A playlist is a list of songs. A format is a set of rules about what kind of song plays when. Rotation clocks are how you express the second one.
A clock is a named template for an hour, made of ordered slots. Each slot carries a category, a target duration, selection logic, and a repeat-rule set. Generate against it and you get an hour built to that shape, drawn from your own library.
Categories before clocks
Rotation depends on a categorised library. Tracks belong to audio categories — the familiar power/secondary/gold split, plus imaging buckets like commercials, station IDs and voice tracks. Until that work is done, a clock has nothing meaningful to select from.
This is the unglamorous part, and it is the part that determines whether everything downstream works. A clock can only be as good as the categories underneath it.
Rules that stop the obvious mistakes
Repeat rule sets carry numeric separation limits: how long before the same artist can return, the same title, the same album; maximum plays per hour; whether jingles and voice tracks are exempt. These are edited on the Rules tab alongside the clock builder.
The generator also has relaxation limits. Real libraries are not infinite, and a rule set that cannot be satisfied should degrade gracefully rather than fail. If the ideal pick is unavailable, it takes the best available and tells you.
Preview before you commit
Two preview surfaces exist, and both are worth using.
Preview Hour summarises slots against picks: how many slots were filled, clock layout minutes against the summed audio, whether the hour runs short or long against target. If the layout and the actual audio differ materially, it says so.
Preview Timeline opens a visual hour — slot number, start time, category, chosen track, a duration bar and a rule summary. Click any slot to see the generator's full explanation for that pick, along with any warnings.
Fitting the hour
Hours rarely add up exactly. The generator runs optional stretch and shrink passes to move total audio toward the clock's target duration, and prefers a no-repeat pool when a category has enough clean candidates.
The result is an hour you can defend to a programme director — not because the software says it is right, but because you can open any slot and read why that track is there.