New XML format questions

[amindfv at mailbox.org]

With the new Kdenlive version I've got (20.12.3), there are a bunch of new things I'm trying to get my head around in the project XML. Here's a snippet with a few of them:

    <playlist id="playlist6">
     <entry producer="1" in="00:00:00.000" out="00:00:22.042">
      <property name="kdenlive:id">2</property>
     </entry>
     <blank length="00:00:01.042"/>
     <entry producer="producer0" in="00:00:01.125" out="00:00:04.958">
      <property name="kdenlive:id">3</property>
     </entry>
     <blank length="00:00:01.208"/>
     <entry producer="1" in="00:00:00.000" out="00:00:04.958">
      <property name="kdenlive:id">2</property>
     </entry>
     <entry producer="producer0" in="00:00:00.000" out="00:00:01.083">
      <property name="kdenlive:id">3</property>
     </entry>
    </playlist>
    <playlist id="playlist7"/>
    <tractor id="tractor3" in="00:00:00.000" out="00:00:34.292">
     <property name="kdenlive:track_name">Video 1</property>
     <property name="kdenlive:trackheight">71</property>
     <property name="kdenlive:timeline_active"/>
     <property name="kdenlive:thumbs_format"/>
     <property name="kdenlive:audio_rec"/>
     <track producer="playlist6"/>
     <track producer="playlist7"/>
    </tractor>

The above makes a Kdenlive track ("Video 1"). In previous versions, this would have been represented as a single playlist. Now there seem to be two playlists - one empty - fed into a tractor.

Here's an example of the new grouping syntax as well:

    <property name="kdenlive:docproperties.groups">[
      {
          "children": [
              {
                  "data": "3:555",
                  "leaf": "clip",
                  "type": "Leaf"
              },
              {
                  "data": "0:555",
                  "leaf": "clip",
                  "type": "Leaf"
              }
          ],
          "type": "AVSplit"
      }
    ]
    </property>


I have many questions. Help with any of them is much appreciated:

  - Why are there two playlists for "Video 1"? What is the purpose of the empty "playlist7"?
  - Entries now have a "kdenlive:id" property. What is this ID? Note in the above the IDs are doubled: there are two different Entries with ID 2, and two with ID 3.
  - In the group syntax, what is the "data" property? As a guess, is it a kdenlive ID and a number of frames from the beginning of the track?
  - What group types are there other than "AVSplit" and "Leaf"? Where can I find a list of the types and their meanings?
  - What "leaf" types are there other than "clip"?

Thanks,
Tom