Investigate persistent markers

[danrahn]

Plex will wipe out any marker customizations made in the taggings table when media is reanalyzed. However, there is a (seemingly) unused metadata_item_setting_markers table that does appear to persist across reanalysis and triggers intro/credits skip UI:

CREATE TABLE IF NOT EXISTS 'metadata_item_setting_markers' (
    'id'                       INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
    'marker_type'              integer NOT NULL,
    'metadata_item_setting_id' integer NOT NULL,
    'start_time_offset'        integer NOT NULL,
    'end_time_offset'          integer,
    'title'                    varchar(255),
    'created_at'               integer(8),
    'updated_at'               integer(8),
    'extra_data'               varchar(255),
    FOREIGN KEY(metadata_item_setting_id) REFERENCES metadata_item_settings(id) ON DELETE CASCADE);

where marker_type is

marker_type	text
1	intro
2	commercial
3	bookmark
4	resume
5	credits

Is it feasible to use this instead of the taggings table? This introduces some new problems though:

• Each entry is per-user. So a "global" marker would require a new row for each user that has access to the server, and there would need to be a system in place to retroactively apply custom markers to new users.
• Automatic markers that were edited/deleted will still be reset after analysis. This could result in markers overlapping between metadata_item_setting_markers and taggings, so a system to detect those would also be needed. Is that better or worse than the current 'purged marker' system?

Tradeoffs need to be more thoroughly investigated, but for now it may be better to hold off on any changes.