discoverer: Don't wait for subtitle streams to preroll

Subtitle streams being parse can cause the pipeline to wait indefinitely
to PREROLL. This makes subtitle streams got to PAUSED even if no data is
available. This should not be a cause for concern as we don't expect to
get much data for subtitle streams other than language tags from the
container.

https://bugzilla.gnome.org/show_bug.cgi?id=632291

diff --git a/gst-libs/gst/pbutils/gstdiscoverer.c b/gst-libs/gst/pbutils/gstdiscoverer.c
index 4a7d72d..58d3e52 100644 (file)
--- a/gst-libs/gst/pbutils/gstdiscoverer.c
+++ b/gst-libs/gst/pbutils/gstdiscoverer.c
@@ -443,6 +443,15 @@ uridecodebin_pad_added_cb (GstElement * uridecodebin, GstPad * pad,
 {
   PrivateStream *ps;
   GstPad *sinkpad = NULL;
+  GstCaps *caps;
+  static GstCaps *subs_caps = NULL;
+
+  if (!subs_caps) {
+    subs_caps = gst_caps_from_string ("text/plain; text/x-pango-markup; "
+        "subpicture/x-pgs; subpicture/x-dvb; application/x-subtitle-unknown; "
+        "application/x-ssa; application/x-ass; subtitle/x-kate; "
+        "video/x-dvd-subpicture; ");
+  }
 
   GST_DEBUG_OBJECT (dc, "pad %s:%s", GST_DEBUG_PAD_NAME (pad));
 
@@ -459,6 +468,16 @@ uridecodebin_pad_added_cb (GstElement * uridecodebin, GstPad * pad,
   g_object_set (ps->sink, "silent", TRUE, NULL);
   g_object_set (ps->queue, "max-size-buffers", 1, "silent", TRUE, NULL);
 
+  caps = gst_pad_get_caps_reffed (pad);
+
+  if (gst_caps_can_intersect (caps, subs_caps)) {
+    /* Subtitle streams are sparse and don't provide any information - don't
+     * wait for data to preroll */
+    g_object_set (ps->sink, "async", FALSE, NULL);
+  }
+
+  gst_caps_unref (caps);
+
   gst_bin_add_many (dc->priv->pipeline, ps->queue, ps->sink, NULL);
 
   if (!gst_element_link_pads_full (ps->queue, "src", ps->sink, "sink",