sampled-supplier-vs-per-handle-reapply

name

sampled-supplier-vs-per-handle-reapply

description

Two playback backends need opposite plumbing for the same setting — one whose per-stream consumers sample a shared field needs no push at all, one whose every new handle starts blank needs an explicit re-apply at each creation site. Use when a setting reaches the current track but not the next one, when it survives on one platform and not the other, or when a level set on several handles keeps reverting.

Sampled supplier, or re-apply per handle

A playback-wide setting — volume, speed, a fade factor, a filter curve — has to reach every player object that is alive right now and every one created later. There are two backend shapes, and they want opposite code.

Sampling backend. Each stream gets its own consumer, and every consumer closes over one shared field. Correctness comes from the factory, not from any push:

@Volatile private var currentCurve: EqualizerCurve = EqualizerCurve.FLAT

private fun createPlayer(): Player {
    val equalizer = EqualizerAudioProcessor { currentCurve }   // sampled per buffer
    …
}

override fun setEqualizer(bands: List<Float>, preampDb: Float) {
    currentCurve = EqualizerCurve(bands, preampDb)             // that is the whole setter
}

Handle-per-item backend. A fresh handle starts at the engine's defaults — full volume, 1.0× speed, empty filter chain — so anything in force has to be re-asserted on the handle, at every site that creates one: