Merge branch 'master' into MB_Fixes

* master:
  Aaf adapter target url fix (AcademySoftwareFoundation#628)
  C++ Error documentation additions (AcademySoftwareFoundation#620)
  Issue 622 (AcademySoftwareFoundation#624)
  Add Kdenlive adapter (AcademySoftwareFoundation#618)

Author: andrewmoore-nz

contrib/opentimelineio_contrib/adapters/aaf_adapter/aaf_writer.py

@@ -49,6 +49,32 @@
 AAF_OPERATIONDEF_SUBMASTER = uuid.UUID("f1db0f3d-8d64-11d3-80df-006008143e6f")
 
 
+def _is_considered_gap(thing):
+    """Returns whether or not thiing can be considered gap.
+
+    TODO: turns generators w/ kind "Slug" inito gap.  Should probably generate
+          opaque black instead.
+    """
+    if isinstance(thing, otio.schema.Gap):
+        return True
+
+    if (
+            isinstance(thing, otio.schema.Clip)
+            and isinstance(
+                thing.media_reference,
+                otio.schema.GeneratorReference)
+    ):
+        if thing.media_reference.generator_kind in ("Slug",):
+            return True
+        else:
+            raise otio.exceptions.NotSupportedError(
+                "AAF adapter does not support generator references of kind"
+                " '{}'".format(thing.media_reference.generator_kind)
+            )
+
+    return False
+
+
 class AAFAdapterError(otio.exceptions.OTIOError):
     pass
 
@@ -144,7 +170,7 @@ def validate_metadata(timeline):
 
     for child in timeline.each_child():
         checks = []
-        if isinstance(child, otio.schema.Gap):
+        if _is_considered_gap(child):
             checks = [
                 __check(child, "duration().rate").equals(edit_rate)
             ]
@@ -223,6 +249,8 @@ def _generate_empty_mobid(clip):
     clip_mob_ids = {}
 
     for otio_clip in input_otio.each_clip():
+        if _is_considered_gap(otio_clip):
+            continue
         for strategy in strategies:
             mob_id = strategy(otio_clip)
             if mob_id:
@@ -281,7 +309,7 @@ def __init__(self, root_file_transcriber, otio_track):
 
     def transcribe(self, otio_child):
         """Transcribe otio child to corresponding AAF object"""
-        if isinstance(otio_child, otio.schema.Gap):
+        if _is_considered_gap(otio_child):
             filler = self.aaf_filler(otio_child)
             return filler
         elif isinstance(otio_child, otio.schema.Transition):

contrib/opentimelineio_contrib/adapters/contrib_adapters.plugin_manifest.json

@@ -56,6 +56,13 @@
             "execution_scope": "in process",
             "filepath": "xges.py",
             "suffixes": ["xges"]
+        },
+        {
+            "OTIO_SCHEMA": "Adapter.1",
+            "name": "kdenlive",
+            "execution_scope": "in process",
+            "filepath": "kdenlive.py",
+            "suffixes": ["kdenlive"]
         }
     ],
     "schemadefs" : [