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Add limiter support (with limiter from signalsmith-audio-basics)
This adds limiter support by using Signalsmith Audio Basics C++ header-only library (see https://signalsmith-audio.co.uk/code/ and https://github.com/Signalsmith-Audio/basics) Path to Signalsmith basics lib have to be supplied to cmake in the environment variable SIGNALSMITH_AUDIO_BASICS_PATH The limiter is applied in fluid_rvoice_mixer_process_fx after chorus and reverb effects. In the audio drivers that mix effects and dry audio in one buffer, the limiting will be applied to the resulting buffer. In audio drivers that do this separately (for example, Jack driver), the limiting will be applied only to the dry buffer
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‎CMakeLists.txt‎

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@@ -102,6 +102,7 @@ option ( enable-threads "enable multi-threading support (such as parallel voice
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option ( enable-openmp "enable OpenMP support (parallelization of soundfont decoding, vectorization of voice mixing, etc.)" on )
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option ( enable-unicode "enable UNICODE build for Windows" on )
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option ( enable-native-dls "compile native DLS support (requires C++17)" on )
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option ( enable-limiter "compile Limiter support (requires signalsmith-audio)" off )
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106107
set ( osal "glib" CACHE STRING "OS abstraction to use, provided by src/utils/fluid_sys_${osal}.*" )
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@@ -799,6 +800,16 @@ if ( enable-libinstpatch )
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endif ()
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endif ( enable-libinstpatch )
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unset ( LIMITER_SUPPORT CACHE )
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if ( enable-limiter )
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find_path ( SIGNALSMITH_AUDIO_BASICS include/signalsmith-basics/limiter.h
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HINTS ENV SIGNALSMITH_AUDIO_BASICS_PATH NO_CACHE )
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if ( SIGNALSMITH_AUDIO_BASICS )
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set ( LIMITER_SUPPORT 1 )
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set ( LIMITER 1 )
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endif ( SIGNALSMITH_AUDIO_BASICS )
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endif ( enable-limiter )
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# manipulate some variables to setup a proper test env
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set(TEST_SOUNDFONT "${FluidSynth_SOURCE_DIR}/sf2/VintageDreamsWaves-v2.sf2")
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set(TEST_SOUNDFONT_UTF8_1 "${FluidSynth_SOURCE_DIR}/sf2/\\xE2\\x96\\xA0VintageDreamsWaves-v2\\xE2\\x96\\xA0.sf2")

‎cmake_admin/report.cmake‎

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@@ -158,6 +158,16 @@ endif ( LIBSNDFILE_SUPPORT )
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set ( MISC_REPORT "\nMiscellaneous support:\n" )
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if ( LIMITER_SUPPORT )
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set ( MISC_REPORT "${MISC_REPORT} Limiter: yes\n" )
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else ( LIMITER_SUPPORT )
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if ( SIGNALSMITH_AUDIO_BASICS STREQUAL SIGNALSMITH_AUDIO_BASICS-NOTFOUND )
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set ( MISC_REPORT "${MISC_REPORT} Limiter: no (signalsmith-audio/basics not found)\n" )
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else ( SIGNALSMITH_AUDIO_BASICS STREQUAL SIGNALSMITH_AUDIO_BASICS-NOTFOUND )
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set ( MISC_REPORT "${MISC_REPORT} Limiter: no\n" )
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endif ( SIGNALSMITH_AUDIO_BASICS STREQUAL SIGNALSMITH_AUDIO_BASICS-NOTFOUND )
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endif ( LIMITER_SUPPORT )
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if ( DBUS_SUPPORT )
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set ( MISC_REPORT "${MISC_REPORT} D-Bus: yes\n" )
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else ( DBUS_SUPPORT )

‎src/CMakeLists.txt‎

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@@ -195,6 +195,16 @@ set ( libfluidsynth_SOURCES
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bindings/fluid_ladspa.h
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)
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if ( LIMITER_SUPPORT )
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set ( fulid_limiter_SOURCES
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rvoice/fluid_limiter.c
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rvoice/fluid_limiter.h
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rvoice/fluid_limiter_impl.cpp
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rvoice/fluid_limiter_impl.h
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)
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set_source_files_properties(rvoice/fluid_limiter_impl.cpp PROPERTIES COMPILE_FLAGS "-I${SIGNALSMITH_AUDIO_BASICS}/include -std=c++11")
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endif ( LIMITER_SUPPORT )
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set ( fluid_osal_SOURCES utils/fluid_sys_${osal}.h )
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if ( osal STREQUAL "cpp11" )
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set ( fluid_osal_SOURCES ${fluid_osal_SOURCES} utils/fluid_sys_${osal}.cpp )
@@ -281,6 +291,7 @@ add_library ( libfluidsynth-OBJ OBJECT
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${public_HEADERS}
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${public_main_HEADER}
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${VersionFilesOutputVariable}
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${fulid_limiter_SOURCES}
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)
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target_include_directories ( libfluidsynth-OBJ PRIVATE

