qtdemux: only transform protected caps once

Commit 7873bede3134b15e5066e8d14e54d1f5054d2063
(https://bugzilla.gnome.org/show_bug.cgi?id=760774) changed the
behaviour of qtdemux to call gst_qtdemux_configure_stream() for
every new moof.

When playing a protected stream, gst_qtdemux_configure_stream()
calls gst_qtdemux_configure_protected_caps(). The
gst_qtdemux_configure_protected_caps() function takes the original
media format, puts this in a field called "original-media-type"
and then changes the caps to "application/x-cenc".

The gst_qtdemux_configure_protected_caps() did not handle the case
of being called multiple times, causing it to incorrectly set the
caps. The second call was causing the caps to be set to:

    application/x-cenc, original-media-type"application/x-cenc"

This commit makes gst_qtdemux_configure_protected_caps() check that
the caps have already been transformed, so that it only gets
changed once.

    https://bugzilla.gnome.org/show_bug.cgi?id=761769

1 files changed, 7 insertions, 5 deletions

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index de5f5d559..a45801105 100644
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -6935,11 +6935,13 @@ gst_qtdemux_configure_protected_caps (GstQTDemux * qtdemux,
   }
 
   s = gst_caps_get_structure (stream->caps, 0);
-  gst_structure_set (s,
-      "original-media-type", G_TYPE_STRING, gst_structure_get_name (s),
-      GST_PROTECTION_SYSTEM_ID_CAPS_FIELD, G_TYPE_STRING, selected_system,
-      NULL);
-  gst_structure_set_name (s, "application/x-cenc");
+  if (!gst_structure_has_name (s, "application/x-cenc")) {
+    gst_structure_set (s,
+        "original-media-type", G_TYPE_STRING, gst_structure_get_name (s),
+        GST_PROTECTION_SYSTEM_ID_CAPS_FIELD, G_TYPE_STRING, selected_system,
+        NULL);
+    gst_structure_set_name (s, "application/x-cenc");
+  }
   return TRUE;
 }