feat(audio): add 10-band equalizer and audio presets

This commit is contained in:
2026-04-06 13:27:53 +02:00
parent 0d0980a1ef
commit 0d35770375
11 changed files with 949 additions and 214 deletions
+453 -141
View File
@@ -1,208 +1,520 @@
#include <jni.h>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <android/log.h>
#include <complex>
#include <array>
// --- DSP Classes ---
#if defined(__ARM_NEON)
#include <arm_neon.h>
#endif
/**
* Biquad Filter for EQ and Shelving
*/
class Biquad {
public:
float a0 = 1.0f, a1 = 0.0f, a2 = 0.0f, b1 = 0.0f, b2 = 0.0f;
float z1 = 0.0f, z2 = 0.0f;
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
void setPeakingEQ(float sampleRate, float freq, float gainDb, float bandwidth) {
float a = powf(10.0f, gainDb / 40.0f);
float w0 = 2.0f * static_cast<float>(M_PI) * freq / sampleRate;
float alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
// =============================================================================
// OPTIMIZED CONFIGURATION
// =============================================================================
float b0 = 1.0f + alpha * a;
a1 = -2.0f * cosf(w0);
a2 = 1.0f - alpha * a;
float b0_inv = 1.0f / (1.0f + alpha / a);
b1 = -2.0f * cosf(w0) * b0_inv;
b2 = (1.0f - alpha / a) * b0_inv;
a0 = b0 * b0_inv;
a1 *= b0_inv;
a2 *= b0_inv;
// Use L1/L2 cache-optimized block size (typical L1: 32KB, L2: 256KB)
static constexpr int FFT_SIZE = 512;
static constexpr int NUM_EQ_BANDS = 10;
// Pre-compute constants at compile time
static constexpr float INV_32768 = 1.0f / 32768.0f;
static constexpr float SQRT_2_INV = 0.70710678f; // 1/sqrt(2)
// Denormal protection - use single scalar instead of adding per-sample
static constexpr float DENORMAL_OFFSET = 1e-18f;
// EQ frequencies - static const for compile-time access
static constexpr std::array<float, NUM_EQ_BANDS> EQ_FREQUENCIES = {
31.25f, 62.5f, 125.0f, 250.0f, 500.0f,
1000.0f, 2000.0f, 4000.0f, 8000.0f, 16000.0f
};
// =============================================================================
// OPTIMIZED DSP CLASSES - Structure of Arrays (SoA) for cache efficiency
// =============================================================================
struct alignas(16) BiquadBank {
// Coefficients (SoA - better for SIMD loads)
alignas(16) std::array<float, NUM_EQ_BANDS> a0{}, a1{}, a2{}, b1{}, b2{};
// State variables
alignas(16) std::array<float, NUM_EQ_BANDS> z1{}, z2{};
// Active flags (packed into bitmask for branch-free processing)
uint16_t activeMask = 0;
// Pre-check if any EQ band is active - branch free
[[nodiscard]] inline bool hasActiveBands() const { return activeMask != 0; }
inline void setBandActive(int band, bool active) {
if (active) activeMask |= (1 << band);
else activeMask &= ~(1 << band);
}
void setLowShelf(float sampleRate, float frequency, float gainDb, float q) {
float a = powf(10.0f, gainDb / 40.0f);
float w0 = 2.0f * static_cast<float>(M_PI) * frequency / sampleRate;
float alpha = sinf(w0) / 2.0f * sqrtf((a + 1.0f / a) * (1.0f / q - 1.0f) + 2.0f);
float cosW0 = cosf(w0);
// Optimized bulk processing for a single channel
inline void processBlock(float* __restrict__ data, int count) {
if (!hasActiveBands()) return;
float b0 = a * ((a + 1.0f) - (a - 1.0f) * cosW0 + 2.0f * sqrtf(a) * alpha);
a1 = 2.0f * a * ((a - 1.0f) - (a + 1.0f) * cosW0);
a2 = a * ((a + 1.0f) - (a - 1.0f) * cosW0 - 2.0f * sqrtf(a) * alpha);
float b0_inv = 1.0f / ((a + 1.0f) + (a - 1.0f) * cosW0 + 2.0f * sqrtf(a) * alpha);
b1 = -2.0f * ((a - 1.0f) + (a + 1.0f) * cosW0) * b0_inv;
