50 lines
2.2 KiB
Rust
50 lines
2.2 KiB
Rust
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//! Lock-free meter state shared from the audio thread to the editor.
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//!
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//! `process()` is the single writer (one store per value per block — decimated, not per sample);
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//! the editor is the single reader (once per frame). All access is wait-free via atomics, so the
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//! realtime thread never blocks. Values are plain scalars (no streaming history yet) — enough for
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//! the per-channel level + gain-reduction bars and the ceiling lamp.
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use nih_plug::prelude::AtomicF32;
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use std::sync::atomic::Ordering;
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/// Metered channels: low, mid, high, then the 'All' aggregate — same order as the compressors.
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pub const NUM_CHANNELS: usize = 4;
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pub struct Meters {
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/// Left output level per channel as a **linear** peak. Peak-with-decay.
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pub level_l: [AtomicF32; NUM_CHANNELS],
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/// Right output level per channel (== left for mono signals). Stored separately so the planned
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/// `|L|GR|R|` layout is a pure editor change; the current bars render `max(L, R)`.
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pub level_r: [AtomicF32; NUM_CHANNELS],
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/// Compressor gain reduction per channel in **dB (>= 0)**. Mono by design — detection is
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/// stereo-linked, so the same gain applies to both channels.
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pub gain_reduction_db: [AtomicF32; NUM_CHANNELS],
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/// Output limiter gain reduction in **dB (>= 0)** — drives the ceiling lamp.
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pub limiter_gr_db: AtomicF32,
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}
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impl Default for Meters {
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fn default() -> Self {
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Self {
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level_l: std::array::from_fn(|_| AtomicF32::new(0.0)),
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level_r: std::array::from_fn(|_| AtomicF32::new(0.0)),
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gain_reduction_db: std::array::from_fn(|_| AtomicF32::new(0.0)),
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limiter_gr_db: AtomicF32::new(0.0),
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}
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}
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}
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/// Update a meter atomic with a new block value using peak-hold-with-decay: jump instantly to a
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/// louder value, ease back down by `decay_weight` (0..1, closer to 1 = slower fall). Keeps meters
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/// from flickering while staying responsive to transients.
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pub fn decay_store(meter: &AtomicF32, block_value: f32, decay_weight: f32) {
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let current = meter.load(Ordering::Relaxed);
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let next = if block_value > current {
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block_value
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} else {
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current * decay_weight + block_value * (1.0 - decay_weight)
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};
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meter.store(next, Ordering::Relaxed);
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}
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