add a-law companding functions

companding/alaw.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <cmath>
+
+namespace trnr {
+
+constexpr float A_LAW_A = 87.6f;
+
+inline float alaw_encode(float input)
+{
+	float sign = (input >= 0.0f) ? 1.0f : -1.0f;
+	float abs_sample = std::fabs(input);
+
+	float output;
+	if (abs_sample < (1.0f / A_LAW_A)) {
+		output = sign * (A_LAW_A * abs_sample) / (1.0f + std::log(A_LAW_A));
+	} else {
+		output = sign * (1.0f + std::log(A_LAW_A * abs_sample)) / (1.0f + std::log(A_LAW_A));
+	}
+
+	return output;
+}
+
+inline float alaw_decode(float input)
+{
+	float sign = (input >= 0.0f) ? 1.0f : -1.0f;
+	float abs_comp = std::fabs(input);
+
+	float sample;
+	if (abs_comp < (1.0f / (1.0f + std::log(A_LAW_A)))) {
+		sample = sign * (abs_comp * (1.0f + std::log(A_LAW_A))) / A_LAW_A;
+	} else {
+		sample = sign * std::exp(abs_comp * (1.0f + std::log(A_LAW_A)) - 1.0f) / A_LAW_A;
+	}
+
+	return sample;
+}
+} // namespace trnr

companding/mulaw.h

@@ -1,48 +0,0 @@
-#pragma once
-#include <cstdint>
-
-namespace trnr {
-// mulaw companding based on code by Emilie Gillet / Mutable Instruments
-class mulaw {
-public:
-	int8_t encode_samples(int16_t pcm_val)
-	{
-		int16_t mask;
-		int16_t seg;
-		uint8_t uval;
-		pcm_val = pcm_val >> 2;
-		if (pcm_val < 0) {
-			pcm_val = -pcm_val;
-			mask = 0x7f;
-		} else {
-			mask = 0xff;
-		}
-		if (pcm_val > 8159) pcm_val = 8159;
-		pcm_val += (0x84 >> 2);
-
-		if (pcm_val <= 0x3f) seg = 0;
-		else if (pcm_val <= 0x7f) seg = 1;
-		else if (pcm_val <= 0xff) seg = 2;
-		else if (pcm_val <= 0x1ff) seg = 3;
-		else if (pcm_val <= 0x3ff) seg = 4;
-		else if (pcm_val <= 0x7ff) seg = 5;
-		else if (pcm_val <= 0xfff) seg = 6;
-		else if (pcm_val <= 0x1fff) seg = 7;
-		else seg = 8;
-		if (seg >= 8) return static_cast<uint8_t>(0x7f ^ mask);
-		else {
-			uval = static_cast<uint8_t>((seg << 4) | ((pcm_val >> (seg + 1)) & 0x0f));
-			return (uval ^ mask);
-		}
-	}
-
-	int16_t decode_samples(uint8_t u_val)
-	{
-		int16_t t;
-		u_val = ~u_val;
-		t = ((u_val & 0xf) << 3) + 0x84;
-		t <<= ((unsigned)u_val & 0x70) >> 4;
-		return ((u_val & 0x80) ? (0x84 - t) : (t - 0x84));
-	}
-};
-} // namespace trnr