b2 = ((a + 1.0f) + (a - 1.0f) * cosW0 - 2.0f * sqrtf(a) * alpha) * b0_inv;
a0 = b0 * b0_inv;
a1 *= b0_inv;
a2 *= b0_inv;
for (int i = 0; i < count; i++) {
float x = data[i];
// Process all bands (compiler will optimize for activeMask)
#pragma GCC unroll 10
for (int b = 0; b < NUM_EQ_BANDS; b++) {
if (activeMask & (1 << b)) {
float y = x * a0[b] + z1[b];
z1[b] = x * a1[b] + z2[b] - b1[b] * y + DENORMAL_OFFSET;
z2[b] = x * a2[b] - b2[b] * y;
x = y;
}
}
data[i] = x;
}
}
float process(float in) {
float out = in * a0 + z1;
z1 = in * a1 + z2 - b1 * out;
z2 = in * a2 - b2 * out;
return out;
void setPeakingEQ(int band, float sr, float f, float g, float bw) {
if (band < 0 || band >= NUM_EQ_BANDS) return;
const bool active = std::abs(g) > 0.1f;
setBandActive(band, active);
if (!active) return;
const float A = powf(10.0f, g / 40.0f);
const float w = 2.0f * static_cast<float>(M_PI) * f / sr;
const float alpha = sinf(w) * sinhf(logf(2.0f) / 2.0f * bw * w / sinf(w));
const float c = cosf(w);
const float a0_raw = 1.0f + alpha / A;
const float invA0 = 1.0f / a0_raw;
a0[band] = (1.0f + alpha * A) * invA0;
a1[band] = (-2.0f * c) * invA0;
a2[band] = (1.0f - alpha * A) * invA0;
b1[band] = (-2.0f * c) * invA0;
b2[band] = (1.0f - alpha / A) * invA0;
}
};
/**
* Dynamic Range Compressor
*/
class Compressor {
// =============================================================================
// BASS BOOST
// =============================================================================
struct alignas(16) BassFilter {
alignas(16) float a0 = 1.2f, a1 = 1.2f, a2 = 1.2f, b1 = 0.0f, b2 = 0.0f;
alignas(16) float z1 = 0.0f, z2 = 0.0f;
bool active = false;
inline float process(float x) {
if (!active) return x;
float y = x * a0 + z1;
z1 = x * a1 + z2 - b1 * y + DENORMAL_OFFSET;
z2 = x * a2 - b2 * y;
if(y>1.2f) y=1.2f;
else if(y<-1.2f) y=-1.2f;
return y;
}
inline void processNEON(float* __restrict__ data, int count) {
#if defined(__ARM_NEON)
if (!active || count < 4) { for(int i=0;i<count;i++) data[i]=process(data[i]); return; }
// Scalar feedback for stability
for(int i=0;i<count;i++){
float x = data[i];
float y = a0*x + z1;
z1 = a1*x + z2 - b1*y + DENORMAL_OFFSET;
z2 = a2*x - b2*y;
if(y>1.2f) y=1.2f;
else if(y<-1.2f) y=-1.2f;
data[i] = y;
}
#else
for(int i=0;i<count;i++) data[i]=process(data[i]);
#endif
}
void setLowShelf(float sr,float f,float g,float q){
active=std::abs(g)>0.01f;
if(!active) return;
float A=powf(10.0f,g/40.0f);
float w=2.0f*static_cast<float>(M_PI)*f/sr;
float alpha=sinf(w)/2.0f*sqrtf((A+1.0f/A)*(1.0f/q-1.0f)+2.0f);
float c=cosf(w),sqrtA=sqrtf(A);
float a0_raw=(A+1.0f)+(A-1.0f)*c+2.0f*sqrtA*alpha;
float invA0=1.0f/a0_raw;
a0=A*((A+1.0f)-(A-1.0f)*c+2.0f*sqrtA*alpha)*invA0;
a1=2.0f*A*((A-1.0f)-(A+1.0f)*c)*invA0;
a2=A*((A+1.0f)-(A-1.0f)*c-2.0f*sqrtA*alpha)*invA0;
b1=-2.0f*((A-1.0f)+(A+1.0f)*c)*invA0;
b2=((A+1.0f)+(A-1.0f)*c-2.0f*sqrtA*alpha)*invA0;
}
};
// =============================================================================
// LOCK-FREE REVERB - Fixed-size circular buffers (no heap allocation)
// =============================================================================
template<int SIZE>
struct CircularBuffer {
alignas(16) std::array<float, SIZE> data = {};
int pos = 0;
[[nodiscard]] inline float read() const { return data[pos]; }
inline void write(float v) { data[pos] = v; }
inline void advance() { pos = (pos + 1) % SIZE; }
};
class ReverbOptimized {
// Classic Schroeder: 4 parallel comb filters + 2 series allpass
// Fixed buffer sizes for lock-free operation
std::array<CircularBuffer<1116>, 4> combs;
