1、wav音频文件的格式
wav文件由文件头和采样数据2部分组成。
文件头又分为RIFF（Resource Interchange File Format）、WAVE文件标识段 和 声音数据格式说明段组成。
各段的起始地址分别由RIFF标识符、WAVE标识符、以及波形格式标识符（FMT）标定。
（1）文件头格式
注意：下面的地址是连续的
（2）数据格式
虽然上图给出的数据标识符起始地址刚好是文件头的末地址+1，但并不代表总是这样。
因此，我们在读取数据时最好是找到数据标识符，该标识符的4个字节刚好是'd'、‘a’、‘t’、‘a’。
2、C语言读取wav文件
首先对一些类型使用了重定义
typedef unsigned char uchar;
typedef unsigned char uint8;
typedef unsigned short uint16;
typedef unsigned long uint32;
typedef char sint8;
typedef short sint16;
typedef long sint32;
typedef float fp32;
typedef double fp64;
typedef enum BOOLEAN
{
TRUE = 1,
FALSE = 0
} boolean;
（1）wav结构体定义
//wave文件头typedef struct WaveHeader{uint8 riff[4]; //资源交换文件标志uint32 size; //从下个地址开始到文件结尾的字节数uint8 wave_flag[4]; //wave文件标识uint8 fmt[4]; //波形格式标识uint32 fmt_len; //过滤字节(一般为00000010H)uint16 tag; //格式种类，值为1时，表示PCM线性编码uint16 channels; //通道数，单声道为1，双声道为2uint32 samp_freq; //采样频率uint32 byte_rate; //数据传输率 (每秒字节＝采样频率×每个样本字节数)uint16 block_align; //块对齐字节数 = channles * bit_samp / 8uint16 bit_samp; //bits per sample (又称量化位数)} wave_header_t;typedef struct WaveStruct{FILE *fp; //file pointerwave_header_t header; //headeruint8 data_flag[4]; //数据标识符uint32 length; //采样数据总数uint32 *pData; //data} wave_t;wave_t wave;
（2）读取文件头信息
/* * open *.wav file */void WaveOpen(char *file, int raw, int mono_stereo){uchar temp = 0;uint8 read_bytes = 0;char *channel_mappings[] = {NULL,"mono","stereo"};uint32 total_time = 0;struct PlayTime //播放时间{uint8 hour;uint8 minute;uint8 second;} play_time;if(NULL == (wave.fp=fopen(file, "rb"))) /* open file */{printf("file %s open failure!\n", file);}/* read heade information */if(4 != fread(wave.header.riff, sizeof(uint8), 4, wave.fp)) /* RIFF chunk */{printf("read riff error!\n");return;}if(1 != fread(&wave.header.size, sizeof(uint32), 1, wave.fp)) /* SIZE : from here to file end */{printf("read size error!\n");return;}if(4 != fread(wave.header.wave_flag, sizeof(uint8), 4, wave.fp)) /* wave file flag */{printf("read wave_flag error!\n");return;}if(4 != fread(wave.header.fmt, sizeof(uint8), 4, wave.fp)) /* fmt chunk */{printf("read fmt error!\n");return;}if(1 != fread(&wave.header.fmt_len, sizeof(uint32), 1, wave.fp)) /* fmt length */{printf("read fmt_len error!\n");return;}if(1 != fread(&wave.header.tag, sizeof(uint16), 1, wave.fp)) /* tag : PCM or not */{printf("read tag error!\n");return;}if(1 != fread(&wave.header.channels, sizeof(uint16), 1, wave.fp)) /* channels */{printf("read channels error!\n");return;}if(1 != fread(&wave.header.samp_freq, sizeof(uint32), 1, wave.fp)) /* samp_freq */{printf("read samp_freq error!\n");return;}if(1 != fread(&wave.header.byte_rate, sizeof(uint32), 1, wave.fp)) /* byte_rate : decode how many bytes per second */{ /* byte_rate = samp_freq * bit_samp */printf("read byte_rate error!\n");return;}if(1 != fread(&wave.header.block_align, sizeof(uint16), 1, wave.fp)) /* quantize bytes for per samp point */{printf("read byte_samp error!\n");return;}if(1 != fread(&wave.header.bit_samp, sizeof(uint16), 1, wave.fp)) /* quantize bits for per samp point */{ /* bit_samp = byte_samp * 8 */printf("read bit_samp error!\n");return;}/* jump to "data" for reading data */do{fread(&temp, sizeof(uchar), 1, wave.fp);}while('d' != temp);wave.data_flag[0] = temp;if(3 != fread(&wave.data_flag[1], sizeof(uint8), 3, wave.fp)) /* data chunk */{printf("read header data error!\n");return;}if(1 != fread(&wave.length, sizeof(uint32), 1, wave.fp)) /* data length */{printf("read length error!\n");}/* jduge data chunk flag */if(!StrCmp(wave.data_flag, "data", 4)){printf("error : cannot read data!\n");return;}total_time = wave.length / wave.header.byte_rate;play_time.hour = (uint8)(total_time / 3600);play_time.minute = (uint8)((total_time / 60) % 60);play_time.second = (uint8)(total_time % 60);/* printf file header information */printf("%s %ldHz %dbit, DataLen: %ld, Rate: %ld, Length: %2ld:%2ld:%2ld\n", channel_mappings[wave.header.channels], //声道 wave.header.samp_freq, //采样频率 wave.header.bit_samp, //每个采样点的量化位数 wave.length, wave.header.byte_rate, play_time.hour,play_time.minute,play_time.second);//fclose(wave.fp); /* close wave file */}
按结构体一点点的读出文件头的信息，请注意
/* jump to "data" for reading data */
的那一段，“先识别data标识符，再接着往下读取”。
（3）读数据
在读完数据长度之后就全是数据了，直接使用fread按uint32格式读取数据即可，我这里每次读取1152个数据（即一帧）。
/* * get wave data */uint32* GetWave(void){static uint32 buffer[1152] = {0};uint16 n = 1152;uint16 p = 0;p = fread(buffer, sizeof(uint32), n, wave.fp);if(!p){return 0;}else{for(; p<n; p++){buffer[p] = 0;}return buffer;}}
上面程序中注意几点，
（1）不要定义大容量的局部变量，因为局部变量存放在堆栈中。如果一定要定义，要定义成static类型。
（2）不要返回局部变量的的地址，因为在堆栈中的地址值是不确定的。
（3）对于for(; p<n; p++）指当读出的数据不满一帧的时候，在后面补0到一帧，一般这样方便后期处理
上面的程序返回局部数组的指针，前提是 已经将数据存放在静态数据存储区。
但不管怎样，返回局部变量的地址总是不好的。