protection: add GstProtectionMeta to support protected content

In order to support some types of protected streams (such as those
protected using DASH Common Encryption) some per-buffer information
needs to be passed between elements.

This commit adds a GstMeta type called GstProtectionMeta that allows
protection specific information to be added to a GstBuffer. An example
of its usage is qtdemux providing information to each output sample
that enables a downstream element to decrypt it.

This commit adds a utility function to select a supported protection
system from the installed Decryption elements found in the registry.
The gst_protection_select_system function that takes an array of
identifiers and searches the registry for a element of klass Decryptor that
supports one or more of the supplied identifiers. If multiple elements
are found, the one with the highest rank is selected.

This commit adds a unit test for the gst_protection_select_system
function that adds a fake Decryptor element to the registry and then
checks that it can correctly be selected by the utility function.

This commit adds a unit test for GstProtectionMeta that creates
GstProtectionMeta and adds & removes it from a buffer and performs some
simple reference count checks.

API: gst_buffer_add_protection_meta()
API: gst_buffer_get_protection_meta()
API: gst_protection_select_system()
API: gst_protection_meta_api_get_type()
API: gst_protection_meta_get_info()

https://bugzilla.gnome.org/show_bug.cgi?id=705991

1 files changed, 3 insertions, 0 deletions

diff --git a/gst/gstinfo.c b/gst/gstinfo.c
index 730913281..f21023314 100644
--- a/gst/gstinfo.c
+++ b/gst/gstinfo.c
@@ -176,6 +176,7 @@ GstDebugCategory *_priv_GST_CAT_POLL = NULL;
 GstDebugCategory *GST_CAT_META = NULL;
 GstDebugCategory *GST_CAT_LOCKING = NULL;
 GstDebugCategory *GST_CAT_CONTEXT = NULL;
+GstDebugCategory *_priv_GST_CAT_PROTECTION = NULL;
 
 
 #endif /* !defined(GST_DISABLE_GST_DEBUG) || !defined(GST_REMOVE_DISABLED) */
@@ -390,6 +391,8 @@ _priv_gst_debug_init (void)
   GST_CAT_META = _gst_debug_category_new ("GST_META", 0, "meta");
   GST_CAT_LOCKING = _gst_debug_category_new ("GST_LOCKING", 0, "locking");
   GST_CAT_CONTEXT = _gst_debug_category_new ("GST_CONTEXT", 0, NULL);
+  _priv_GST_CAT_PROTECTION =
+      _gst_debug_category_new ("GST_PROTECTION", 0, "protection");
 
   /* print out the valgrind message if we're in valgrind */
   _priv_gst_in_valgrind ();