LevelFollower.h File Reference

Envelope follower for real-time peak and RMS level metering. More...

#include "../Core/AudioBuffer.h"
#include "../Core/AudioSpec.h"
#include "../Core/DspMath.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cmath>
#include <type_traits>

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Classes
class	dspark::LevelFollower< T, MaxChannels >
	Per-channel peak and RMS envelope follower with lock-free readout. More...

Namespaces
namespace	dspark
	Main namespace for the DSPark framework.

Detailed Description

Envelope follower for real-time peak and RMS level metering.

Tracks per-channel peak and RMS levels with lock-free readout for UI metering. Peak uses an asymmetric attack/release one-pole; RMS uses a symmetric one-pole exponential integrator over the squared signal (a VU-style exponential window whose time constant equals the configured window time - not a rectangular moving average). A small constant offset keeps both recursions out of the subnormal range on decay tails; its equilibrium floor sits far below the -100 dB readout floor.

Threading:

• prepare() / reset(): setup thread (not concurrent with process()).
• setAttackMs() / setReleaseMs() / setRmsWindowMs(): any thread. Parameters and coefficients are published atomically; process() picks them up at the next block. A block may observe one changed coefficient before another (benign for metering). Non-finite values are ignored.
• process(): audio thread (stream owner).
• getPeakLevel() / getRmsLevel() / *Db(): any thread (relaxed atomic reads; values are approximate while a block is in flight - metering).

Dependencies: AudioBuffer.h, AudioSpec.h, DspMath.h.

dspark::LevelFollower<float> meter;
meter.prepare(spec);
meter.setAttackMs(1.0f);
meter.setReleaseMs(100.0f);
meter.setRmsWindowMs(300.0f);
 
// In process() (Audio Thread):
meter.process(buffer.toView());
 
// In UI Thread (Safe, lock-free reading):
float peakDb = meter.getPeakLevelDb(0);
float rmsDb  = meter.getRmsLevelDb(0);

Definition in file LevelFollower.h.