ADR-0024: A Track Left Paused Is Not Playing for Ever, and a Room With Nothing Playing Is Dim

Context

Pause iTunes and walk away, and the stand goes on showing the album for as long as nothing else plays: hours, overnight. The console says “Paused on iTunes” over the same sleeve. Neither is false, and neither is what the room is doing, which is nothing.

Nothing in EdS has a way to say “nothing is playing” to the stand. lightd lights the room when a cover arrives and does nothing otherwise, on purpose: that is how Spotify is reported without lighting it (ADR-0016). So a cover not being sent already has a meaning, and it is “leave the room as it is”.

Options considered

lightd reads current and dims on paused. lightd would know about tracks and play states, which is the knowledge ADR-0009 keeps on the other side of the cover topic.

The driver stops reporting a paused track after a while. Each driver would grow the same timer, and iTunes would be misreported at its source: the console’s list of players should go on saying what each one is doing.

A new field in current, idle, leaving the track and the cover there. Honest, and every subscriber would have to learn it, the firmware’s included; one that had not would show the track as before. And the stand follows the cover topic, not current.

nowplayd says stopped, and takes the cover away. No new field: current is a state every reader already reads, and the cover topic is emptied, which no reader can take for a cover.

Decision

When the current track has been paused for NP_IDLE_AFTER, fifteen seconds, nowplayd publishes current as stopped, with no track, and empties the cover topics. lightd answers an emptied cover topic with an idle scene: steady, warm, and dim.

• The source is still named in that current, and commands still go to it. A pause is undone from where it was made: the screen’s play button works on a track that is no longer shown.
• Nobody reporting at all goes the same way after the same wait, with no source named. Before the wait it is as it was, so an agent restarting does not dim the room.
• Stopped and still current waits five minutes (NP_IDLE_AFTER_STOPPED). That is a source being held (ADR-0023). A record between its sides keeps its sleeve; a turntable left on with nothing on it does not light the room all night. This was first written as “left alone”, and was wrong within a minute of being deployed: the turntable was on and silent, a track paused in iTunes was not the winner, and the room stayed lit at full (CHG-0016).
• The wait is counted from when the source says it paused, where that is in the past. A track paused an hour ago is idle the moment nowplayd starts.
• Emptied means no cover; not sent means no change. The two are kept apart. Spotify’s track sends no cover and the room stays as it was.
• The idle scene is lightd’s (scene.Idle): solid, 255, 170, 90, at 0.15. It is the scene the firmware starts with, so an idle stand and one just switched on are the same sight. It is not dark: a dark stand cannot be told from a dead one.
• lightd takes hearing no cover, five seconds after subscribing, as an emptied topic. An emptied retained topic is not delivered to a late subscriber, and a lightd that started while the room was idle would otherwise never be told.
• Playing again publishes everything again, the same cover and its look included, and lightd lights the room from a cover it has already held.

Consequences

• The stand and the console say the same thing as the room. The console needed no change: it already shows “Nothing is playing” for stopped, an emptied cover as none, and the stand from the scene it was sent.
• “Stopped” on current now has two meanings: nothing loaded, and paused too long. The per-source topics still tell them apart, and the console’s list of players still says “paused”.
• The paused track cannot be seen on the cover screen, only resumed from it. It shows the record, and its buttons.
• Fifteen seconds is short. A pause to answer the door dims the room. That is what was asked for, and it is a setting.
• lightd knows one thing more: that a topic can be empty. It still is not told what stopped, or that anything did.
• A lightd restart with no cover retained dims the stand, where before it left it alone. With the HTTP input only, nothing changes: the rule is the cover topic’s.
• An agent that is down for more than fifteen seconds dims the room.

What would settle it

Tested as sequences of events in nowplayd’s hub and publisher, and in lightd’s server; the broker test for an emptied topic was turned around, from “not handed on” to “handed on as no cover”.

Not yet shown:

• iTunes paused: fifteen seconds later the stand is dim and the console says nothing is playing, with the stand drawn dim.
• Play pressed on the cover screen after that: iTunes plays, and the stand is lit from the same cover.
• The services restarted with iTunes paused long ago: the stand is not lit first.
• The turntable on and silent for five minutes: the stand is dim. Then a record: lit from its sleeve.