Restructure: Move emphasis from common code to 'libemphasis'

4 files changed, 1 insertions, 166 deletions

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 02bdf9f..56b4c84 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -6,7 +6,6 @@ libcommon_a_SOURCES = \
 	sample.c \
 	debug.c \
 	sound_alsa.c \
-	emphasis.c \
 	compandor.c \
 	fft.c \
 	fm_modulation.c \
diff --git a/src/common/emphasis.c b/src/common/emphasis.c
deleted file mode 100644
index 08f944a..0000000
--- a/src/common/emphasis.c
+++ /dev/null
@@ -1,140 +0,0 @@
-/* Pre-Emphasis and De-Emphasis implementation
- *
- * (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
- * All Rights Reserved
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <stdio.h>
-#include <stdint.h>
-#include <string.h>
-#include <math.h>
-#include "sample.h"
-#include "../libfilter/iir_filter.h"
-#include "emphasis.h"
-#include "debug.h"
-
-#define PI		M_PI
-
-#define CUT_OFF_H	100.0	/* cut-off frequency for high-pass filter */
-#define CUT_OFF_L	4000.0	/* cut-off frequency for low-pass filter */
-
-static void gen_sine(sample_t *samples, int num, int samplerate, double freq)
-{
-	int i;
-
-	for (i = 0; i < num; i++)
-		samples[i] = cos(2.0 * M_PI * freq / (double)samplerate * (double)i);
-}
-
-static double get_level(sample_t *samples, int num)
-{
-	int i;
-	double envelope = 0;
-	for (i = num/2; i < num; i++) {
-		if (samples[i] > envelope)
-			envelope = samples[i];
-	}
-
-	return envelope;
-}
-
-int init_emphasis(emphasis_t *state, int samplerate, double cut_off)
-{
-	double factor;
-	sample_t test_samples[samplerate / 10];
-
-	memset(state, 0, sizeof(*state));
-
-	/* exp (-2 * PI * CUT_OFF * delta_t) */
-	factor = exp(-2.0 * PI * cut_off / (double)samplerate); /* 1/samplerate == delta_t */
-
-	PDEBUG(DDSP, DEBUG_DEBUG, "Emphasis factor = %.3f\n", factor);
-	state->p.factor = factor;
-	state->p.amp = 1.0;
-	state->d.factor = factor;
-	state->d.amp = 1.0;
-
-	/* do not de-emphasis below CUT_OFF_H */
-	iir_highpass_init(&state->d.hp, CUT_OFF_H, samplerate, 1);
-
-	/* do not pre-emphasis above CUT_OFF_L */
-	iir_lowpass_init(&state->p.lp, CUT_OFF_L, samplerate, 1);
-
-	/* calibrate amplification to be neutral at 1000 Hz */
-	gen_sine(test_samples, sizeof(test_samples) / sizeof(test_samples[0]), samplerate, 1000.0);
-	pre_emphasis(state, test_samples, sizeof(test_samples) / sizeof(test_samples[0]));
-	state->p.amp = 1.0 / get_level(test_samples, sizeof(test_samples) / sizeof(test_samples[0]));
-	gen_sine(test_samples, sizeof(test_samples) / sizeof(test_samples[0]), samplerate, 1000.0);
-	de_emphasis(state, test_samples, sizeof(test_samples) / sizeof(test_samples[0]));
-	state->d.amp = 1.0 / get_level(test_samples, sizeof(test_samples) / sizeof(test_samples[0]));
-
-	return 0;
-}
-
-void pre_emphasis(emphasis_t *state, sample_t *samples, int num)
-{
-	double x, y, x_last, factor, amp;
-	int i;
-
-	iir_process(&state->p.lp, samples, num);
-
-	x_last = state->p.x_last;
-	factor = state->p.factor;
-	amp = state->p.amp;
-
-	for (i = 0; i < num; i++) {
-		x = *samples;
-
-		/* pre-emphasis */
-		y = x - factor * x_last;
-
-		x_last = x;
-
-		*samples++ = amp * y;
-	}
-
-	state->p.x_last = x_last;
-}
-
-void de_emphasis(emphasis_t *state, sample_t *samples, int num)
-{
-	double x, y, y_last, factor, amp;
-	int i;
-
-	y_last = state->d.y_last;
-	factor = state->d.factor;
-	amp = state->d.amp;
-
-	for (i = 0; i < num; i++) {
-		x = *samples;
-
-		/* de-emphasis */
-		y = x + factor * y_last;
-
-		y_last = y;
-
-		*samples++ = amp * y;
-	}
-
-	state->d.y_last = y_last;
-}
-
-/* high pass filter to remove DC and low frequencies */
-void dc_filter(emphasis_t *state, sample_t *samples, int num)
-{
-	iir_process(&state->d.hp, samples, num);
-}
-
diff --git a/src/common/emphasis.h b/src/common/emphasis.h
deleted file mode 100644
index 43d54e6..0000000
--- a/src/common/emphasis.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#include "../libfilter/iir_filter.h"
-
-typedef struct emphasis {
-	struct {
-		iir_filter_t lp;
-		double x_last;
-		double factor;
-		double amp;
-	} p;
-	struct {
-		iir_filter_t hp;
-		double y_last;
-		double factor;
-		double amp;
-	} d;
-} emphasis_t;
-
-#define CUT_OFF_EMPHASIS_DEFAULT 300.0
-
-int init_emphasis(emphasis_t *state, int samplerate, double cut_off);
-void pre_emphasis(emphasis_t *state, sample_t *samples, int num);
-void de_emphasis(emphasis_t *state, sample_t *samples, int num);
-void dc_filter(emphasis_t *state, sample_t *samples, int num);
-
diff --git a/src/common/sender.h b/src/common/sender.h
index 6ec6ad8..09fab06 100644
--- a/src/common/sender.h
+++ b/src/common/sender.h
@@ -5,7 +5,7 @@
 #include "../libwave/wave.h"
 #include "../libsamplerate/samplerate.h"
 #include "../libjitter/jitter.h"
-#include "emphasis.h"
+#include "../libemphasis/emphasis.h"
 #include "display.h"
 
 #define MAX_SENDER	16