标签：技术分享 开发 存储 一个 out memcpy image change fclose
转自：http://www.cnblogs.com/CoderTian/p/6657844.html
WAV为微软公司（Microsoft)开发的一种声音文件格式，它符合RIFF(Resource Interchange File Format)文件规范，用于保存Windows平台的音频信息资源，被Windows平台及其应用程序所广泛支持。WAVE文件通常只是一个具有单个“WAVE”块的RIFF文件，该块由两个子块（”fmt”子数据块和”data”子数据块），它的格式如下图所示
该格式的实质就是在PCM文件的前面加了一个文件头，每个字段的的含义为
typedef struct{
char ChunkID[4];//内容为"RIFF"
unsigned long ChunkSize;//存储文件的字节数（不包含ChunkID和ChunkSize这8个字节）
char Format[4];//内容为"WAVE"
}WAVE_HEADER;
typedef struct{
char Subchunk1ID[4];//内容为"fmt"
unsigned long Subchunk1Size;//存储该子块的字节数（不含前面的Subchunk1ID和Subchunk1Size这8个字节）
unsigned short AudioFormat;//存储音频文件的编码格式，例如若为PCM则其存储值为1，若为其他非PCM格式的则有一定的压缩。
unsigned short NumChannels;//通道数，单通道(Mono)值为1，双通道(Stereo)值为2，等等
unsigned long SampleRate;//采样率，如8k，44.1k等
unsigned long ByteRate;//每秒存储的bit数，其值=SampleRate * NumChannels * BitsPerSample/8
unsigned short BlockAlign;//块对齐大小，其值=NumChannels * BitsPerSample/8
unsigned short BitsPerSample;//每个采样点的bit数，一般为8,16,32等。
}WAVE_FMT;
typedef struct{
char Subchunk2ID[4];//内容为“data”
unsigned long Subchunk2Size;//内容为接下来的正式的数据部分的字节数，其值=NumSamples * NumChannels * BitsPerSample/8
}WAVE_DATA;
比如下面的例子
这里是一个WAVE文件的开头72字节，字节显示为十六进制数字：
52 49 46 46 24 08 00 00 57 41 56 45 66 6d 74 20 10 00 00 00 01 00 02 00
22 56 00 00 88 58 01 00 04 00 10 00 64 61 74 61 00 08 00 00 00 00 00 00
24 17 1e f3 3c 13 3c 14 16 f9 18 f9 34 e7 23 a6 3c f2 24 f2 11 ce 1a 0d
字段解析：
pcm 加上WAV header的代码实现为
int simplest_pcm16le_to_wave(const char *pcmpath,int channels,int sample_rate,const char *wavepath)
{
typedef struct WAVE_HEADER{
char fccID[4];
unsigned long dwSize;
char fccType[4];
}WAVE_HEADER;
typedef struct WAVE_FMT{
char fccID[4];
unsigned long dwSize;
unsigned short wFormatTag;
unsigned short wChannels;
unsigned long dwSamplesPerSec;
unsigned long dwAvgBytesPerSec;
unsigned short wBlockAlign;
unsigned short uiBitsPerSample;
}WAVE_FMT;
typedef struct WAVE_DATA{
char fccID[4];
unsigned long dwSize;
}WAVE_DATA;
if(channels==0||sample_rate==0){
channels = 2;
sample_rate = 44100;
}
int bits = 16;
WAVE_HEADER pcmHEADER;
WAVE_FMT pcmFMT;
WAVE_DATA pcmDATA;
unsigned short m_pcmData;
FILE *fp,*fpout;
fp=fopen(pcmpath, "rb");
if(fp == NULL) {
printf("open pcm file error\n");
return -1;
}
fpout=fopen(wavepath, "wb+");
if(fpout == NULL) {
printf("create wav file error\n");
return -1;
}
//WAVE_HEADER
memcpy(pcmHEADER.fccID,"RIFF",strlen("RIFF"));
memcpy(pcmHEADER.fccType,"WAVE",strlen("WAVE"));
fseek(fpout,sizeof(WAVE_HEADER),1);
//WAVE_FMT
pcmFMT.dwSamplesPerSec=sample_rate;
pcmFMT.dwAvgBytesPerSec=pcmFMT.dwSamplesPerSec*sizeof(m_pcmData);
pcmFMT.uiBitsPerSample=bits;
memcpy(pcmFMT.fccID,"fmt ",strlen("fmt "));
pcmFMT.dwSize=16;
pcmFMT.wBlockAlign=2;
pcmFMT.wChannels=channels;
pcmFMT.wFormatTag=1;
fwrite(&pcmFMT,sizeof(WAVE_FMT),1,fpout);
//WAVE_DATA;
memcpy(pcmDATA.fccID,"data",strlen("data"));
pcmDATA.dwSize=0;
fseek(fpout,sizeof(WAVE_DATA),SEEK_CUR);
fread(&m_pcmData,sizeof(unsigned short),1,fp);
while(!feof(fp)){
pcmDATA.dwSize+=2;
fwrite(&m_pcmData,sizeof(unsigned short),1,fpout);
fread(&m_pcmData,sizeof(unsigned short),1,fp);
}
pcmHEADER.dwSize=44+pcmDATA.dwSize;
rewind(fpout);
fwrite(&pcmHEADER,sizeof(WAVE_HEADER),1,fpout);
fseek(fpout,sizeof(WAVE_FMT),SEEK_CUR);
fwrite(&pcmDATA,sizeof(WAVE_DATA),1,fpout);
fclose(fp);
fclose(fpout);
return 0;
}
标签：技术分享 开发 存储 一个 out memcpy image change fclose
原文地址：http://www.cnblogs.com/fellow1988/p/7113270.html
