typedef struct FORMAT_CHUNK{
char fccID[4]; //
must be "fmt "
unsigned long dwSize; //
size of this struct, subtracting 8, which is the sizeof fccID and dwSize
// 24-8=16 -->0x10, 0x12
unsigned short wFormatTag; //
one of these: 1: linear,6: a law,7:u-law, FORMAT_TAG
unsigned short wChannels; //
channel number
unsigned long dwSamplesPerSec; //
sampling rate, SAMPLE_RATE,AC44=44100
unsigned long dwAvgBytesPerSec; //
bytes number per second, 2*AC44*2=2B110
//CHANNEL_NUN * SAMPLE_RATE * BYTES_EACH_SAMPLE
unsigned short wBlockAlign; //
每样本的数据位数(按字节算), 其值为:通道,BYTES_EACH_SAMPLE
// 数*每样本的数据位值/8，播放软件需要一次处
// 理多个该值大小的字节数据, 以便将其值用于
// 缓冲区的调整每样本占几个字节
// NumChannels * uiBitsPerSample/8 2* 16/8 =4
unsigned short uiBitsPerSample; //
quantization 1
}FORMAT;
3.12个字节
// The fact chunk is required for all new WAVE formats.
// and is not required for the standard WAVE_FORMAT_PCM files
// 也就是说，这个结构体目前不是必须的，一般当wav文件由某些软件转化而成，则包含该Chunk
// 但如果这里写了，则必须是如下的结构，并且在四个结构体中的位置也要放在第三
typedef struct {
char fccID[4]; // must be "fact"
unsigned long id; // must be 0x4
unsigned long dwSize; // 暂时没发现有啥用， length
}FACT;
4. 8个字节
// 数据结构
typedef struct {
char fccID[4]; //
must be "data"
unsigned long dwSize; // dwSize
= fileSize - 44/56, byte_number of PCM data in byte，WAVE_HEADER.size - dwSize
= 44-8 or 56-8
}DATA;