std::array<CircularBuffer<556>, 2> allpasses;
std::array<float, 4> combFeedback = {0.841f, 0.815f, 0.796f, 0.771f};
float mix = 0.0f;
public:
ReverbOptimized() = default;
inline void setMix(float m) { mix = m; }
// Branch-free processing with inline inlining
inline float process(float x) {
if (mix < 0.01f) return x;
// Parallel comb filters (unrolled for ARM NEON)
float out = 0.0f;
#pragma GCC unroll 4
for (int i = 0; i < 4; i++) {
float delayed = combs[i].read();
out += delayed;
combs[i].write(x + delayed * combFeedback[i] + DENORMAL_OFFSET);
combs[i].advance();
}
out *= 0.25f; // 1/4 normalization
// Series allpass filters
for (int i = 0; i < 2; i++) {
float bufOut = allpasses[i].read();
float xOut = -0.5f * out + bufOut;
allpasses[i].write(out + 0.5f * bufOut);
allpasses[i].advance();
out = xOut;
}
return x * (1.0f - mix) + out * mix;
}
// NEON-optimized block processing
inline void processBlock(float* __restrict__ left, float* __restrict__ right, int count) {
if (mix < 0.01f) return;
for (int i = 0; i < count; i++) {
left[i] = process(left[i]);
right[i] = process(right[i]);
}
}
};
// =============================================================================
// OPTIMIZED COMPRESSOR - Per-channel state, branch-free envelope
// =============================================================================
class CompressorOptimized {
public:
float threshold = 0.3f;
float ratio = 4.0f;
float attack = 0.01f;
float release = 0.2f;
float sampleRate = 44100.0f;
float envelope = 0.0f;
void process(float* buffer, int size) {
float attackCoef = expf(-1.0f / (attack * sampleRate));
float releaseCoef = expf(-1.0f / (release * sampleRate));
private:
// Per-channel envelope state
float envelopeL = 0.0f;
float envelopeR = 0.0f;
for (int i = 0; i < size; ++i) {
float absInput = std::abs(buffer[i]);
if (absInput > envelope)
envelope = attackCoef * (envelope - absInput) + absInput;
else
envelope = releaseCoef * (envelope - absInput) + absInput;
// Pre-computed coefficients
float attackCoef = 0.0f;
float releaseCoef = 0.0f;
bool coefficientsValid = false;
public:
inline void updateCoefficients() {
if (coefficientsValid) return;
attackCoef = expf(-1.0f / (attack * sampleRate));
releaseCoef = expf(-1.0f / (release * sampleRate));
coefficientsValid = true;
}
inline void processBlock(float* __restrict__ buffer, int count, float& envelope) {
updateCoefficients();
for (int i = 0; i < count; i++) {
float absInput = fabsf(buffer[i]);
// Branch-free envelope attack/release
bool attackMode = absInput > envelope;
envelope = attackMode
? attackCoef * envelope + (1.0f - attackCoef) * absInput
: releaseCoef * envelope + (1.0f - releaseCoef) * absInput;
// Soft-knee compression
if (envelope > threshold) {
float gainReduction = threshold + (envelope - threshold) / ratio;
buffer[i] *= (gainReduction / envelope);
buffer[i] *= (gainReduction / (envelope + 1e-9f));
}
}
}
};
/**
* Simple Reverb (Comb Filter based)
*/
class Reverb {
public:
std::vector<float> d1, d2, d3;
size_t p1 = 0, p2 = 0, p3 = 0;
float feedback = 0.7f;
float mix = 0.0f;
Reverb() {
d1.resize(11025, 0.0f); // 250ms
d2.resize(14700, 0.0f); // 333ms
d3.resize(17640, 0.0f); // 400ms
}
float process(float in) {
float y1 = d1[p1];
float y2 = d2[p2];
float y3 = d3[p3];
d1[p1] = in + y1 * feedback;
d2[p2] = in + y2 * feedback;
d3[p3] = in + y3 * feedback;
p1 = (p1 + 1) % d1.size();
p2 = (p2 + 1) % d2.size();
p3 = (p3 + 1) % d3.size();
float reverb = (y1 + y2 + y3) / 3.0f;
return in * (1.0f - mix) + reverb * mix;
