wav_header.h

#pragma once
#include <stdint.h>

/**
 * @brief Header structure for WAV file with only one data chunk
 *
 * @note See this for reference: http://soundfile.sapp.org/doc/WaveFormat/
 *
 * @note Assignment to variables in this struct directly is only possible for little endian architectures
 *       (including Xtensa & RISC-V)
 */

typedef struct {
    char chunk_id[4];         /*!< Contains the letters "RIFF" in ASCII form */
    uint32_t chunk_size;      /*!< This is the size of the rest of the chunk following this number */
    char chunk_format[4];     /*!< Contains the letters "WAVE" */
} __attribute__((packed)) wav_descriptor_chunk_t; /*!< Canonical WAVE format starts with the RIFF header */

typedef struct {
    char subchunk_id[4];      /*!< Contains the letters "fmt " */
    uint32_t subchunk_size;   /*!< PCM = 16, This is the size of the rest of the Subchunk which follows this number */
    uint16_t audio_format;    /*!< PCM = 1, values other than 1 indicate some form of compression */
    uint16_t num_of_channels; /*!< Mono = 1, Stereo = 2, etc. */
    uint32_t sample_rate;     /*!< 8000, 44100, etc. */
    uint32_t byte_rate;       /*!< ==SampleRate * NumChannels * BitsPerSample s/ 8 */
    uint16_t block_align;     /*!< ==NumChannels * BitsPerSample / 8 */
    uint16_t bits_per_sample; /*!< 8 bits = 8, 16 bits = 16, etc. */
} __attribute__((packed)) pcm_wav_fmt_chunk_t; /*!< The "fmt " subchunk describes the sound data's format */

typedef struct {
    char subchunk_id[4];      /*!< Contains the letters "fmt " */
    uint32_t subchunk_size;   /*!< ALAW/MULAW = 18, This is the size of the rest of the Subchunk which follows this number */
    uint16_t audio_format;    /*!< ALAW = 6, MULAW = 7, values other than 1 indicate some form of compression */
    uint16_t num_of_channels; /*!< ALAW/MULAW = 1, Mono = 1, Stereo = 2, etc. */
    uint32_t sample_rate;     /*!< ALAW/MULAW = 8000, 8000, 44100, etc. */
    uint32_t byte_rate;       /*!< ALAW/MULAW = 8000, ==SampleRate * NumChannels * BitsPerSample s/ 8 */
    uint16_t block_align;     /*!< ALAW/MULAW = 1, ==NumChannels * BitsPerSample / 8 */
    uint16_t bits_per_sample; /*!< ALAW/MULAW = 8, 8 bits = 8, 16 bits = 16, etc. */
    uint16_t ext_size;        /*!< ALAW/MULAW = 0, Size of the extension (0 or 22) */
} __attribute__((packed)) non_pcm_wav_fmt_chunk_t; /*!< The "fmt " subchunk describes the sound data's format */

typedef struct {
    char subchunk_id[4];      /*!< Contains the letters "data" */
    uint32_t subchunk_size;   /*!< ==NumSamples * NumChannels * BitsPerSample / 8 */
} __attribute__((packed)) wav_data_chunk_t; /*!< The "data" subchunk contains the size of the data and the actual sound */

typedef struct {
    wav_descriptor_chunk_t descriptor_chunk;  /*!< Canonical WAVE format starts with the RIFF header */
    pcm_wav_fmt_chunk_t fmt_chunk;            /*!< The "fmt " subchunk describes the sound data's format */
    wav_data_chunk_t data_chunk;              /*!< The "data" subchunk contains the size of the data and the actual sound */
} __attribute__((packed)) pcm_wav_header_t;

typedef struct {
    wav_descriptor_chunk_t descriptor_chunk;  /*!< Canonical WAVE format starts with the RIFF header */
    non_pcm_wav_fmt_chunk_t fmt_chunk;        /*!< The "fmt " subchunk describes the sound data's format */
    wav_data_chunk_t data_chunk;              /*!< The "data" subchunk contains the size of the data and the actual sound */
} __attribute__((packed)) non_pcm_wav_header_t;

#define WAVE_FORMAT_PCM         1 // PCM
#define WAVE_FORMAT_IEEE_FLOAT  3 // IEEE float
#define WAVE_FORMAT_ALAW        6 // 8-bit ITU-T G.711 A-law
#define WAVE_FORMAT_MULAW       7 // 8-bit ITU-T G.711 µ-law

#define PCM_WAV_HEADER_SIZE     44
#define NON_PCM_WAV_HEADER_SIZE 46

/**
 * @brief Default header for PCM format WAV files
 *
 */
#define PCM_WAV_HEADER_DEFAULT(wav_sample_size, wav_sample_bits, wav_sample_rate, wav_channel_num) { \
    .descriptor_chunk = { \
        .chunk_id = {'R', 'I', 'F', 'F'}, \
        .chunk_size = (wav_sample_size) + sizeof(pcm_wav_header_t) - 8, \
        .chunk_format = {'W', 'A', 'V', 'E'} \
    }, \
    .fmt_chunk = { \
        .subchunk_id = {'f', 'm', 't', ' '}, \
        .subchunk_size = 16, /* 16 for PCM */ \
        .audio_format = WAVE_FORMAT_PCM, /* 1 for PCM */ \
        .num_of_channels = (uint16_t)(wav_channel_num), \
        .sample_rate = (wav_sample_rate), \
        .byte_rate = (wav_sample_bits) * (wav_sample_rate) * (wav_channel_num) / 8, \
        .block_align = (uint16_t)((wav_sample_bits) * (wav_channel_num) / 8), \
        .bits_per_sample = (uint16_t)(wav_sample_bits)\
    }, \
    .data_chunk = { \
        .subchunk_id = {'d', 'a', 't', 'a'}, \
        .subchunk_size = (wav_sample_size) \
    } \
}