mp3编程要点

(1)mixer设置音量配置

SOUND_MIXER_VOLUME 主音量调节

SOUND_MIXER_RECLEV 录音音量

示例：

#include <linux/soundcard.h>

int fd,iLevel,iRight,iRight;

fd= open("/dev/mixer", O_WRONLY);

iLevel = (iRight << 8) + iLeft;

ioctl(fd, MIXER_WRITE(SOUND_MIXER_VOLUME),&iLevel);

(2)madplay设置采样频率：可以解决播放mp3文件语速过快的问题

system("/bin/madplay --sample-rate=65535 /mp3/left.mp3");