dspark::LoudnessMeter< T > Class Template Reference

Real-time safe EBU R128 loudness meter. More...

#include <LoudnessMeter.h>

Public Member Functions
void	prepare (double sampleRate, int numChannels=2) noexcept
	Prepares the meter and pre-calculates filter coefficients.
void	prepare (const AudioSpec &spec) noexcept
	Unified API preparation.
void	processBlock (AudioBufferView< const T > buffer) noexcept
	Processes a non-interleaved buffer view (read-only).
void	process (const T *data, int numSamples) noexcept
	Processes a mono block of samples.
void	process (const T *left, const T *right, int numSamples) noexcept
	Processes a stereo block of samples.
T	getMomentaryLUFS () const noexcept
	Reads the Momentary loudness (400 ms window).
T	getShortTermLUFS () const noexcept
	Reads the Short-term loudness (3 second window).
T	getIntegratedLUFS () const noexcept
	Computes the Integrated loudness using standard two-pass gating.
T	getTruePeakDb () const noexcept
	Returns the maximum true peak observed since the last reset.
T	getLoudnessRange () const noexcept
	Computes the EBU R128 Loudness Range (EBU Tech 3342).
void	reset () noexcept
	Clears all measurements and resets filters.

Detailed Description

template<FloatType T>
class dspark::LoudnessMeter< T >

Real-time safe EBU R128 loudness meter.

Implements Momentary (400ms), Short-Term (3s), and Integrated (gated) measurements. Utilizes a constant-memory histogram for infinite integrated loudness tracking without memory allocation or O(N) CPU scaling, ensuring strict RT compliance.

All readout methods (getMomentaryLUFS, etc.) are lock-free and thread-safe to be called from GUI threads while the audio thread is processing.

Template Parameters

T	Sample type (float or double).

Definition at line 56 of file LoudnessMeter.h.

Member Function Documentation

getIntegratedLUFS()

template<FloatType T>

T dspark::LoudnessMeter< T >::getIntegratedLUFS ( ) const

inlinenoexcept

Computes the Integrated loudness using standard two-pass gating.

Note

O(bins) with a constant bin count (no per-block cost growth). Safe to call from any thread.

Returns

Loudness in LUFS (minimum -100.0).

Definition at line 199 of file LoudnessMeter.h.

getLoudnessRange()

template<FloatType T>

T dspark::LoudnessMeter< T >::getLoudnessRange ( ) const

inlinenoexcept

Computes the EBU R128 Loudness Range (EBU Tech 3342).

Short-term (3 s) loudness sampled once per second, gated at -70 LUFS absolute and -20 LU relative; LRA is the spread between the 10th and 95th percentiles. O(bins) and real-time safe like the integrated gate.

Returns

Loudness range in LU (0 if not enough material yet).

Definition at line 263 of file LoudnessMeter.h.

getMomentaryLUFS()

template<FloatType T>

T dspark::LoudnessMeter< T >::getMomentaryLUFS ( ) const

inlinenoexcept

Reads the Momentary loudness (400 ms window).

Returns

Loudness in LUFS (minimum -100.0).

Definition at line 179 of file LoudnessMeter.h.

getShortTermLUFS()

template<FloatType T>

T dspark::LoudnessMeter< T >::getShortTermLUFS ( ) const

inlinenoexcept

Reads the Short-term loudness (3 second window).

Returns

Loudness in LUFS (minimum -100.0).

Definition at line 188 of file LoudnessMeter.h.

getTruePeakDb()

template<FloatType T>

T dspark::LoudnessMeter< T >::getTruePeakDb ( ) const

inlinenoexcept

Returns the maximum true peak observed since the last reset.

Returns

True peak in dBTP (ITU-R BS.1770-4, 4x oversampled estimate).

Definition at line 249 of file LoudnessMeter.h.

prepare() [1/2]

template<FloatType T>

void dspark::LoudnessMeter< T >::prepare ( const AudioSpec &  spec )

inlinenoexcept

Unified API preparation.

Definition at line 88 of file LoudnessMeter.h.

prepare() [2/2]

template<FloatType T>

void dspark::LoudnessMeter< T >::prepare ( double  sampleRate, int  numChannels = 2  )

inlinenoexcept

Prepares the meter and pre-calculates filter coefficients.

A non-finite or non-positive sample rate is ignored (conservative no-op keeping the previous state).

Parameters

sampleRate	Sample rate in Hz (must be > 0 and finite).
numChannels	Accepted for API symmetry; the channel layout is taken from each processed buffer (up to 2 channels are measured).

Definition at line 70 of file LoudnessMeter.h.

process() [1/2]

template<FloatType T>

void dspark::LoudnessMeter< T >::process ( const T *  data, int  numSamples  )

inlinenoexcept

Processes a mono block of samples.

Parameters

data	Pointer to mono audio data.
numSamples	Number of samples to process.

Definition at line 116 of file LoudnessMeter.h.

process() [2/2]

template<FloatType T>

void dspark::LoudnessMeter< T >::process ( const T *  left, const T *  right, int  numSamples  )

inlinenoexcept

Processes a stereo block of samples.

Parameters

left	Pointer to left channel data.
right	Pointer to right channel data.
numSamples	Number of samples per channel.

Definition at line 148 of file LoudnessMeter.h.

processBlock()

template<FloatType T>

void dspark::LoudnessMeter< T >::processBlock ( AudioBufferView< const T >  buffer )

inlinenoexcept

Processes a non-interleaved buffer view (read-only).

The first two channels are measured; additional channels are ignored (multichannel spatial weighting is not implemented).

Parameters

buffer

AudioBufferView to analyze.

Definition at line 101 of file LoudnessMeter.h.

reset()

template<FloatType T>

void dspark::LoudnessMeter< T >::reset ( )

inlinenoexcept

Clears all measurements and resets filters.

Call from the stream owner or a setup thread, not concurrently with the process calls: the accumulators and filter states are plain writer-owned members.

Definition at line 319 of file LoudnessMeter.h.

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

• Analysis/LoudnessMeter.h