voice-cat/tests/test_opus_codec.cpp

/*
 * test_opus_codec — Opus encode/decode round-trip, PLC, energy check.
 *
 * Requires VOICECAT_HAS_OPUS (m1-dev and m2-dev presets).
 */
#include <cmath>
#include <cstdio>
#include <cstring>
#include <vector>

#include "codec/opus_codec.h"

namespace vc_codec = voicecat::codec;

static int g_failures = 0;

#define CHECK(cond) \
    do { if (!(cond)) { \
        std::printf("FAIL [%s:%d]: %s\n", __FILE__, __LINE__, #cond); \
        ++g_failures; \
    }} while (0)

#ifndef VOICECAT_HAS_OPUS

int main() {
    std::printf("opus_codec: VOICECAT_HAS_OPUS not defined — skipped\n");
    return 0;
}

#else

static constexpr int kSampleRate  = 48000;
static constexpr int kFrameMs     = 20;
static constexpr int kFrameSamples = kSampleRate / 1000 * kFrameMs;  // 960

// Generate one frame of 440 Hz sine wave at 16-bit mono, 48 kHz.
static std::vector<int16_t> make_sine_frame(int samples, float freq = 440.0f) {
    std::vector<int16_t> pcm(samples);
    for (int i = 0; i < samples; ++i) {
        float t = static_cast<float>(i) / kSampleRate;
        pcm[i] = static_cast<int16_t>(std::sin(2.0f * 3.14159265f * freq * t) * 16000.0f);
    }
    return pcm;
}

// Compute RMS energy of a PCM buffer.
static double rms(const int16_t* pcm, int n) {
    double sum = 0.0;
    for (int i = 0; i < n; ++i) sum += static_cast<double>(pcm[i]) * pcm[i];
    return std::sqrt(sum / n);
}

static void test_encode_decode_round_trip() {
    vc_codec::OpusParams p;
    p.sample_rate = kSampleRate;
    p.frame_ms    = kFrameMs;
    p.fec         = true;

    vc_codec::OpusEncoder enc;
    vc_codec::OpusDecoder dec;
    CHECK(enc.init(p));
    CHECK(dec.init(p));

    auto src = make_sine_frame(kFrameSamples);

    uint8_t encoded[4000];
    int enc_bytes = enc.encode(src.data(), kFrameSamples, encoded, sizeof(encoded));
    CHECK(enc_bytes > 0);
    CHECK(enc_bytes < 1000);  // Opus at 24 kbps/20 ms ≈ 60 bytes, well under 1000

    std::vector<int16_t> decoded(kFrameSamples);
    int dec_samples = dec.decode(encoded, enc_bytes, decoded.data(), kFrameSamples);
    CHECK(dec_samples == kFrameSamples);

    // Energy check: decoded RMS should be within 3 dB of original (Opus is lossy).
    double rms_src = rms(src.data(), kFrameSamples);
    double rms_dec = rms(decoded.data(), dec_samples);
    CHECK(rms_src > 0.0);
    CHECK(rms_dec > 0.0);
    double ratio_db = 20.0 * std::log10(rms_dec / rms_src);
    std::printf("  opus round-trip: enc_bytes=%d dec_samples=%d rms_ratio_db=%.1f\n",
                enc_bytes, dec_samples, ratio_db);
    CHECK(std::abs(ratio_db) < 3.0);

    enc.destroy();
    dec.destroy();
}

static void test_plc() {
    vc_codec::OpusParams p;
    p.sample_rate = kSampleRate;
    p.frame_ms    = kFrameMs;

    vc_codec::OpusDecoder dec;
    CHECK(dec.init(p));

    // First send a real packet so the decoder has state for PLC.
    vc_codec::OpusEncoder enc;
    CHECK(enc.init(p));
    auto src = make_sine_frame(kFrameSamples);
    uint8_t encoded[4000];
    int enc_bytes = enc.encode(src.data(), kFrameSamples, encoded, sizeof(encoded));
    CHECK(enc_bytes > 0);

    std::vector<int16_t> real_out(kFrameSamples);
    int r = dec.decode(encoded, enc_bytes, real_out.data(), kFrameSamples);
    CHECK(r == kFrameSamples);

    // Now simulate packet loss with PLC (nullptr, len=0).
    std::vector<int16_t> plc_out(kFrameSamples, 0);
    int plc_samples = dec.decode(nullptr, 0, plc_out.data(), kFrameSamples);
    CHECK(plc_samples == kFrameSamples);

    // PLC output should not be silent (Opus extrapolates from previous frame).
    double plc_rms = rms(plc_out.data(), kFrameSamples);
    std::printf("  plc_rms=%.1f (should be > 0)\n", plc_rms);
    CHECK(plc_rms > 0.0);

    enc.destroy();
    dec.destroy();
}

static void test_frame_samples_helper() {
    vc_codec::OpusParams p;
    p.sample_rate = 48000;
    p.frame_ms    = 20;
    CHECK(vc_codec::opus_frame_samples(p) == 960);

    p.frame_ms = 10;
    CHECK(vc_codec::opus_frame_samples(p) == 480);

    p.frame_ms = 40;
    CHECK(vc_codec::opus_frame_samples(p) == 1920);
}

int main() {
    test_frame_samples_helper();
    test_encode_decode_round_trip();
    test_plc();

    if (g_failures == 0) {
        std::printf("opus_codec: all tests passed\n");
        return 0;
    }
    std::printf("opus_codec: %d test(s) FAILED\n", g_failures);
    return 1;
}

#endif  // VOICECAT_HAS_OPUS