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// Tests the wav->spec->wav roundtrip SNR.
// Generates a sine wave, runs OLA encode then OLA decode,
// and asserts the reconstruction SNR exceeds the threshold.
#include "audio/ola.h"
#include <assert.h>
#include <cmath>
#include <cstdio>
#include <vector>
static const int SAMPLE_RATE = 32000;
static const float PI = 3.14159265358979323846f;
static float compute_snr_db(const std::vector<float>& ref,
const std::vector<float>& out,
int skip_samples) {
const int n = (int)std::min(ref.size(), out.size());
double sig = 0.0, noise = 0.0;
for (int i = skip_samples; i < n; ++i) {
sig += (double)ref[i] * ref[i];
double e = ref[i] - out[i];
noise += e * e;
}
if (noise < 1e-30) return 999.0f;
return 10.0f * (float)log10(sig / noise);
}
int main() {
printf("Running WAV roundtrip test...\n");
// 1-second 440 Hz sine at 32 kHz
const int n_samples = SAMPLE_RATE;
std::vector<float> input(n_samples);
for (int i = 0; i < n_samples; ++i)
input[i] = 0.5f * sinf(2.0f * PI * 440.0f * i / SAMPLE_RATE);
// Encode
const int num_frames = ola_num_frames(n_samples);
std::vector<float> spec(num_frames * DCT_SIZE);
ola_encode(input.data(), n_samples, spec.data(), num_frames);
// Decode
std::vector<float> output(num_frames * OLA_HOP_SIZE);
ola_decode(spec.data(), num_frames, output.data());
// SNR — skip first DCT_SIZE samples (ramp-up transient)
const float snr = compute_snr_db(input, output, DCT_SIZE);
printf("Roundtrip SNR: %.1f dB (frames=%d, out_samples=%zu)\n",
snr, num_frames, output.size());
const float MIN_SNR_DB = 30.0f;
if (snr < MIN_SNR_DB) {
printf("FAIL: SNR %.1f dB < %.0f dB threshold\n", snr, MIN_SNR_DB);
return 1;
}
printf("PASS\n");
return 0;
}
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