From a816d8dab6bb33770150289a4aede43e2f7ae478 Mon Sep 17 00:00:00 2001
From: Charlie Turner <chturne@gmail.com>
Date: Fri, 10 May 2019 23:34:43 +0200
Subject: [PATCH] Check if an upstream demuxer provided a default kid.

Smooth streaming demuxers do not send boxes containing metadata about
the stream. They have to send metadata "out-of-band".

For piff encoded streams, if no box has been found containing a default
kid for the sample, check if an upstream demuxer has provided one via a
protection event, and use this as a fallback.

Signed-off-by: Xabier Rodriguez Calvar <calvaris@igalia.com>
---
 gst/isomp4/qtdemux.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index cf15fad46..e449b480c 100644
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -451,6 +451,7 @@ struct _QtDemuxStream
   guint32 protection_scheme_version;
   gpointer protection_scheme_info;      /* specific to the protection scheme */
   GQueue protection_scheme_event_queue;
+  GstBuffer *default_kid;
 
   gint ref_count;               /* atomic */
 };
@@ -2008,6 +2009,7 @@ _create_stream (GstQTDemux * demux, guint32 track_id)
   stream->stream_tags = gst_tag_list_new_empty ();
   gst_tag_list_set_scope (stream->stream_tags, GST_TAG_SCOPE_STREAM);
   g_queue_init (&stream->protection_scheme_event_queue);
+  stream->default_kid = NULL;
   stream->ref_count = 1;
   /* consistent default for push based mode */
   gst_segment_init (&stream->segment, GST_FORMAT_TIME);
@@ -2476,6 +2478,32 @@ gst_qtdemux_handle_sink_event (GstPad * sinkpad, GstObject * parent,
     case GST_EVENT_PROTECTION:
     {
       const gchar *system_id = NULL;
+      GstBuffer *default_key_id = NULL;
+      const GstStructure *structure;
+      QtDemuxStream *stream = NULL;
+      GstMapInfo map;
+
+      structure = gst_event_get_structure (event);
+      if (gst_structure_has_field_typed (structure, "key_id", GST_TYPE_BUFFER)) {
+        gst_structure_get (structure, "key_id", GST_TYPE_BUFFER,
+            &default_key_id, NULL);
+        GST_DEBUG_OBJECT (demux,
+            "received a default key id of size %" G_GSIZE_FORMAT,
+            gst_buffer_get_size (default_key_id));
+
+        if (gst_debug_category_get_threshold (GST_CAT_DEFAULT) >=
+            GST_LEVEL_MEMDUMP) {
+          gst_buffer_map (default_key_id, &map, GST_MAP_READ);
+          GST_MEMDUMP_OBJECT (demux, "default key id", (guint8 *) map.data,
+              map.size);
+          gst_buffer_unmap (default_key_id, &map);
+        }
+
+        if (QTDEMUX_N_STREAMS (demux)) {
+          stream = QTDEMUX_NTH_STREAM (demux, 0);
+          stream->default_kid = default_key_id;
+        }
+      }
 
       gst_event_parse_protection (event, &system_id, NULL, NULL);
       GST_DEBUG_OBJECT (demux, "Received protection event for system ID %s",
@@ -2688,6 +2716,8 @@ gst_qtdemux_stream_clear (QtDemuxStream * stream)
   g_queue_foreach (&stream->protection_scheme_event_queue,
       (GFunc) gst_event_unref, NULL);
   g_queue_clear (&stream->protection_scheme_event_queue);
+  if (stream->default_kid)
+    gst_buffer_unref (stream->default_kid);
   gst_qtdemux_stream_flush_segments_data (stream);
   gst_qtdemux_stream_flush_samples_data (stream);
 }
@@ -2954,6 +2984,19 @@ qtdemux_parse_piff (GstQTDemux * qtdemux, const guint8 * buffer, gint length,
     uses_sub_sample_encryption = TRUE;
   }
 
+  // In the case of smooth streaming, we never get moov boxes and their
+  // default encryption metadata. Instead, the demuxer has to parse this
+  // information out of the playready specific payloads and make it availble
+  // somehow to us.
+  if (!gst_structure_has_field (ss_info->default_properties, "kid")) {
+    if (!stream->default_kid) {
+      GST_WARNING_OBJECT (qtdemux, "No available key id for sample");
+    } else {
+      gst_structure_set (ss_info->default_properties, "kid", GST_TYPE_BUFFER,
+          stream->default_kid, NULL);
+    }
+  }
+
   if (!gst_structure_get_uint (ss_info->default_properties, "iv_size",
           &iv_size)) {
     GST_ERROR_OBJECT (qtdemux, "Error getting encryption IV size field");
-- 
2.20.1