Add library to normalize speech level (Sendevolumenregler SVoR)
Note: This lib has no user yet.
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021c695883
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@ -24,6 +24,7 @@ src/libdebug/libdebug.a
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src/libmobile/libmobile.a
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src/libdisplay/libdisplay.a
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src/libimage/libimage.a
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src/libsendevolumenregler/libsendevolumenregler.a
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src/libcompandor/libcompandor.a
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src/libgoertzel/libgoertzel.a
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src/libjitter/libjitter.a
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@ -57,6 +58,7 @@ src/r2000/radiocom2000
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src/tv/osmotv
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sim/cnetz_sim
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src/test/test_filter
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src/test/test_sendevolumenregler
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src/test/test_compandor
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src/test/test_emphasis
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src/test/test_dms
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@ -79,6 +79,7 @@ AC_OUTPUT(
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src/libmobile/Makefile
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src/libdisplay/Makefile
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src/libimage/Makefile
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src/libsendevolumenregler/Makefile
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src/libcompandor/Makefile
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src/libgoertzel/Makefile
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src/libjitter/Makefile
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@ -6,6 +6,7 @@ SUBDIRS = \
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libdisplay \
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libsample \
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libimage \
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libsendevolumenregler \
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libcompandor \
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libgoertzel \
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libjitter \
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@ -0,0 +1,6 @@
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AM_CPPFLAGS = -Wall -Wextra -g $(all_includes)
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noinst_LIBRARIES = libsendevolumenregler.a
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libsendevolumenregler_a_SOURCES = \
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sendevolumenregler.c
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@ -0,0 +1,115 @@
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/* Sendevolumenregler to be used by B-Netz
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*
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* (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
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* All Rights Reserved
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/* This function keeps the speech level for the transmitter constant.
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*
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* B-Netz specs say that levels are amplified to speech level. The maximum gain
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* is 16 dB. The level may overshoot by 2.6 dB and must lowered to normal level
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* within 20 ms. The level should raise 4.3 dB per second until target level is
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* reached.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include <math.h>
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#include "../libsample/sample.h"
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#include "sendevolumenregler.h"
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#define db2level(db) pow(10, (double)db / 20.0)
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/*
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* Init function
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*
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* abwaerts_dbs = how many dB per second to lower the amplification, if input signal is above dBm0
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* aufwaerts_dbs = how many dB per second to raise the amplification, if input signal is below dBm0
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* maximum_db = limit of the output level above dBm0
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* minimum_db = below this input level, the amplification is not raised, so it stays constant.
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* dbm0_level = target level to be treated as 0 dB
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*
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* Hopefully this is correct
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*
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*/
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void init_sendevolumenregler(sendevolumenregler_t *state, double samplerate, double abwaerts_dbs, double aufwaerts_dbs, double maximum_db, double minimum_db, double dbm0_level)
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{
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memset(state, 0, sizeof(*state));
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state->peak = 1.0;
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state->envelope = 1.0;
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state->dbm0_level = dbm0_level;
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state->step_down = pow(db2level(abwaerts_dbs), 1.0 / samplerate);
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state->step_up = pow(db2level(aufwaerts_dbs), 1.0 / samplerate);
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state->maximum_level = db2level(maximum_db);
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state->minimum_level = db2level(minimum_db);
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}
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/*
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* how to works:
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*
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* if value is above 'peak', raise 'peak' to value instantaniously
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* if value is below 'peak', lower 'peak' by 'step_up' (increase level)
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* if 'peak' is above 'envelope', raise 'envelope' by 'step_down' (decrease level)
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* if 'peak' is below 'envelope', lower 'envelope' to 'peak' (increase level)
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* 'envelope' will not fall below 'minimum_level' (maximum amplification)
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* if 'peak' is 'maximum_level' above 'envelope', raise 'envelope' to 'maximum_level' below 'peak'
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*/
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void sendevolumenregler(sendevolumenregler_t *state, sample_t *samples, int num)
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{
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double value, peak, envelope, step_up, step_down, maximum_level, minimum_level, dbm0_level;
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int i;
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dbm0_level = state->dbm0_level;
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step_up = state->step_up;
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step_down = state->step_down;
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maximum_level = state->maximum_level;
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minimum_level = state->minimum_level;
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peak = state->peak;
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envelope = state->envelope;
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for (i = 0; i < num; i++) {
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/* normalize sample value to dbm0_level level */
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value = *samples / dbm0_level;
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/* 'peak' is the level that raises directly with the value
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* level, but falls as specified by step_up. */
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if (fabs(value) > peak)
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peak = fabs(value);
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else
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peak /= step_up;
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/* 'evelope' is the level that raises with the specified step_down
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* to 'peak', but falls with 'peak'. */
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if (peak > envelope)
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envelope *= step_down;
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else
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envelope = peak;
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/* no envelope below minimum level */
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if (envelope < minimum_level)
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envelope = minimum_level;
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/* raise envelope, if 'peak' exceeds maximum level */
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if (peak / envelope > maximum_level)
