Being new to Kodi and poking around its JSON-RPC interface, I noticed that it exports three different playlist objects (numbered 0 through 2), ostensibly for audio, video and pictures, that can be manipulated through the
Playlist interface. What is the story or reason behind this division into three playlists? Is it to make it possible to add items to two different playlist objects and thus play back e.g. a video file and a (different) music file at the same time? (And is that in fact currently possible?) Or is there some other (technical? historical?) reason?
as I've found in my implementation of this interface, only the audio playlist 0 and image playlist 2 can be used and played back simultaneously, and this require parallel playlists.
in practice, this is the only combination that really makes sense.
I don't know the history of this but imho the proper way to playback audio with video is to encode and package it what way, which is already supported.
otherwise you get into implementation specific functionality... mute the video's audio only to replace it with other audio?... what about mute the video's picture and replace it with a image playlist... I can think of an application for these, but point being I rather KODI focus on core functionality.