X-Git-Url: https://git.sesse.net/?p=c64tapwav;a=blobdiff_plain;f=level.cpp;h=504cf0bbf7549170600674140fff7460c14c85f9;hp=fea59261d3c585d168081bab12edf5a778c352ed;hb=8abf7912f0cc520302437221265484c83bb857e5;hpb=2116cd5829fafa82e23eb328e01e76c876c7b781

diff --git a/level.cpp b/level.cpp
index fea5926..504cf0b 100644
--- a/level.cpp
+++ b/level.cpp
@@ -6,16 +6,7 @@
 #include <vector>
 #include <algorithm>
 
-// The frequency to filter on, in Hertz. Larger values makes the
-// compressor react faster, but if it is too large, you'll
-// ruin the waveforms themselves.
-#define LPFILTER_FREQ 50.0
-
-// The minimum estimated sound level at any given point.
-// If you decrease this, you'll be able to amplify really silent signals
-// by more, but you'll also increase the level of silent (ie. noise-only) segments,
-// possibly caused misdetected pulses in these segments.
-#define MIN_LEVEL 0.05
+#include "filter.h"
 
 // A final scalar to get the audio within approximately the right range.
 // Increase to _lower_ overall volume.
@@ -24,42 +15,7 @@
 // 6dB/oct per round.
 #define FILTER_DEPTH 4
 
-static float a1, a2, b0, b1, b2;
-static float d0, d1;
-
-static void filter_init(float cutoff_radians)
-{
-	float resonance = 1.0f / sqrt(2.0f);
-	float sn = sin(cutoff_radians), cs = cos(cutoff_radians);
-	float alpha = float(sn / (2 * resonance));
-
-	// coefficients for lowpass filter
-        float a0 = 1 + alpha;
-	b0 = (1 - cs) * 0.5f;
-	b1 = 1 - cs;
-	b2 = b0;
-        a1 = -2 * cs;
-        a2 = 1 - alpha;
-
-	b0 /= a0;
-	b1 /= a0;
-	b2 /= a0;
-	a1 /= a0;
-	a2 /= a0;
-
-	// reset filter delays
-	d0 = d1 = 0.0f;
-}
-
-static float filter_update(float in)
-{
-	float out = b0*in + d0;
-	d0 = b1 * in - a1 * out + d1;
-	d1 = b2 * in - a2 * out;
-	return out;
-}
-
-std::vector<float> level_samples(const std::vector<float> &pcm, int sample_rate)
+std::vector<float> level_samples(const std::vector<float> &pcm, float min_level, float lpfilter_freq, int sample_rate)
 {
 	// filter forwards, then backwards (perfect phase filtering)
 	std::vector<float> filtered_samples, refiltered_samples, leveled_samples;
@@ -67,28 +23,28 @@ std::vector<float> level_samples(const std::vector<float> &pcm, int sample_rate)
 	refiltered_samples.resize(pcm.size());
 	leveled_samples.resize(pcm.size());
 
-	filter_init(M_PI * LPFILTER_FREQ / sample_rate);
+	Filter filter = Filter::lpf(2.0 * M_PI * lpfilter_freq / sample_rate);
 	for (unsigned i = 0; i < pcm.size(); ++i) {
-		filtered_samples[i] = filter_update(fabs(pcm[i]));
+		filtered_samples[i] = filter.update(fabs(pcm[i]));
 	}
-	filter_init(M_PI * LPFILTER_FREQ / sample_rate);
+	filter.reset();
 	for (unsigned i = pcm.size(); i --> 0; ) {
-		refiltered_samples[i] = filter_update(filtered_samples[i]);
+		refiltered_samples[i] = filter.update(filtered_samples[i]);
 	}
 
 	for (int i = 1; i < FILTER_DEPTH; ++i) {
-		filter_init(M_PI * LPFILTER_FREQ / sample_rate);
+		filter.reset();
 		for (unsigned i = 0; i < pcm.size(); ++i) {
-			filtered_samples[i] = filter_update(refiltered_samples[i]);
+			filtered_samples[i] = filter.update(refiltered_samples[i]);
 		}
-		filter_init(M_PI * LPFILTER_FREQ / sample_rate);
+		filter.reset();
 		for (unsigned i = pcm.size(); i --> 0; ) {
-			refiltered_samples[i] = filter_update(filtered_samples[i]);
+			refiltered_samples[i] = filter.update(filtered_samples[i]);
 		}
 	}
 
 	for (unsigned i = 0; i < pcm.size(); ++i) {
-		float f = DAMPENING_FACTOR * std::max<float>(refiltered_samples[i], MIN_LEVEL);
+		float f = DAMPENING_FACTOR * std::max<float>(refiltered_samples[i], min_level);
 		leveled_samples[i] = pcm[i] / f;
 	}