gst-player: support setting the video sink from environment var

Also initialize the video sink to 'glimagesink' in case it has not been
configured from the environment, but only for the X11 application
(gtk-play). This recipe also provides a command line application for
framebuffer (gst-play) that is not affected by this change.

https://jira.digi.com/browse/DEL-2132

Signed-off-by: Javier Viguera <javier.viguera@digi.com>

meta-digi-dey/recipes-multimedia/gstreamer/gst-player/0001-gstplayer-force-use-glimagesink.patch

@@ -0,0 +1,52 @@
+From: Javier Viguera <javier.viguera@digi.com>
+Date: Fri, 15 Jan 2016 17:21:01 +0100
+Subject: [PATCH] gstplayer: force use glimagesink
+
+Add support to set the video sink from an environment variable. For the
+X11 application (gtk-play) use the 'glimagesink' video sink if it has not
+been set in the environment.
+
+Signed-off-by: Javier Viguera <javier.viguera@digi.com>
+---
+ gtk/gtk-play.c             | 3 +++
+ lib/gst/player/gstplayer.c | 6 ++++++
+ 2 files changed, 9 insertions(+)
+
+diff --git a/gtk/gtk-play.c b/gtk/gtk-play.c
+index b92773b115b5..a364ffcb349d 100644
+--- a/gtk/gtk-play.c
++++ b/gtk/gtk-play.c
+@@ -403,6 +403,9 @@ main (gint argc, gchar ** argv)
+     file_names = NULL;
+   }
+ 
++  /* Use 'glimagesink' for gtk-play if not already configured in the environment */
++  g_setenv("VIDEOSINK", "glimagesink", FALSE);
++
+   play.player = gst_player_new ();
+   play.playing = TRUE;
+ 
+diff --git a/lib/gst/player/gstplayer.c b/lib/gst/player/gstplayer.c
+index bd682d97b4b8..0c4869a9aa53 100644
+--- a/lib/gst/player/gstplayer.c
++++ b/lib/gst/player/gstplayer.c
+@@ -1033,6 +1033,7 @@ request_state_cb (GstBus * bus, GstMessage * msg, gpointer user_data)
+ static gpointer
+ gst_player_main (gpointer data)
+ {
++  GstElement *videosink;
+   GstPlayer *self = GST_PLAYER (data);
+   GstBus *bus;
+   GSource *source;
+@@ -1053,6 +1054,11 @@ gst_player_main (gpointer data)
+ 
+   self->priv->playbin = gst_element_factory_make ("playbin", "playbin");
+ 
++  /* Use video sink from environment variable */
++  videosink = gst_element_factory_make(g_getenv("VIDEOSINK"), NULL);
++  if (videosink)
++      g_object_set(self->priv->playbin, "video-sink", videosink, NULL);
++
+   self->priv->bus = bus = gst_element_get_bus (self->priv->playbin);
+   bus_source = gst_bus_create_watch (bus);
+   g_source_set_callback (bus_source, (GSourceFunc) gst_bus_async_signal_func,

meta-digi-dey/recipes-multimedia/gstreamer/gst-player_git.bbappend

@@ -0,0 +1,5 @@
+# Copyright (C) 2016 Digi International
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/${BPN}:"
+
+SRC_URI_append = " file://0001-gstplayer-force-use-glimagesink.patch"