把音频数据保存 wav文件， save audio data to wav file

最新推荐文章于 2024-08-22 11:40:32 发布

原创最新推荐文章于 2024-08-22 11:40:32 发布 · 1.4k 阅读

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CC 4.0 BY-SA版权

文章标签：

#audio #byte #header #character #struct #buffer

本文详细介绍了WAV音频文件的内部结构，包括关键字段如'wFormatTag'的定义及用途，以及如何使用C语言创建并初始化WAV文件头。通过具体的代码示例，读者可以了解如何设置采样率、声道数等参数。

部署运行你感兴趣的模型镜像

/* this play_buffer holds the digitized audio */
//unsigned char buf[LENGTH*RATE*SIZE*CHANNELS/8];
typedef unsigned char   BYTE;
typedef unsigned short WORD;
typedef unsigned int DWORD;
typedef unsigned int FOURCC;   /* a four character code */

/* flags for 'wFormatTag' field of WAVEFORMAT */
#define WAVE_FORMAT_PCM 1

/* MMIO macros */
#define mmioFOURCC(ch0, ch1, ch2, ch3) /
((DWORD)(BYTE)(ch0) | ((DWORD)(BYTE)(ch1) << 8) | /
((DWORD)(BYTE)(ch2) << 16) | ((DWORD)(BYTE)(ch3) << 24))

#define FOURCC_RIFF   mmioFOURCC ('R', 'I', 'F', 'F')
#define FOURCC_LIST   mmioFOURCC ('L', 'I', 'S', 'T')
#define FOURCC_WAVE   mmioFOURCC ('W', 'A', 'V', 'E')
#define FOURCC_FMT   mmioFOURCC ('f', 'm', 't', ' ')
#define FOURCC_DATA   mmioFOURCC ('d', 'a', 't', 'a')

typedef struct CHUNKHDR {
    FOURCC ckid;       /* chunk ID */
    DWORD dwSize;             /* chunk size */
} CHUNKHDR;

/* simplified Header for standard WAV files */
typedef struct WAVEHDR {
    CHUNKHDR chkRiff;
    FOURCC fccWave;
    CHUNKHDR chkFmt;
    WORD wFormatTag;       /* format type */
    WORD nChannels;       /* number of channels (i.e. mono, stereo, etc.) */
    DWORD nSamplesPerSec; /* sample rate */
    DWORD nAvgBytesPerSec; /* for play_buffer estimation */
    WORD nBlockAlign;       /* block size of data */
    WORD wBitsPerSample;
    CHUNKHDR chkData;
} WAVEHDR;

#if BYTE_ORDER == BIG_ENDIAN
# define cpu_to_le32(x) SWAP4((x))
# define cpu_to_le16(x) SWAP2((x))
# define le32_to_cpu(x) SWAP4((x))
# define le16_to_cpu(x) SWAP2((x))
#else
# define cpu_to_le32(x) (x)
# define cpu_to_le16(x) (x)
# define le32_to_cpu(x) (x)
# define le16_to_cpu(x) (x)
#endif

static void wav_init_header(WAVEHDR *fileheader)
{
    /* stolen from cdda2wav */
    int nBitsPerSample = 16;
    int channels       = 1;
    int rate           = 8000;

    unsigned long nBlockAlign = channels * ((nBitsPerSample + 7) / 8);
    unsigned long nAvgBytesPerSec = nBlockAlign * rate;
    unsigned long temp = /* data length */ 0 +
   sizeof(WAVEHDR) - sizeof(CHUNKHDR);

    fileheader->chkRiff.ckid    = cpu_to_le32(FOURCC_RIFF);
    fileheader->fccWave         = cpu_to_le32(FOURCC_WAVE);
    fileheader->chkFmt.ckid     = cpu_to_le32(FOURCC_FMT);
    fileheader->chkFmt.dwSize   = cpu_to_le32(16);
    fileheader->wFormatTag      = cpu_to_le16(WAVE_FORMAT_PCM);
    fileheader->nChannels       = cpu_to_le16(channels);
    fileheader->nSamplesPerSec = cpu_to_le32(rate);
    fileheader->nAvgBytesPerSec = cpu_to_le32(nAvgBytesPerSec);
    fileheader->nBlockAlign     = cpu_to_le16(nBlockAlign);
    fileheader->wBitsPerSample = cpu_to_le16(nBitsPerSample);
    fileheader->chkData.ckid    = cpu_to_le32(FOURCC_DATA);
    fileheader->chkRiff.dwSize = cpu_to_le32(temp);
    fileheader->chkData.dwSize = cpu_to_le32(0 /* data length */);
}

static void wav_start_write(FILE* fd, WAVEHDR *fileheader)
{
    wav_init_header(fileheader);
    fwrite(fileheader,1, sizeof(WAVEHDR), fd);
}

static void wav_stop_write(FILE* fd, WAVEHDR *fileheader, int wav_size)
{
    unsigned long temp = wav_size + sizeof(WAVEHDR) - sizeof(CHUNKHDR);

    fileheader->chkRiff.dwSize = cpu_to_le32(temp);
    fileheader->chkData.dwSize = cpu_to_le32(wav_size);
    fseek(fd,0,SEEK_SET);
    fwrite(fileheader,1, sizeof(WAVEHDR), fd);
}