companding/ulaw.h

@@ -1,108 +0,0 @@
-#pragma once
-#include <cmath>
-#include <cstdint>
-#include <stdlib.h>
-
-namespace trnr {
-// ulaw compansion based on code by Chris Johnson
-class ulaw {
-public:
-	ulaw()
-	{
-		fpd_l = 1.0;
-		while (fpd_l < 16386) fpd_l = rand() * UINT32_MAX;
-		fpd_r = 1.0;
-		while (fpd_r < 16386) fpd_r = rand() * UINT32_MAX;
-	}
-
-	void encode_samples(double& input_sample_l, double& input_sample_r)
-	{
-
-		// ulaw encoding
-		static int noisesource_l = 0;
-		static int noisesource_r = 850010;
-		int residue;
-		double applyresidue;
-
-		noisesource_l = noisesource_l % 1700021;
-		noisesource_l++;
-		residue = noisesource_l * noisesource_l;
-		residue = residue % 170003;
-		residue *= residue;
-		residue = residue % 17011;
-		residue *= residue;
-		residue = residue % 1709;
-		residue *= residue;
-		residue = residue % 173;
-		residue *= residue;
-		residue = residue % 17;
-		applyresidue = residue;
-		applyresidue *= 0.00000001;
-		applyresidue *= 0.00000001;
-		input_sample_l += applyresidue;
-		if (input_sample_l < 1.2e-38 && -input_sample_l < 1.2e-38) { input_sample_l -= applyresidue; }
-
-		noisesource_r = noisesource_r % 1700021;
-		noisesource_r++;
-		residue = noisesource_r * noisesource_r;
-		residue = residue % 170003;
-		residue *= residue;
-		residue = residue % 17011;
-		residue *= residue;
-		residue = residue % 1709;
-		residue *= residue;
-		residue = residue % 173;
-		residue *= residue;
-		residue = residue % 17;
-		applyresidue = residue;
-		applyresidue *= 0.00000001;
-		applyresidue *= 0.00000001;
-		input_sample_r += applyresidue;
-		if (input_sample_r < 1.2e-38 && -input_sample_r < 1.2e-38) { input_sample_r -= applyresidue; }
-
-		if (input_sample_l > 1.0) input_sample_l = 1.0;
-		if (input_sample_l < -1.0) input_sample_l = -1.0;
-
-		if (input_sample_r > 1.0) input_sample_r = 1.0;
-		if (input_sample_r < -1.0) input_sample_r = -1.0;
-
-		if (input_sample_l > 0) input_sample_l = log(1.0 + (255 * fabs(input_sample_l))) / log(256);
-		if (input_sample_l < 0) input_sample_l = -log(1.0 + (255 * fabs(input_sample_l))) / log(256);
-
-		if (input_sample_r > 0) input_sample_r = log(1.0 + (255 * fabs(input_sample_r))) / log(256);
-		if (input_sample_r < 0) input_sample_r = -log(1.0 + (255 * fabs(input_sample_r))) / log(256);
-	}
-
-	void decode_samples(double& input_sample_l, double& input_sample_r)
-	{
-
-		// ulaw decoding
-		if (fabs(input_sample_l) < 1.18e-23) input_sample_l = fpd_l * 1.18e-17;
-		if (fabs(input_sample_r) < 1.18e-23) input_sample_r = fpd_r * 1.18e-17;
-
-		if (input_sample_l > 1.0) input_sample_l = 1.0;
-		if (input_sample_l < -1.0) input_sample_l = -1.0;
-
-		if (input_sample_r > 1.0) input_sample_r = 1.0;
-		if (input_sample_r < -1.0) input_sample_r = -1.0;
-
-		if (input_sample_l > 0) input_sample_l = (pow(256, fabs(input_sample_l)) - 1.0) / 255;
-		if (input_sample_l < 0) input_sample_l = -(pow(256, fabs(input_sample_l)) - 1.0) / 255;
-
-		if (input_sample_r > 0) input_sample_r = (pow(256, fabs(input_sample_r)) - 1.0) / 255;
-		if (input_sample_r < 0) input_sample_r = -(pow(256, fabs(input_sample_r)) - 1.0) / 255;
-
-		// 64 bit stereo floating point dither
-		fpd_l ^= fpd_l << 13;
-		fpd_l ^= fpd_l >> 17;
-		fpd_l ^= fpd_l << 5;
-		fpd_r ^= fpd_r << 13;
-		fpd_r ^= fpd_r >> 17;
-		fpd_r ^= fpd_r << 5;
-	}
-
-private:
-	uint32_t fpd_l;
-	uint32_t fpd_r;
-};
-} // namespace trnr