C语言实现获得wav文件播放总时间

// 单位：秒
double get_wav_time_length(char* filename)
{
double len = 0.0;

if (filename != NULL)
{
FILE* fp;
fp = fopen(filename, "rb");
if (fp != NULL)
{
int i;
int j;
fseek(fp, 28, SEEK_SET);
fread(&i, sizeof(i), 1, fp);
fseek(fp, 40, SEEK_SET);
fread(&j, sizeof(j), 1, fp);

fclose(fp);
fp = NULL;

len = (double)j/(double)i;
}
}

return len;
}