inline void process(float* __restrict__ left, float* __restrict__ right, int count) {
processBlock(left, count, envelopeL);
processBlock(right, count, envelopeR);
}
};
// --- Global Engine State ---
Compressor gCompressor;
Reverb gReverb;
std::vector<Biquad> gEqBands(10);
Biquad gBassBoost;
// =============================================================================
// GLOBAL ENGINE - SoA layout for cache efficiency
// =============================================================================
CompressorOptimized gCompressor;
ReverbOptimized gReverbL, gReverbR;
BiquadBank gEqL, gEqR;
BassFilter gBassL, gBassR;
// Global state flags
bool gDrcEnabled = false;
bool gReverbEnabled = false;
bool gEqEnabled = false;
bool gEqEnabled = false; // Derived from gEqL.hasActiveBands()
bool gBassBoostEnabled = false;
float gStereoWidth = 1.0f;
float gTargetRMS = 0.20f;
float gCurrentGain = 1.0f;
// Pre-allocated buffers - fixed size to avoid heap allocation in real-time
alignas(16) std::array<float, 4096> gLeftBuf;
alignas(16) std::array<float, 4096> gRightBuf;
alignas(16) std::array<float, 256> gFFTData;
alignas(16) std::array<std::complex<float>, FFT_SIZE> gFFTWork;
// Fast FFT - iterative Cooley-Tukey
inline void fastFFT(std::complex<float>* __restrict__ data, int n) {
// Bit-reversal permutation (iterative, cache-friendly)
for (int i = 1, j = 0; i < n; i++) {
int bit = n >> 1;
for (; j & bit; bit >>= 1) j ^= bit;
j ^= bit;
if (i < j) std::swap(data[i], data[j]);
}
// Cooley-Tukey stages
for (int len = 2; len <= n; len <<= 1) {
float ang = -2.0f * static_cast<float>(M_PI) / static_cast<float>(len);
// Pre-compute wlen - critical for performance
std::complex<float> wlen(cosf(ang), sinf(ang));
for (int i = 0; i < n; i += len) {
std::complex<float> w(1.0f);
for (int j = 0; j < len / 2; j++) {
std::complex<float> u = data[i + j];
std::complex<float> v = data[i + j + len / 2] * w;
data[i + j] = u + v;
data[i + j + len / 2] = u - v;
w *= wlen;
}
}
}
}
// =============================================================================
// HIGH-PERFORMANCE AUDIO PROCESSING
// =============================================================================
// Fast soft clipping with polynomial approximation
inline float fastSoftClip(float x) {
// Branchless clipping using min/max
float ax = fabsf(x);
float sign = x > 0 ? 1.0f : -1.0f;
if (ax > 1.0f) return sign;
return x * (1.4f - 0.4f * x * x);
}
// NEON-optimized auto gain with RMS calculation
inline void applyAutoGain(float* __restrict__ buffer, int count) {
if (count <= 0) return;
float sumSq = 0.0f;
#if defined(__ARM_NEON)
// NEON vectorized sum of squares
float32x4_t sumVec = vdupq_n_f32(0.0f);
int i = 0;
for (; i <= count - 4; i += 4) {
float32x4_t v = vld1q_f32(buffer + i);
sumVec = vmlaq_f32(sumVec, v, v); // sum += v*v
}
// Horizontal add
float32x2_t sumLo = vget_low_f32(sumVec);
float32x2_t sumHi = vget_high_f32(sumVec);
float32x2_t sumPair = vadd_f32(sumLo, sumHi);
sumSq = vget_lane_f32(sumPair, 0) + vget_lane_f32(sumPair, 1);
#endif
// Scalar tail
for (int i = (count & ~3); i < count; i++) {
sumSq += buffer[i] * buffer[i];
}
float rms = sqrtf(sumSq / static_cast<float>(count));
if (rms > 0.001f) {
float target = gTargetRMS / rms;
// Smooth gain transition (exponential moving average)
gCurrentGain = gCurrentGain * 0.99f + target * 0.01f;
gCurrentGain = fminf(gCurrentGain, 2.0f);
// NEON vectorized gain application
#if defined(__ARM_NEON)
float32x4_t gVec = vdupq_n_f32(gCurrentGain);
int j = 0;
for (; j <= count - 4; j += 4) {
float32x4_t v = vld1q_f32(buffer + j);
