Almost every automation system offers a crossfade setting: one number, in milliseconds, applied to every transition. It is the wrong model, and you can hear why within an hour of listening.
A station ID that fades up from silence sounds broken. A voice track whose first syllable is buried under the outgoing song sounds unprofessional. Yet a single global crossfade does exactly that.
Three different transitions
PlayOnRadio classifies each item as either music or imaging — the latter covering voice tracks, jingles, commercials, and station IDs, identified from track type or from rotation category codes such as ADS, ID and VT. Transitions are then handled by three separate rules:
- Music to music — a genuine equal-power crossfade, cosine out on the old deck and sine in on the new one, so perceived loudness stays constant through the blend.
- Music to imaging — the music fades out, but the incoming jingle or voice track holds at unity gain for the whole overlap. It starts at full level, the way it would if a presenter fired it manually.
- Imaging to music — the outgoing break is hard-cut with no ramp down, and the music fades in underneath. A jingle should end when it ends, not dissolve.
Break to break is an instant swap. Two short imaging items do not need an equal-power ramp between them.
The timing trap
The imaging-to-music rule creates a subtle problem worth understanding. Because the outgoing deck is cut the moment the handover runs, firing that handover early would clip the tail off a voice track — the presenter's last word simply disappears.
So for imaging items, the lookahead window is deliberately capped to around 120 milliseconds while playing, rather than the full crossfade length. Auto-advance arms only in the final moments of the file. The near-end threshold drops to roughly 8 milliseconds so that even these tiny windows still fire reliably.
For the same reason, cue markers that request an early handover are not applied to imaging items at all. Those markers exist for music mix timing; pairing them with a hard cut would truncate the break.
Why this is worth the complexity
None of this is visible in a feature list. It shows up as a station that sounds like someone is driving it, and that is the only measure that matters.