외부 사운드 파일 없는 C 언어 절차적 파형 합성 및 44바이트 WAV 헤더 직렬화Procedural Audio Waveform Synthesis and 44-Byte WAV Header Serialization in C

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define SAMPLE_RATE 44100
#define TWO_PI      6.28318530718f

#pragma pack(push, 1)
typedef struct {
    char     riff_id[4];      // "RIFF"
    uint32_t file_size;       // 36 + data_size
    char     wave_id[4];      // "WAVE"
    char     fmt_id[4];       // "fmt "
    uint32_t fmt_size;        // 16 (PCM)
    uint16_t audio_format;    // 1 (Linear Quantization)
    uint16_t num_channels;    // 1 (Mono)
    uint32_t sample_rate;     // 44100
    uint32_t byte_rate;       // sample_rate * num_channels * 2
    uint16_t block_align;     // num_channels * 2
    uint16_t bits_per_sample; // 16
    char     data_id[4];      // "data"
    uint32_t data_size;       // num_samples * 2
} WavHeader44;
#pragma pack(pop)

// 메모리 버퍼에 44바이트 WAV 헤더 + 16비트 PCM 레이저/점프 효과음 생성
uint8_t* BuildProceduralSfxWav(float duration_sec, float start_hz, float end_hz, size_t *out_bytes) {
    uint32_t num_samples = (uint32_t)(SAMPLE_RATE * duration_sec);
    uint32_t data_size   = num_samples * sizeof(int16_t);
    size_t   total_bytes = sizeof(WavHeader44) + data_size;

    uint8_t *buffer = (uint8_t *)malloc(total_bytes);
    if (!buffer) return NULL;

    WavHeader44 hdr = {
        .riff_id = {'R','I','F','F'}, .file_size = 36 + data_size,
        .wave_id = {'W','A','V','E'}, .fmt_id = {'f','m','t',' '},
        .fmt_size = 16, .audio_format = 1, .num_channels = 1,
        .sample_rate = SAMPLE_RATE, .byte_rate = SAMPLE_RATE * 2,
        .block_align = 2, .bits_per_sample = 16,
        .data_id = {'d','a','t','a'}, .data_size = data_size
    };
    memcpy(buffer, &hdr, sizeof(WavHeader44));

    int16_t *pcm = (int16_t *)(buffer + sizeof(WavHeader44));
    float phase = 0.0f;

    for (uint32_t i = 0; i < num_samples; ++i) {
        float t = (float)i / (float)num_samples; // 정규화 진행률 (0.0 ~ 1.0)
        float freq = start_hz + (end_hz - start_hz) * t;
        float env  = expf(-5.0f * t);            // 지수 감쇠 볼륨 엔벨로프

        phase += (TWO_PI * freq) / (float)SAMPLE_RATE;
        if (phase >= TWO_PI) phase -= TWO_PI;

        float sample_f = sinf(phase) * env;
        pcm[i] = (int16_t)(sample_f * 28000.0f); // 16비트 클리핑 방지 여유폭 확보
    }

    if (out_bytes) *out_bytes = total_bytes;
    return buffer; // raylib LoadWaveFromMemory(".wav", buffer, total_bytes)에 즉시 전달 가능
}

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define SAMPLE_RATE 44100
#define TWO_PI      6.28318530718f

#pragma pack(push, 1)
typedef struct {
    char     riff_id[4];      // "RIFF"
    uint32_t file_size;       // 36 + data_size
    char     wave_id[4];      // "WAVE"
    char     fmt_id[4];       // "fmt "
    uint32_t fmt_size;        // 16 (PCM)
    uint16_t audio_format;    // 1 (Linear Quantization)
    uint16_t num_channels;    // 1 (Mono)
    uint32_t sample_rate;     // 44100
    uint32_t byte_rate;       // sample_rate * num_channels * 2
    uint16_t block_align;     // num_channels * 2
    uint16_t bits_per_sample; // 16
    char     data_id[4];      // "data"
    uint32_t data_size;       // num_samples * 2
} WavHeader44;
#pragma pack(pop)

// Generate a 44-byte WAV header + 16-bit PCM laser/jump sound effect in memory
uint8_t* BuildProceduralSfxWav(float duration_sec, float start_hz, float end_hz, size_t *out_bytes) {
    uint32_t num_samples = (uint32_t)(SAMPLE_RATE * duration_sec);
    uint32_t data_size   = num_samples * sizeof(int16_t);
    size_t   total_bytes = sizeof(WavHeader44) + data_size;

    uint8_t *buffer = (uint8_t *)malloc(total_bytes);
    if (!buffer) return NULL;

    WavHeader44 hdr = {
        .riff_id = {'R','I','F','F'}, .file_size = 36 + data_size,
        .wave_id = {'W','A','V','E'}, .fmt_id = {'f','m','t',' '},
        .fmt_size = 16, .audio_format = 1, .num_channels = 1,
        .sample_rate = SAMPLE_RATE, .byte_rate = SAMPLE_RATE * 2,
        .block_align = 2, .bits_per_sample = 16,
        .data_id = {'d','a','t','a'}, .data_size = data_size
    };
    memcpy(buffer, &hdr, sizeof(WavHeader44));

    int16_t *pcm = (int16_t *)(buffer + sizeof(WavHeader44));
    float phase = 0.0f;

    for (uint32_t i = 0; i < num_samples; ++i) {
        float t = (float)i / (float)num_samples; // Normalized progress (0.0 ~ 1.0)
        float freq = start_hz + (end_hz - start_hz) * t;
        float env  = expf(-5.0f * t);            // Exponential decay volume envelope

        phase += (TWO_PI * freq) / (float)SAMPLE_RATE;
        if (phase >= TWO_PI) phase -= TWO_PI;

        float sample_f = sinf(phase) * env;
        pcm[i] = (int16_t)(sample_f * 28000.0f); // Headroom to prevent 16-bit clipping
    }

    if (out_bytes) *out_bytes = total_bytes;
    return buffer; // Can be passed directly to raylib LoadWaveFromMemory(".wav", buffer, total_bytes)
}