Plex Play Queue API

The playqueue feature within a media provider A play queue represents the current list of media for playback. Although queues are persisted by the server, they should be regarded by the user as a fairly lightweight, an ephemeral list of items queued up for playback in a session. There is generally one active queue for each type of media (music, video, photos) that can be added to or destroyed and replaced with a fresh queue. Play Queues has a region, which we refer to in this doc (partially for historical reasons) as "Up Next". This region is defined by `playQueueLastAddedItemID` existing on the media container. This follows iTunes' terminology. It is a special region after the currently playing item but before the originally-played items. This enables "Party Mode" listening/viewing, where items can be added on-the-fly, and normal queue playback resumed when completed. You can visualize the play queue as a sliding window in the complete list of media queued for playback. This model is important when scaling to larger play queues (e.g. shuffling 40,000 audio tracks). The client only needs visibility into small areas of the queue at any given time, and the server can optimize access in this fashion. All created play queues will have an empty "Up Next" area - unless the item is an album and no `key` is provided. In this case the "Up Next" area will be populated by the contents of the album. This is to allow queueing of multiple albums - since the 'Add to Up Next' will insert after all the tracks. This means that If you're creating a PQ from an album, you can only shuffle it if you set `key`. This is due to the above implicit queueing of albums when no `key` is provided as well as the current limitation that you cannot shuffle a PQ with an "Up Next" area. The play queue window advances as the server receives timeline requests. The client needs to retrieve the play queue as the “now playing” item changes. There is no play queue API to update the playing item.