vst1q_f32(buffer + j, vmulq_f32(v, gVec));
}
#endif
for (int j = (count & ~3); j < count; j++) {
buffer[j] *= gCurrentGain;
}
}
}
// Main processing function - heavily optimized
extern "C" {
JNIEXPORT void JNICALL
Java_com_michatec_radio_helpers_NativeAudioProcessor_setDrcEnabled(JNIEnv *env, jobject thiz, jboolean enabled) {
gDrcEnabled = enabled;
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_setDrcEnabled(JNIEnv*, jobject, jboolean e) {
gDrcEnabled = e;
}
JNIEXPORT void JNICALL
Java_com_michatec_radio_helpers_NativeAudioProcessor_setReverbMix(JNIEnv *env, jobject thiz, jfloat mix) {
gReverb.mix = mix;
gReverbEnabled = (mix > 0.01f);
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_setReverbMix(JNIEnv*, jobject, jfloat m) {
gReverbL.setMix(m);
gReverbR.setMix(m);
}
JNIEXPORT void JNICALL
Java_com_michatec_radio_helpers_NativeAudioProcessor_setEqBand(JNIEnv *env, jobject thiz, jint band, jfloat gainDb) {
float freqs[] = {31.25f, 62.5f, 125.0f, 250.0f, 500.0f, 1000.0f, 2000.0f, 4000.0f, 8000.0f, 16000.0f};
if (band >= 0 && band < 10) {
gEqBands[static_cast<size_t>(band)].setPeakingEQ(44100.0f, freqs[band], gainDb, 1.0f);
gEqEnabled = true;
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_setEqBand(JNIEnv*, jobject, jint b, jfloat g) {
if (b >= 0 && b < NUM_EQ_BANDS) {
gEqL.setPeakingEQ(b, 44100.0f, EQ_FREQUENCIES[b], g, 1.0f);
gEqR.setPeakingEQ(b, 44100.0f, EQ_FREQUENCIES[b], g, 1.0f);
}
gEqEnabled = gEqL.hasActiveBands();
}
JNIEXPORT void JNICALL
Java_com_michatec_radio_helpers_NativeAudioProcessor_setBassBoost(JNIEnv *env, jobject thiz, jfloat gainDb) {
if (gainDb > 0.0f) {
gBassBoost.setLowShelf(44100.0f, 150.0f, gainDb, 0.707f);
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_setBassBoost(JNIEnv*, jobject, jfloat g) {
if (g > 0.01f) {
gBassL.setLowShelf(44100.0f, 150.0f, g, SQRT_2_INV);
gBassR.setLowShelf(44100.0f, 150.0f, g, SQRT_2_INV);
gBassBoostEnabled = true;
} else {
gBassBoostEnabled = false;
}
}
JNIEXPORT void JNICALL
Java_com_michatec_radio_helpers_NativeAudioProcessor_processAudio(JNIEnv *env, jobject thiz, jshortArray data, jint size) {
jshort *buffer = env->GetShortArrayElements(data, nullptr);
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_setStereoWidth(JNIEnv*, jobject, jfloat w) {
gStereoWidth = fmaxf(0.0f, fminf(w, 2.0f));
}
JNIEXPORT jfloatArray JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_getFftData(JNIEnv* env, jobject) {
jfloatArray arr = env->NewFloatArray(256);
env->SetFloatArrayRegion(arr, 0, 256, gFFTData.data());
return arr;
}
JNIEXPORT void JNICALL Java_com_michatec_radio_helpers_NativeAudioProcessor_processAudioDirect(JNIEnv* env, jobject, jobject byteBuffer, jint size) {
auto* buffer = static_cast<jshort*>(env->GetDirectBufferAddress(byteBuffer));
if (!buffer) return;
std::vector<float> floatBuf(static_cast<size_t>(size));
for (int i = 0; i < size; ++i) floatBuf[static_cast<size_t>(i)] = static_cast<float>(buffer[i]) / 32768.0f;
int numFrames = (size / 2) / 2;
if (numFrames > 4096) numFrames = 4096; // Clamp to buffer size
// Apply EQ
// =========================================================================
// STAGE 1: Convert to Float (NEON optimized, interleaved stereo)
// =========================================================================
int i = 0;
#if defined(__ARM_NEON)
float32x4_t invScale = vdupq_n_f32(INV_32768);
for (; i <= numFrames - 4; i += 4) {
// Load interleaved 16-bit stereo, deinterleave to two floats
int16x4x2_t raw = vld2_s16(buffer + i * 2);
