pulp::signal::MaterialChangeDetector Class Reference

Detects a genuine change of material from the gap between the make-up the fast and the slow estimates give the current shape. More...

#include <loudness_compensation.hpp>

Public Types
enum class	Event { none , run_started , run_broken , confirmed }

Public Member Functions
void	reset () noexcept
int	run () const noexcept
double	level_drop_db () const noexcept
	The fast level's fall below the slow one, dB (>= 0 while quieter).
bool	last_was_drop () const noexcept
	Whether the last confirmation came through the quieter-after-louder path.
Event	observe (float fast_db, float slow_db, double frame_lufs=kNoLevel) noexcept
	One audible frame: the make-up the fast and slow shapes give, and (optional) the frame's loudness, for the quieter-after-louder path.
void	hold_off () noexcept

Public Attributes
double	threshold_db = 4.0
int	frames = 12
double	huge_db = 12.0
int	huge_frames = 6
int	holdoff_frames = 6
double	drop_threshold_db = 0.0
	Quieter after louder.
double	drop_level_db = 3.0
double	max_decay_db_per_frame = 0.0
int	drop_min_loud_frames = 0
	... and only after louder material that lasted: the level must have stayed within half of drop_level_db of (or above) its slow average for this many frames before it fell, so a short loud burst in a fast alternation is left to the alternation memory.
double	level_fast_alpha = 0.3
	Per-frame coefficients of the fast and slow level averages (power).
double	level_slow_alpha = 0.03

Static Public Attributes
static constexpr double	kNoLevel = -1.0e300

Detailed Description

Detects a genuine change of material from the gap between the make-up the fast and the slow estimates give the current shape.

The gap must persist: a leaky count – up one for each audible frame above threshold_db, down two for each below – must reach frames (huge_frames while the gap is above huge_db, for a change nobody could miss). So material that is itself uneven (a groove: a kick frame, then a hat frame) still confirms, and a passing moment – a hit, a fill, part of a decay – drains away and is forgotten. Pure bookkeeping; deterministic.

Member Enumeration Documentation

Event

enum class pulp::signal::MaterialChangeDetector::Event

strong

Enumerator
none
run_started
run_broken
confirmed

Member Function Documentation

hold_off()

void pulp::signal::MaterialChangeDetector::hold_off ( )

inlinenoexcept

last_was_drop()

bool pulp::signal::MaterialChangeDetector::last_was_drop ( ) const

inlinenodiscardnoexcept

Whether the last confirmation came through the quieter-after-louder path.

level_drop_db()

double pulp::signal::MaterialChangeDetector::level_drop_db ( ) const

inlinenodiscardnoexcept

The fast level's fall below the slow one, dB (>= 0 while quieter).

observe()

Event pulp::signal::MaterialChangeDetector::observe ( float fast_db, float slow_db, double frame_lufs = kNoLevel )

inlinenoexcept

One audible frame: the make-up the fast and slow shapes give, and (optional) the frame's loudness, for the quieter-after-louder path.

reset()

void pulp::signal::MaterialChangeDetector::reset ( )

inlinenoexcept

run()

int pulp::signal::MaterialChangeDetector::run ( ) const

inlinenodiscardnoexcept

Member Data Documentation

drop_level_db

double pulp::signal::MaterialChangeDetector::drop_level_db = 3.0

drop_min_loud_frames

int pulp::signal::MaterialChangeDetector::drop_min_loud_frames = 0

... and only after louder material that lasted: the level must have stayed within half of drop_level_db of (or above) its slow average for this many frames before it fell, so a short loud burst in a fast alternation is left to the alternation memory.

drop_threshold_db

double pulp::signal::MaterialChangeDetector::drop_threshold_db = 0.0

Quieter after louder.

When the frames' level has fallen at least drop_level_db below its slow average, a smaller gap – drop_threshold_db – counts as a change too: a quieter section after a loud one is a new part, and the energy-weighted estimate is slowest to give the louder past up exactly then. A decay (a hit's tail, a fade) also falls in level, so this path confirms only material whose level is steady over the run: its fitted slope must not fall faster than max_decay_db_per_frame. drop_threshold_db <= 0 turns the path off.

frames

int pulp::signal::MaterialChangeDetector::frames = 12

holdoff_frames

int pulp::signal::MaterialChangeDetector::holdoff_frames = 6

huge_db

double pulp::signal::MaterialChangeDetector::huge_db = 12.0

huge_frames

int pulp::signal::MaterialChangeDetector::huge_frames = 6

kNoLevel

double pulp::signal::MaterialChangeDetector::kNoLevel = -1.0e300

staticconstexpr

level_fast_alpha

double pulp::signal::MaterialChangeDetector::level_fast_alpha = 0.3

Per-frame coefficients of the fast and slow level averages (power).

level_slow_alpha

double pulp::signal::MaterialChangeDetector::level_slow_alpha = 0.03

max_decay_db_per_frame

double pulp::signal::MaterialChangeDetector::max_decay_db_per_frame = 0.0

threshold_db

double pulp::signal::MaterialChangeDetector::threshold_db = 4.0

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The documentation for this class was generated from the following file:

• /home/runner/work/pulp/pulp/core/signal/include/pulp/signal/loudness_compensation.hpp