‎src/config.cmake‎

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@@ -136,6 +136,9 @@
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/* Include the LADSPA Fx unit */
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#cmakedefine LADSPA @LADSPA_SUPPORT@
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/* Include the LIMITER */
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#cmakedefine LIMITER @LIMITER_SUPPORT@
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/* Define to enable IPV6 support */
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#cmakedefine IPV6_SUPPORT @IPV6_SUPPORT@
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‎src/rvoice/fluid_limiter.c‎

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/******************************************************************************
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* FluidSynth - A Software Synthesizer
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*
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* Copyright (C) 2025 Neoharp development team
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see
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* <https://www.gnu.org/licenses/>.
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*
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*/
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#include "fluidsynth_priv.h"
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#ifdef LIMITER
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#include "fluid_limiter.h"
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#include "fluid_limiter_impl.h"
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#include "fluid_sys.h"
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/*----------------------------------------------------------------------------
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Limiter API
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-----------------------------------------------------------------------------*/
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/*
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* Creates a limiter with default parameters
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*
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* @param sample_rate actual sample rate needed in Hz.
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* @return pointer on the new limiter or NULL if memory error.
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* Limiter API.
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*/
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fluid_limiter_t*
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new_fluid_limiter(fluid_real_t sample_rate, fluid_limiter_settings_t* settings)
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{
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fluid_limiter_t* lim;
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if(sample_rate <= 0)
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{
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return NULL;
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}
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lim = fluid_limiter_impl_new(sample_rate, settings);
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if(lim == NULL)
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{
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return NULL;
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}
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return lim;
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}
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/*
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* free the limiter.
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* @param lim pointer on limiter to free.
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* Limiter API.
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*/
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void
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delete_fluid_limiter(fluid_limiter_t *lim)
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{
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fluid_return_if_fail(lim != NULL);
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fluid_limiter_impl_delete(lim);
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}
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/*
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* Applies a sample rate change on the limiter.
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*
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* @param lim the limiter.
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* @param sample_rate new sample rate value
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* @return FLUID_OK if success, FLUID_FAILED if lim is NULL
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* Limiter API.
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*/
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int
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fluid_limiter_samplerate_change(fluid_limiter_t *lim, fluid_real_t sample_rate)
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{
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int status = FLUID_OK;
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fluid_return_val_if_fail(lim != NULL, FLUID_FAILED);
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fluid_limiter_impl_set_sample_rate(lim, sample_rate);
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return status;
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}
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/*-----------------------------------------------------------------------------
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* Run the limiter
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* @param lim pointer on limiter.
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* @param buf_l left buffer to process (will be modified in-place)
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* @param buf_r right buffer to process (will be modified in-place)
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* Limiter API.
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-----------------------------------------------------------------------------*/
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void
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fluid_limiter_run(fluid_limiter_t *lim, fluid_real_t *buf_l, fluid_real_t *buf_r, int block_count)
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{
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int i;
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fluid_real_t* bufs[FLUID_LIMITER_NUM_CHANNELS_AT_ONCE];
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for (i = 0; i < block_count; i++)
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{
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#if FLUID_LIMITER_NUM_CHANNELS_AT_ONCE < 2
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#error "expected FLUID_LIMITER_NUM_CHANNELS_AT_ONCE >= 2"
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#endif
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bufs[0] = buf_l + i*FLUID_BUFSIZE;
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bufs[1] = buf_r + i*FLUID_BUFSIZE;
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fluid_limiter_impl_process_buffers(lim, bufs);
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}
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}
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#endif /* LIMITER */

‎src/rvoice/fluid_limiter.h‎

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@@ -0,0 +1,54 @@
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/* FluidSynth - A Software Synthesizer
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*
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* Copyright (C) 2003 Peter Hanappe and others.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see
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* <https://www.gnu.org/licenses/>.
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*/
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#ifndef _FLUID_LIMITER_H
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#define _FLUID_LIMITER_H
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#ifdef LIMITER
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// how many channel buffers to process at once
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// maybe if we want to parallelize, we might set this to 1
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#define FLUID_LIMITER_NUM_CHANNELS_AT_ONCE 2
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typedef struct {
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fluid_real_t input_gain;
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fluid_real_t output_limit;
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fluid_real_t attack_ms;
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fluid_real_t hold_ms;
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fluid_real_t release_ms;
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int smoothing_stages;
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fluid_real_t link_channels;
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} fluid_limiter_settings_t;
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typedef void fluid_limiter_t;
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fluid_limiter_t*
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new_fluid_limiter(fluid_real_t sample_rate, fluid_limiter_settings_t* settings);
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void delete_fluid_limiter(fluid_limiter_t* lim);
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int fluid_limiter_samplerate_change(fluid_limiter_t* lim, fluid_real_t sample_rate);
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void
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fluid_limiter_run(fluid_limiter_t *lim, fluid_real_t *buf_l, fluid_real_t *buf_r, int block_count);
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#endif /* LIMITER */
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#endif /* _FLUID_LIMITER_H */

