ts::Equalizer Class Reference

The GS four-band EQ: a low shelf and a high shelf, in series, on a stereo bus. More...

#include <tabulasonora/equalizer.hpp>

Public Member Functions
	Equalizer (const EffectPresets &presets) noexcept
	Creates an equalizer over a preset set, which must outlive it.
bool	available () const noexcept
	Whether this equalizer can actually filter.
bool	is_flat () const noexcept
	Whether the current settings would change the signal.
void	set_low_frequency (int value) noexcept
	Sets one of the four parameters, as 40 02 00–03 names them.
void	set_low_gain (int value) noexcept
void	set_high_frequency (int value) noexcept
void	set_high_gain (int value) noexcept
void	reset () noexcept
	Returns the block state to power-on: flat, with both corners at their lower choice.
void	clear () noexcept
	Clears the filter memory without changing the settings.
void	process (std::span< float > left, std::span< float > right) noexcept
	Filters a stereo block in place.

Static Public Attributes
static constexpr int	flat_gain = 0x40
	The flat setting: 40 02 01 and 40 02 03 centred, both corners at their lower choice.

Detailed Description

The GS four-band EQ: a low shelf and a high shelf, in series, on a stereo bus.

Four bands in Roland's naming, two in this engine's: 40 02 exposes a frequency and a gain for each of low and high, and the two channels take the same pair. The engine writes each band's three coefficients to a left register and a right register with identical values (fx_eq_band_preset_apply sends every word twice, to 0xe6-0xe8 and again to 0xf3-0xf5), so the stereo image is untouched and only the spectrum moves.

This is not a send. It sits inline on the parts that switch it on with 40 4x 20, which is why it takes a stereo buffer and rewrites it rather than producing a wet signal to be mixed.

Constructor & Destructor Documentation

Equalizer()

ts::Equalizer::Equalizer ( const EffectPresets & presets )

explicitnoexcept

Creates an equalizer over a preset set, which must outlive it.

A set with no EQ coefficients — one parsed from a pinned presets.json, which carries none — makes every process a no-op rather than a flat filter. Those are the same thing in theory and not in practice: running audio through a filter whose coefficients are all default would be silently wrong, and doing nothing is visibly nothing.

Member Function Documentation

available()

bool ts::Equalizer::available ( ) const

inlinenodiscardnoexcept

Whether this equalizer can actually filter.

is_flat()

bool ts::Equalizer::is_flat ( ) const

inlinenodiscardnoexcept

Whether the current settings would change the signal.

Both gains flat means both shelves are exactly unity, so the whole stage can be skipped without any difference in output — the identity is algebraic, not an approximation.

set_low_frequency()

void ts::Equalizer::set_low_frequency ( int value )

noexcept

Sets one of the four parameters, as 40 02 00–03 names them.

Values outside the engine's accepted ranges are ignored, as the engine ignores them: the frequency selectors take 0 or 1, and the gains take 0x34–0x4C.

set_low_gain()

void ts::Equalizer::set_low_gain ( int value )

noexcept

set_high_frequency()

void ts::Equalizer::set_high_frequency ( int value )

noexcept

set_high_gain()

void ts::Equalizer::set_high_gain ( int value )

noexcept

reset()

void ts::Equalizer::reset ( )

noexcept

Returns the block state to power-on: flat, with both corners at their lower choice.

clear()

void ts::Equalizer::clear ( )

noexcept

Clears the filter memory without changing the settings.

process()

void ts::Equalizer::process ( std::span< float > left, std::span< float > right )

noexcept

Filters a stereo block in place.

Member Data Documentation

flat_gain

int ts::Equalizer::flat_gain = 0x40

staticconstexpr

The flat setting: 40 02 01 and 40 02 03 centred, both corners at their lower choice.

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

• include/tabulasonora/equalizer.hpp