wave文件解析

背景

工作需要转换WAV和PCM格式的音频。直接用audition软件另存为就可以把WAV的文件头去掉，但强烈的好奇心驱使下还是想弄清楚都有哪些信息，手动转换格式该怎么做。

RIFF格式

资源交换档案标准（Resource Interchange File Format） (RIFF) 是一种把资料储存在被标记的区块（tagged chunks）中的档案格式(meta-format)：

WAVE文件

一个WAV文件通常有三个chunk以及一个可选chunk，其在文件中的排列方式依次是：RIFF chunk，Format chunk，Fact chunk（附加块，可选），Data chunk。


参考代码

/*
 * @Descripttion: read wave file
 * @version: 0.1.0
 * @Author: PandaYoung
 * @Date: 2023-01-06 16:10:58
 */
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>

#define LOG_DEBUG 1
#define ID_LENGTH 4
#define KILO      1000

typedef struct
{
    char     id[ID_LENGTH];
    uint32_t size;
    char     type[ID_LENGTH];
} RIFF_CHUNK;

typedef struct
{
    char     id[ID_LENGTH];
    uint32_t size;
    uint16_t AudioFmt;
    uint16_t NumChannel;
    uint32_t SampleRate;
    uint32_t ByteRate;
    uint16_t BlockAlign;
    uint16_t BitDepth;
} FORMAT_CHUNK;

typedef struct
{
    char     id[ID_LENGTH];
    uint32_t size;
    uint16_t info[0];
} FACT_CHUNK;

typedef struct
{
    char     id[ID_LENGTH];
    uint32_t size;
    uint16_t data[0];
} DATA_CHUNK;

typedef struct
{
    RIFF_CHUNK   riff_chunk;
    FORMAT_CHUNK format_chunk;
    FACT_CHUNK   fact_chunk;
    DATA_CHUNK   data_chunk;
} WAV;

void print_param(int argc, char *argv[])
{
#if LOG_DEBUG
    printf("argument count: %d\n", argc);
    for (int i = 0; i < argc; i++)
    {
        printf("argument value[%d]: %s\n", i, argv[i]);
    }
#endif
}

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("No file!\n");
        return -1;
    }

    print_param(argc, argv);
    if (access(argv[1], R_OK))
    {
        perror("ERROR: ");
        return -2;
    }

    FILE *fp;
    fp = fopen(argv[1], "rb");
    if (fp ==NULL)
    {
        perror("ERROR: ");
        return -3;
    }

    WAV          wav = {0};
    RIFF_CHUNK   *riff_chunk   = &wav.riff_chunk;
    FORMAT_CHUNK *format_chunk = &wav.format_chunk;
    FACT_CHUNK   *fact_chunk   = &wav.fact_chunk;
    DATA_CHUNK   *data_chunk   = &wav.data_chunk;
    fread(&wav, sizeof(RIFF_CHUNK) + sizeof(FORMAT_CHUNK) + ID_LENGTH, 1, fp);
    printf("ID:\t\t%c%c%c%c\n", riff_chunk->id[0], riff_chunk->id[1], riff_chunk->id[2], riff_chunk->id[3]);
    printf("size:\t\t%d Bytes\n", riff_chunk->size);
    printf("type:\t\t%c%c%c%c\n\n", riff_chunk->type[0], riff_chunk->type[1], riff_chunk->type[2], riff_chunk->type[3]);
    printf("ID:\t\t%c%c%c%c\n", format_chunk->id[0], format_chunk->id[1], format_chunk->id[2], format_chunk->id[3]);
    printf("size:\t\t%d Bytes\n", format_chunk->size);
    printf("AudioFormat:\t%d\n", format_chunk->AudioFmt);
    printf("NumberChannel:\t%d\n", format_chunk->NumChannel);
    printf("SampleRate:\t%.1f kHz\n", (float)format_chunk->SampleRate/KILO);
    printf("ByteRate:\t%d\n", format_chunk->ByteRate);
    printf("BlockAlign:\t%d\n", format_chunk->BlockAlign);
    printf("BitDepth:\t%d\n\n", format_chunk->BitDepth);

    if (strcmp(wav.fact_chunk.id, "data"))
    {
        fread(&wav.fact_chunk.size, sizeof(uint32_t), 1, fp);
        fseek(fp, wav.fact_chunk.size, SEEK_CUR);
        printf("ID:\t\t%c%c%c%c\n", fact_chunk->id[0], fact_chunk->id[1], fact_chunk->id[2], fact_chunk->id[3]);
        printf("size:\t\t%d Bytes\n\n", fact_chunk->size);
    }

    fread(&wav.data_chunk, sizeof(DATA_CHUNK), 1, fp);
    printf("ID:\t\t%c%c%c%c\n", data_chunk->id[0], data_chunk->id[1], data_chunk->id[2], data_chunk->id[3]);
    printf("size:\t\t%d Bytes\n", data_chunk->size);

    fclose(fp);

    return 0;
}