‎src/rvoice/fluid_limiter_impl.cpp‎

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/* FluidSynth - A Software Synthesizer
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*
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* Copyright (C) 2003 Peter Hanappe and others.
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*
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* This library is free software; you can redistribute it and/or
6+
* modify it under the terms of the GNU Lesser General Public License
7+
* as published by the Free Software Foundation; either version 2.1 of
8+
* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
11+
* WITHOUT ANY WARRANTY; without even the implied warranty of
12+
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13+
* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
16+
* License along with this library; if not, see
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* <https://www.gnu.org/licenses/>.
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*/
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#include "fluidsynth_priv.h"
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#ifdef LIMITER
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#include "fluid_limiter.h"
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#include "fluid_limiter_impl.h"
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#include "signalsmith-basics/limiter.h"
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#ifdef WITH_FLOAT
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using Limiter = signalsmith::basics::LimiterFloat;
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#else
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using Limiter = signalsmith::basics::LimiterDouble;
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#endif
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extern "C" void fluid_limiter_impl_set_sample_rate(fluid_limiter_t* lim, fluid_real_t sample_rate)
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{
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((Limiter*)lim)->configure(sample_rate, FLUID_BUFSIZE, FLUID_LIMITER_NUM_CHANNELS_AT_ONCE);
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}
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extern "C" fluid_limiter_t* fluid_limiter_impl_new(fluid_real_t sample_rate, fluid_limiter_settings_t* settings)
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{
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auto lim = new Limiter(settings->attack_ms + settings->hold_ms);
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lim->inputGain = settings->input_gain;
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lim->outputLimit = settings->output_limit;
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lim->attackMs = settings->attack_ms;
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lim->holdMs = settings->hold_ms;
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lim->releaseMs = settings->release_ms;
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lim->smoothingStages = settings->smoothing_stages;
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lim->linkChannels = settings->link_channels;
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if (! lim->configure(sample_rate, FLUID_BUFSIZE,
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FLUID_LIMITER_NUM_CHANNELS_AT_ONCE,
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FLUID_LIMITER_NUM_CHANNELS_AT_ONCE) )
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{
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FLUID_LOG(FLUID_WARN, "limiter parameters was not accepted");
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}
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return lim;
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}
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extern "C" void fluid_limiter_impl_delete(fluid_limiter_t* lim)
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{
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delete (Limiter*)lim;
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}
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extern "C" void fluid_limiter_impl_process_buffers(
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fluid_limiter_t* lim,
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fluid_real_t* bufs[FLUID_LIMITER_NUM_CHANNELS_AT_ONCE])
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{
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((Limiter*)lim)->process(bufs, FLUID_BUFSIZE);
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}
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#endif /* LIMITER */

‎src/rvoice/fluid_limiter_impl.h‎

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/******************************************************************************
2+
* FluidSynth - A Software Synthesizer
3+
*
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* Copyright (C) 2025 Neoharp development team
5+
*
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* This library is free software; you can redistribute it and/or
7+
* modify it under the terms of the GNU Lesser General Public License
8+
* as published by the Free Software Foundation; either version 2.1 of
9+
* the License, or (at your option) any later version.
10+
*
11+
* This library is distributed in the hope that it will be useful, but
12+
* WITHOUT ANY WARRANTY; without even the implied warranty of
13+
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14+
* Lesser General Public License for more details.
15+
*
16+
* You should have received a copy of the GNU Lesser General Public
17+
* License along with this library; if not, see
18+
* <https://www.gnu.org/licenses/>.
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*
20+
*/
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#ifndef _FLUID_LIMITER_IMPL_H
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#define _FLUID_LIMITER_IMPL_H
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#ifdef __cplusplus
26+
extern "C" {
27+
#endif
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void fluid_limiter_impl_set_sample_rate(fluid_limiter_t*lim, fluid_real_t sample_rate);
30+
fluid_limiter_t* fluid_limiter_impl_new(fluid_real_t sample_rate, fluid_limiter_settings_t* settings);
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void fluid_limiter_impl_delete(fluid_limiter_t* lim);
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void fluid_limiter_impl_process_buffers(fluid_limiter_t* lim, fluid_real_t* bufs[FLUID_LIMITER_NUM_CHANNELS_AT_ONCE]);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _FLUID_LIMITER_IMPL_H */

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