aout_MuteToggle (vlc_object_t *obj)
+{
+    int val = aout_MuteGet (obj);
+    if (val >= 0)
+        val = aout_MuteSet (obj, !val);
+    return val;
+}
+#define aout_MuteToggle(a) aout_MuteToggle(VLC_OBJECT(a))
+
 VLC_API void aout_EnableFilter( vlc_object_t *, const char *, bool );
 #define aout_EnableFilter( o, n, b ) \
         aout_EnableFilter( VLC_OBJECT(o), n, b )

src/audio_output/intf.c

@@ -60,104 +60,52 @@ static audio_output_t *findAout (vlc_object_t *obj)
 }
 #define findAout(o) findAout(VLC_OBJECT(o))
 
-/** Start a volume change transaction. */
-static void prepareVolume (vlc_object_t *obj, audio_output_t **aoutp,
-                           float *vol, bool *mute)
+#undef aout_VolumeGet
+/**
+ * Gets the volume of the output device (independent of mute).
+ * \return Current audio volume (0 = silent, 1 = nominal),
+ * or a strictly negative value if undefined.
+ */
+float aout_VolumeGet (vlc_object_t *obj)
 {
     audio_output_t *aout = findAout (obj);
+    if (aout == NULL)
+        return -1.f;
 
-    /* FIXME: we need interlocking even if aout does not exist! */
-    *aoutp = aout;
-    if (aout != NULL)
-    {
-        obj = VLC_OBJECT(aout); /* use aout volume if aout exists */
-        aout_lock_volume (aout);
-    }
-    if (vol != NULL)
-        *vol = var_InheritInteger (obj, "volume") / (float)AOUT_VOLUME_DEFAULT;
-    if (mute != NULL)
-        *mute = var_InheritBool (obj, "mute");
+    long l = var_InheritInteger (aout, "volume");
+    vlc_object_release (aout);
+    return l / (float)AOUT_VOLUME_DEFAULT;
 }
 
-/** Commit a volume change transaction. */
-static int commitVolume (vlc_object_t *obj, audio_output_t *aout,
-                         float vol, bool mute)
+#undef aout_VolumeSet
+/**
+ * Sets the volume of the output device.
+ * \note The mute status is not changed.
+ */
+int aout_VolumeSet (vlc_object_t *obj, float vol)
 {
     long volume = lroundf (vol * AOUT_VOLUME_DEFAULT);
-    int ret = 0;
+    int ret = -1;
 
+    audio_output_t *aout = findAout (obj);
     if (aout != NULL)
     {
-        /* apply volume to the pipeline */
         aout_lock (aout);
-        if (aout->mute_set != NULL)
-            ret = aout->mute_set (aout, mute);
-        else
-            ret = -1;
-        if (ret == 0 && aout->volume_set != NULL)
+        if (aout->volume_set != NULL)
             ret = aout->volume_set (aout, vol);
         aout_unlock (aout);
-
-        if (ret == 0)
-        {   /* update aout volume if it maintains its own */
-            var_SetInteger (aout, "volume", volume);
-            var_SetBool (aout, "mute", mute);
-        }
-        aout_unlock_volume (aout);
-
         vlc_object_release (aout);
     }
+
     if (ret == 0)
     {   /* update caller (input manager) volume */
         var_SetInteger (obj, "volume", volume);
-        var_SetBool (obj, "mute", mute);
         if (var_InheritBool (obj, "volume-save"))
             config_PutInt (obj, "volume", volume);
     }
     return ret;
 }
 
