[GStreamer] Don't track volume in preferences

Added a new bp_supports_stream_volume API that returns whether or not
the playbin element supports GST_TYPE_STREAM_VOLUME. If stream volumes
are supported on the pipeline (which, for example, map to the system
mixer), then don't load/save the volume from Banshee's preferences and
instead only load/set volume on the pipeline itself so the application
volume state is always in sync with the pipeline.

This *should* fix bgo#613725, bgo#612362, and bgo#613726, though there
may be some sort of inconsistency on some distributions as this fix will
only apply for GStreamer 0.10.25 or newer (when the
GST_TYPE_STREAM_VOLUME interface was introduced). If the case is that
stream volume was supported internally on playbin2 before 0.10.25 adds
this interface, there's no real way for us to know whether to trust the
pipeline (system/mixer) volume or our internal software volume state.

3 files changed, 41 insertions, 20 deletions

diff --git a/libbanshee/banshee-player-pipeline.c b/libbanshee/banshee-player-pipeline.c
index 1d877c45d..c95208f90 100644
--- a/libbanshee/banshee-player-pipeline.c
+++ b/libbanshee/banshee-player-pipeline.c
@@ -292,6 +292,15 @@ _bp_pipeline_construct (BansheePlayer *player)
     // source and decoder elements) based on source URI and stream content
     player->playbin = gst_element_factory_make ("playbin2", "playbin");
 
+    player->supports_stream_volume = FALSE;
+#if BANSHEE_CHECK_GST_VERSION(0,10,25)
+    player->supports_stream_volume = gst_element_implements_interface (
+        player->playbin, GST_TYPE_STREAM_VOLUME);
+#endif
+
+    bp_debug ("Stream volume supported: %s",
+        player->supports_stream_volume ? "YES" : "NO");
+
 #ifdef ENABLE_GAPLESS
     // Connect a proxy about-to-finish callback that will generate a next-track-starting callback.
     // This can be removed once playbin2 generates its own next-track signal.
diff --git a/libbanshee/banshee-player-private.h b/libbanshee/banshee-player-private.h
index 66ee2a778..cca6b6387 100644
--- a/libbanshee/banshee-player-private.h
+++ b/libbanshee/banshee-player-private.h
@@ -69,6 +69,9 @@
         (GST_VERSION_MAJOR == (major) && GST_VERSION_MINOR == (minor) && \
             GST_VERSION_MICRO >= (micro)))
 
+#if BANSHEE_CHECK_GST_VERSION(0,10,25)
+#include <gst/interfaces/streamvolume.h>
+#endif
 
 #ifdef WIN32
 #define bp_debug(x) banshee_log_debug ("player", x)
@@ -145,6 +148,7 @@ struct BansheePlayer {
     gboolean buffering;
     gchar *cdda_device;
     gboolean in_gapless_transition;
+    gboolean supports_stream_volume;
     
     // Video State
     BpVideoDisplayContextType video_display_context_type;
diff --git a/libbanshee/banshee-player.c b/libbanshee/banshee-player.c
index 4b3ade58a..406bf9473 100644
--- a/libbanshee/banshee-player.c
+++ b/libbanshee/banshee-player.c
@@ -33,9 +33,6 @@
 #include "banshee-player-cdda.h"
 #include "banshee-player-missing-elements.h"
 #include "banshee-player-replaygain.h"
-#if BANSHEE_CHECK_GST_VERSION(0,10,25)
-#include <gst/interfaces/streamvolume.h>
-#endif
 
 // ---------------------------------------------------------------------------
 // Private Functions
@@ -256,37 +253,48 @@ bp_supports_gapless (BansheePlayer *player)
 #endif //ENABLE_GAPLESS
 }
 
+P_INVOKE gboolean
+bp_supports_stream_volume (BansheePlayer *player)
+{
+    g_return_val_if_fail (IS_BANSHEE_PLAYER (player), FALSE);
+    return player->supports_stream_volume;
+}
+
 P_INVOKE void
 bp_set_volume (BansheePlayer *player, gdouble volume)
 {
     g_return_if_fail (IS_BANSHEE_PLAYER (player));
     g_return_if_fail (GST_IS_ELEMENT (player->playbin));
 
-#if BANSHEE_CHECK_GST_VERSION(0,10,25)
-    if (gst_element_implements_interface (player->playbin, GST_TYPE_STREAM_VOLUME))
-      gst_stream_volume_set_volume (GST_STREAM_VOLUME (player->playbin), GST_STREAM_VOLUME_FORMAT_CUBIC, volume);
-    else
-      g_object_set (player->playbin, "volume", CLAMP (volume, 0.0, 1.0), NULL);
-#else
-    g_object_set (player->playbin, "volume", CLAMP (volume, 0.0, 1.0), NULL);
-#endif
+    if (bp_supports_stream_volume (player)) {
+        #if BANSHEE_CHECK_GST_VERSION(0,10,25)
+        gst_stream_volume_set_volume (GST_STREAM_VOLUME (player->playbin),
+            GST_STREAM_VOLUME_FORMAT_CUBIC, volume);
+        #endif
+    } else {
+        g_object_set (player->playbin, "volume", CLAMP (volume, 0.0, 1.0), NULL);
+    }
+
     _bp_rgvolume_print_volume (player);
 }
 
 P_INVOKE gdouble
 bp_get_volume (BansheePlayer *player)
 {
-	gdouble volume;
+    gdouble volume;
+
     g_return_val_if_fail (IS_BANSHEE_PLAYER (player), 0.0);
     g_return_val_if_fail (GST_IS_ELEMENT (player->playbin), 0.0);
-#if BANSHEE_CHECK_GST_VERSION(0,10,25)
-    if (gst_element_implements_interface (player->playbin, GST_TYPE_STREAM_VOLUME))
-      volume = gst_stream_volume_get_volume (GST_STREAM_VOLUME (player->playbin), GST_STREAM_VOLUME_FORMAT_CUBIC);
-    else
-      g_object_get (player->playbin, "volume", &volume, NULL);
-#else
-    g_object_get (player->playbin, "volume", &volume, NULL);
-#endif
+
+    if (bp_supports_stream_volume (player)) {
+        #if BANSHEE_CHECK_GST_VERSION(0,10,25)
+        volume = gst_stream_volume_get_volume (GST_STREAM_VOLUME (player->playbin),
+            GST_STREAM_VOLUME_FORMAT_CUBIC);
+        #endif
+    } else {
+        g_object_get (player->playbin, "volume", &volume, NULL);
+    }
+
     return volume;
 }