diff --git a/bin/ffx.py b/bin/ffx.py
index f1ab0fd..fcd426a 100755
--- a/bin/ffx.py
+++ b/bin/ffx.py
@@ -615,6 +615,29 @@ def convert(ctx,
 
         try:
             sourceStreamDescriptor = getStreamDescriptor(sourcePath)
+
+            # Ensure disposition and tags keys for every stream
+            for substreamIndex in range(len(sourceStreamDescriptor[STREAM_TYPE_AUDIO])):
+                if not 'disposition' in sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition'] = {}
+                if not 'default' in sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition'].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition']['default'] = 0
+                if not 'forced' in sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition'].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition']['forced'] = 0
+            for substreamIndex in range(len(sourceStreamDescriptor[STREAM_TYPE_AUDIO])):
+                if not 'tags' in sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['tags'] = {}
+            for substreamIndex in range(len(sourceStreamDescriptor[STREAM_TYPE_SUBTITLE])):
+                if not 'disposition' in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition'] = {}
+                if not 'default' in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition'].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition']['default'] = 0
+                if not 'forced' in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition'].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition']['forced'] = 0
+            for substreamIndex in range(len(sourceStreamDescriptor[STREAM_TYPE_SUBTITLE])):
+                if not 'tags' in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex].keys():
+                    sourceStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['tags'] = {}
+
             targetStreamDescriptor = sourceStreamDescriptor.copy()
 
         except Exception:
@@ -631,23 +654,19 @@ def convert(ctx,
 
 
         #NOTE: It is currently expected that all source file have the same substream pattern, e.g. coming from the same encoder
-        defaultAudioStreams = [a for a in sourceStreamDescriptor[STREAM_TYPE_AUDIO] if 'disposition' in a.keys() and 'default' in a['disposition'].keys() and a['disposition']['default'] == 1]
-
+        defaultAudioStreams = [a for a in sourceStreamDescriptor[STREAM_TYPE_AUDIO] if a['disposition']['default'] == 1]
         if default_audio == -1 and len(defaultAudioStreams) > 1:
             default_audio = click.prompt("More than one default audio stream detected! Please select stream", type=int)
 
-        forcedAudioStreams = [a for a in sourceStreamDescriptor[STREAM_TYPE_AUDIO] if 'disposition' in a.keys() and 'default' in a['disposition'].keys() and a['disposition']['forced'] == 1]
-
+        forcedAudioStreams = [a for a in sourceStreamDescriptor[STREAM_TYPE_AUDIO] if a['disposition']['forced'] == 1]
         if forced_audio == -1 and len(forcedAudioStreams) > 1:
             forced_audio = click.prompt("More than one forced audio stream detected! Please select stream", type=int)
 
-        defaultSubtitleStreams = [s for s in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE] if 'disposition' in s.keys() and 'default' in s['disposition'].keys() and s['disposition']['default'] == 1]
-
+        defaultSubtitleStreams = [s for s in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE] if s['disposition']['default'] == 1]
         if default_subtitle == -1 and len(defaultSubtitleStreams) > 1:
             default_subtitle = click.prompt("More than one default subtitle stream detected! Please select stream", type=int)
 
-        forcedSubtitleStreams = [s for s in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE] if 'disposition' in s.keys() and 'default' in s['disposition'].keys() and s['disposition']['forced'] == 1]
-
+        forcedSubtitleStreams = [s for s in sourceStreamDescriptor[STREAM_TYPE_SUBTITLE] if s['disposition']['forced'] == 1]
         if forced_subtitle == -1 and len(forcedSubtitleStreams) > 1:
             forced_subtitle = click.prompt("More than one forced subtitle stream detected! Please select stream", type=int)
 
@@ -655,23 +674,15 @@ def convert(ctx,
         #Fix multiple default/forced tags
         if default_audio != -1:
             for substreamIndex in range(len(targetStreamDescriptor[STREAM_TYPE_AUDIO])):
-                if not 'disposition' in targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex].keys():
-                    targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition'] = {}
                 targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition']['default'] = 1 if substreamIndex == default_audio else 0
         if forced_audio != -1:
             for substreamIndex in range(len(targetStreamDescriptor[STREAM_TYPE_AUDIO])):
-                if not 'disposition' in targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex].keys():
-                    targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition'] = {}
                 targetStreamDescriptor[STREAM_TYPE_AUDIO][substreamIndex]['disposition']['forced'] = 1 if substreamIndex == forced_audio else 0
         if default_subtitle != -1:
             for substreamIndex in range(len(targetStreamDescriptor[STREAM_TYPE_SUBTITLE])):
-                if not 'disposition' in targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex].keys():
-                    targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition'] = {}
                 targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition']['default'] = 1 if substreamIndex == default_subtitle else 0
         if forced_subtitle != -1:
             for substreamIndex in range(len(targetStreamDescriptor[STREAM_TYPE_SUBTITLE])):
-                if not 'disposition' in targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex].keys():
-                    targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition'] = {}
                 targetStreamDescriptor[STREAM_TYPE_SUBTITLE][substreamIndex]['disposition']['forded'] = 1 if substreamIndex == forced_subtitle else 0