[Spice-devel] [PATCH spice-gtk] gst-audio: Do not update mmtime without real audio channel

[Pavel Grunt]

The fake channel has been introduced to get the audio volume by starting
the gstreamer's audio pipeline and querring its volume info (see commit
aa8d044417bbf60685f59163b874ecb4f157c3c9).

Hovewer starting the pipeline updates the mmtime as a side effect. This
may cause a (big) delay in displaying a video stream.

Because the fake channel is only needed to get the volume info, make
sure to not update the mm-time with it.

Reported-by: Christophe de Dinechin <dinechin at redhat.com>
---
 src/spice-gstaudio.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/spice-gstaudio.c b/src/spice-gstaudio.c
index 014c3a5..715f824 100644
--- a/src/spice-gstaudio.c
+++ b/src/spice-gstaudio.c
@@ -38,6 +38,7 @@ struct stream {
     GstElement              *sink;
     guint                   rate;
     guint                   channels;
+    gboolean                fake; /* fake channel just for getting info about audio (volume) */
 };
 
 struct _SpiceGstaudioPrivate {
@@ -264,6 +265,8 @@ static gboolean update_mmtime_timeout_cb(gpointer data)
     SpiceGstaudioPrivate *p = gstaudio->priv;
     GstQuery *q;
 
+    g_return_val_if_fail(!p->playback.fake, TRUE);
+
     q = gst_query_new_latency();
     if (gst_element_query(p->playback.pipe, q)) {
         gboolean live;
@@ -326,7 +329,7 @@ cleanup:
     if (p->playback.pipe)
         gst_element_set_state(p->playback.pipe, GST_STATE_PLAYING);
 
-    if (p->mmtime_id == 0) {
+    if (!p->playback.fake && p->mmtime_id == 0) {
         update_mmtime_timeout_cb(gstaudio);
         p->mmtime_id = g_timeout_add_seconds(1, update_mmtime_timeout_cb, gstaudio);
     }
@@ -569,7 +572,6 @@ static gboolean spice_gstaudio_get_playback_volume_info_finish(SpiceAudio *audio
     GstElement *e;
     gboolean lmute;
     gdouble vol;
-    gboolean fake_channel = FALSE;
     GTask *task = G_TASK(res);
 
     g_return_val_if_fail(g_task_is_valid(task, audio), FALSE);
@@ -584,9 +586,9 @@ static gboolean spice_gstaudio_get_playback_volume_info_finish(SpiceAudio *audio
 
     if (p->playback.sink == NULL || p->playback.channels == 0) {
         SPICE_DEBUG("PlaybackChannel not created yet, force start");
+        p->playback.fake = TRUE;
         /* In order to get system volume, we start the pipeline */
         playback_start(NULL, SPICE_AUDIO_FMT_S16, 2, 48000, audio);
-        fake_channel = TRUE;
     }
 
     if (GST_IS_BIN(p->playback.sink))
@@ -604,9 +606,10 @@ static gboolean spice_gstaudio_get_playback_volume_info_finish(SpiceAudio *audio
     }
     g_object_unref(e);
 
-    if (fake_channel) {
+    if (p->playback.fake) {
         SPICE_DEBUG("Stop faked PlaybackChannel");
         playback_stop(SPICE_GSTAUDIO(audio));
+        p->playback.fake = FALSE;
     }
 
     if (mute != NULL) {
-- 
2.13.3