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envelope = peak / maximum_level;
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*samples++ = value / envelope * dbm0_level;
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}
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state->envelope = envelope;
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state->peak = peak;
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}
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@ -0,0 +1,14 @@
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typedef struct sendevolumenregler {
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double peak;
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double envelope;
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double step_up;
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double step_down;
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double minimum_level;
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double maximum_level;
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double dbm0_level;
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} sendevolumenregler_t;
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void init_sendevolumenregler(sendevolumenregler_t *state, double samplerate, double abwaerts_dbs, double aufwaerts_dbs, double maximum_db, double minimum_db, double dbm0_level);
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void sendevolumenregler(sendevolumenregler_t *state, sample_t *samples, int num);
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@ -2,6 +2,7 @@ AM_CPPFLAGS = -Wall -g $(all_includes)
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noinst_PROGRAMS = \
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test_filter \
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test_sendevolumenregler \
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test_compandor \
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test_emphasis \
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test_dms \
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$(SOAPY_LIBS)
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endif
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test_sendevolumenregler_SOURCES = test_sendevolumenregler.c
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test_sendevolumenregler_LDADD = \
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$(COMMON_LA) \
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$(top_builddir)/src/libsendevolumenregler/libsendevolumenregler.a \
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-lm
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test_compandor_SOURCES = dummy.x test_compandor.c
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test_compandor_LDADD = \
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@ -0,0 +1,105 @@
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#include <stdio.h>
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#include <stdint.h>
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#include <math.h>
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#include <string.h>
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#include "../libsample/sample.h"
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#include "../libsendevolumenregler/sendevolumenregler.h"
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#define level2db(level) (20 * log10(level))
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#define db2level(db) pow(10, (double)db / 20.0)
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#define SAMPLERATE 48000
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#define ABWAERTS_DBS (2.6 / 0.020) /* 2.6 dB in 20 ms */
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#define AUFWAERTS_DBS 4.3
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#define MINIMUM_DB -16.0
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#define MAXIMUM_DB 2.6
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static double test_frequency[3] = { 1000.0, 4000.0, 300.0 };
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static sample_t samples_plus4db[SAMPLERATE];
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static sample_t samples_minus20db[SAMPLERATE];
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static sample_t samples_0db[SAMPLERATE];
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/* generate 2 samples: one with -4 dB, the other with -16 dB */
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static void generate_test_sample(double test_frequency)
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{
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int i;
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double value;
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for (i = 0; i < SAMPLERATE; i++) {
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value = cos(2.0 * M_PI * test_frequency / (double)SAMPLERATE * i);
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samples_plus4db[i] = value * db2level(4);
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samples_minus20db[i] = value * db2level(-20);
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samples_0db[i] = value;
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}
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}
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static void check_level(sample_t *samples, const char *desc, double target_db, int when)
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{
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int i;
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double last = 0.0, envelope = 0.0;
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int up = 0;
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double factor;
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for (i = 0; i < when; i++) {
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//puts(debug_amplitude(samples[i]));
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if (last < samples[i]) {
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up = 1;
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} else if (last > samples[i]) {
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if (up) {
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envelope = last;
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}
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up = 0;
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}
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#if 0
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if ((i % (SAMPLERATE/(SAMPLERATE/100))) == 0)
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printf("%s: envelope = %.4f (val=%.4f) (when=%d ms)\n", desc, level2db(envelope), envelope, i * 1000 / SAMPLERATE);
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#endif
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last = samples[i];
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}
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factor = envelope / db2level(target_db);
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printf("%s: envelope after %d ms is %.4f db (factor %.4f)\n", desc, i * 1000 / SAMPLERATE, level2db(envelope), factor);
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if (factor > 1.1 || factor < 0.9) {
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printf("**** ERROR: we expected a factor close to 1.0\n");
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}
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}
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int main(void)
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{
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sendevolumenregler_t state;
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sample_t samples[SAMPLERATE * 2];
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int f;
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for (f = 0; f < 3; f++) {
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printf("Testing frequency %.0f Hz:\n", test_frequency[f]);
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generate_test_sample(test_frequency[f]);
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/* increment low level */
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memcpy(samples, samples_minus20db, SAMPLERATE * sizeof(sample_t));
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init_sendevolumenregler(&state, SAMPLERATE, ABWAERTS_DBS, AUFWAERTS_DBS, MAXIMUM_DB, MINIMUM_DB, 1.0);
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sendevolumenregler(&state, samples, SAMPLERATE);
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check_level(samples, "aufwaerts (-20 dB)", AUFWAERTS_DBS - 20.0, 1000 * SAMPLERATE / 1000);
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/* decrement high level */
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memcpy(samples, samples_plus4db, SAMPLERATE * sizeof(sample_t));
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init_sendevolumenregler(&state, SAMPLERATE, ABWAERTS_DBS, AUFWAERTS_DBS, MAXIMUM_DB, MINIMUM_DB, 1.0);
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sendevolumenregler(&state, samples, SAMPLERATE);
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check_level(samples, "abwaerts (+4 dB)", MAXIMUM_DB / 2.0, 10 * SAMPLERATE / 1000);
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check_level(samples, "abwaerts (+4 dB)", 0.0, 20 * SAMPLERATE / 1000);
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/* 0 DB */
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memcpy(samples, samples_0db, SAMPLERATE * sizeof(sample_t));
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init_sendevolumenregler(&state, SAMPLERATE, ABWAERTS_DBS, AUFWAERTS_DBS, MAXIMUM_DB, MINIMUM_DB, 1.0);
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check_level(samples, "unaffected level", 0.0, 1000 * SAMPLERATE / 1000);
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puts("");
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}
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return 0;
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}
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