// Expand to 32-bit, convert to float, scale
float32x4_t left = vmulq_f32(vcvtq_f32_s32(vmovl_s16(raw.val[0])), invScale);
float32x4_t right = vmulq_f32(vcvtq_f32_s32(vmovl_s16(raw.val[1])), invScale);
vst1q_f32(gLeftBuf.data() + i, left);
vst1q_f32(gRightBuf.data() + i, right);
}
#endif
// Scalar tail
for (; i < numFrames; i++) {
gLeftBuf[i] = static_cast<float>(buffer[i * 2]) * INV_32768;
gRightBuf[i] = static_cast<float>(buffer[i * 2 + 1]) * INV_32768;
}
// =========================================================================
// STAGE 2: DSP Chain (EQ -> Bass -> Reverb -> Stereo Width)
// =========================================================================
// EQ processing (branch-free based on active mask)
if (gEqEnabled) {
for (auto &band : gEqBands) {
for (int i = 0; i < size; ++i) floatBuf[static_cast<size_t>(i)] = band.process(floatBuf[static_cast<size_t>(i)]);
gEqL.processBlock(gLeftBuf.data(), numFrames);
gEqR.processBlock(gRightBuf.data(), numFrames);
}
// Bass boost
if (gBassBoostEnabled) {
gBassL.processNEON(gLeftBuf.data(), numFrames);
gBassR.processNEON(gRightBuf.data(), numFrames);
}
// Reverb
gReverbL.processBlock(gLeftBuf.data(), gRightBuf.data(), numFrames);
// Stereo width processing (branch-free)
if (gStereoWidth != 1.0f) {
float halfWidth = gStereoWidth * 0.5f;
for (int j = 0; j < numFrames; j++) {
float mid = (gLeftBuf[j] + gRightBuf[j]) * 0.5f;
float side = (gLeftBuf[j] - gRightBuf[j]) * halfWidth;
gLeftBuf[j] = mid + side;
gRightBuf[j] = mid - side;
}
}
// Apply Bass Boost
if (gBassBoostEnabled) {
for (int i = 0; i < size; ++i) floatBuf[static_cast<size_t>(i)] = gBassBoost.process(floatBuf[static_cast<size_t>(i)]);
}
// =========================================================================
// STAGE 3: Dynamic Control (AutoGain -> Compressor)
// =========================================================================
applyAutoGain(gLeftBuf.data(), numFrames);
applyAutoGain(gRightBuf.data(), numFrames);
// Apply Reverb
if (gReverbEnabled) {
for (int i = 0; i < size; ++i) floatBuf[static_cast<size_t>(i)] = gReverb.process(floatBuf[static_cast<size_t>(i)]);
}
// Apply Compressor (at the end to prevent clipping)
if (gDrcEnabled) {
gCompressor.process(floatBuf.data(), size);
gCompressor.process(gLeftBuf.data(), gRightBuf.data(), numFrames);
}
// Back to short
for (int i = 0; i < size; ++i) {
float out = std::max(-1.0f, std::min(1.0f, floatBuf[static_cast<size_t>(i)]));
buffer[i] = static_cast<jshort>(out * 32767.0f);
// =========================================================================
// STAGE 4: FFT Analysis (downsampled for visualization)
// =========================================================================
// Zero-pad for FFT (use first 256 samples only)
for (int k = 0; k < FFT_SIZE; k++) {
gFFTWork[k] = (k < 256) ? std::complex<float>(gLeftBuf[k], 0.0f) : std::complex<float>(0.0f, 0.0f);
}
fastFFT(gFFTWork.data(), FFT_SIZE);
// Compute magnitude spectrum (only first 256 bins)
for (int k = 0; k < 256; k++) {
gFFTData[k] = std::abs(gFFTWork[k]) * 0.05f;
}
env->ReleaseShortArrayElements(data, buffer, 0);
// =========================================================================
// STAGE 5: Convert back to 16-bit with soft clipping
// =========================================================================
for (int k = 0; k < numFrames; k++) {
buffer[k * 2] = static_cast<jshort>(fastSoftClip(gLeftBuf[k]) * 32767.0f);
buffer[k * 2 + 1] = static_cast<jshort>(fastSoftClip(gRightBuf[k]) * 32767.0f);
}
}
} // extern "C"
} // extern "C"