-/** Cancel a volume change transaction. */
-static void cancelVolume (vlc_object_t *obj, audio_output_t *aout)
-{
-    (void) obj;
-    if (aout != NULL)
-    {
-        aout_unlock_volume (aout);
-        vlc_object_release (aout);
-    }
-}
-
-#undef aout_VolumeGet
-/**
- * Gets the volume of the output device (independent of mute).
- * \return Current audio volume (0 = silent, 1 = nominal),
- * or a strictly negative value if undefined.
- */
-float aout_VolumeGet (vlc_object_t *obj)
-{
-    audio_output_t *aout;
-    float vol;
-
-    prepareVolume (obj, &aout, &vol, NULL);
-    cancelVolume (obj, aout);
-    return vol;
-}
-
-#undef aout_VolumeSet
-/**
- * Sets the volume of the output device.
- * The mute status is not changed.
- */
-int aout_VolumeSet (vlc_object_t *obj, float vol)
-{
-    audio_output_t *aout;
-    bool mute;
-
-    prepareVolume (obj, &aout, NULL, &mute);
-    return commitVolume (obj, aout, vol, mute);
-}
-
 #undef aout_VolumeUp
 /**
  * Raises the volume.
@@ -166,38 +114,21 @@ int aout_VolumeSet (vlc_object_t *obj, float vol)
  */
 int aout_VolumeUp (vlc_object_t *obj, int value, float *volp)
 {
-    audio_output_t *aout;
-    int ret;
-    float vol;
-    bool mute;
-
     value *= var_InheritInteger (obj, "volume-step");
 
-    prepareVolume (obj, &aout, &vol, &mute);
+    float vol = aout_VolumeGet (obj);
+    if (vol < 0.)
+        return -1;
+
     vol += value / (float)AOUT_VOLUME_DEFAULT;
     if (vol < 0.)
         vol = 0.;
-    if (vol > (AOUT_VOLUME_MAX / AOUT_VOLUME_DEFAULT))
-        vol = AOUT_VOLUME_MAX / AOUT_VOLUME_DEFAULT;
-    ret = commitVolume (obj, aout, vol, mute);
+    if (vol > 2.)
+        vol = 2.;
     if (volp != NULL)
         *volp = vol;
-    return ret;
-}
 
-#undef aout_MuteToggle
-/**
- * Toggles the mute state.
- */
-int aout_MuteToggle (vlc_object_t *obj)
-{
-    audio_output_t *aout;
-    float vol;
-    bool mute;
-
-    prepareVolume (obj, &aout, &vol, &mute);
-    mute = !mute;
-    return commitVolume (obj, aout, vol, mute);
+    return aout_VolumeSet (obj, vol);
 }
 
 #undef aout_MuteGet
@@ -207,11 +138,12 @@ int aout_MuteToggle (vlc_object_t *obj)
  */
 int aout_MuteGet (vlc_object_t *obj)
 {
-    audio_output_t *aout;
-    bool mute;
+    audio_output_t *aout = findAout (obj);
+    if (aout == NULL)
+        return -1.f;
 
-    prepareVolume (obj, &aout, NULL, &mute);
-    cancelVolume (obj, aout);
+    bool mute = var_InheritBool (aout, "mute");
+    vlc_object_release (aout);
     return mute;
 }
 
@@ -221,11 +153,21 @@ int aout_MuteGet (vlc_object_t *obj)
  */
 int aout_MuteSet (vlc_object_t *obj, bool mute)
 {
-    audio_output_t *aout;
-    float vol;
+    int ret = -1;
 
-    prepareVolume (obj, &aout, &vol, NULL);
-    return commitVolume (obj, aout, vol, mute);
+    audio_output_t *aout = findAout (obj);
+    if (aout != NULL)
+    {
+        aout_lock (aout);
+        if (aout->mute_set != NULL)
+            ret = aout->mute_set (aout, mute);
+        aout_unlock (aout);
+        vlc_object_release (aout);
+    }
+
+    if (ret == 0)
+        var_SetBool (obj, "mute", mute);
+    return ret;
 }
 
 

src/audio_output/output.c

@@ -347,6 +347,7 @@ static int aout_SoftVolumeSet (audio_output_t *aout, float volume)
      * formula, be sure to update the aout_VolumeHardInit()-based plugins also.
      */
     owner->volume.amp = volume * volume * volume;
+    aout_VolumeReport (aout, volume);
     return 0;
 }
 
@@ -356,6 +357,7 @@ static int aout_SoftMuteSet (audio_output_t *aout, bool mute)
 
     aout_assert_locked (aout);
     owner->volume.mute = mute;
+    aout_MuteReport (aout, mute);
     return 0;
 }
 

src/libvlccore.sym

@@ -17,7 +17,6 @@ aout_MixerRun
 aout_VolumeGet
 aout_VolumeSet
 aout_VolumeUp
-aout_MuteToggle
 aout_MuteSet
 aout_MuteGet
 aout_VolumeSoftInit