LINUX amixer工具及kcontrol使用

网上对amixer工具的使用较多，但使用kcontrol coding的例子有限，目前比较好的一篇文章如下：

http://blog.chinaunix.net/uid-27875-id-5783294.html

amixer指令：

显示：amixer -c 0 controls

读：amixer -c 0 cget iface=MIXER,name='ADC2L Source PIN Select'

写：amixer -c 0 cset iface=MIXER,name='ADC2L Source PIN Select' 1

以下是基于此参考demo完成的自定义kcontrol的demo code：

const char *str_L = "iface=MIXER,name='ADC2L Source PIN Select'";
char L_PIN = '0';

snd_ctl_t *handle = NULL;
snd_ctl_elem_id_t *id;
snd_ctl_elem_info_t *info;
snd_ctl_elem_value_t *control;


snd_ctl_open(&handle, "hw:0", 0)
snd_ctl_elem_id_alloca(&id);
snd_ctl_elem_info_alloca(&info);
snd_ctl_elem_value_alloca(&control);

snd_ctl_ascii_elem_id_parse(id, str_L);
snd_ctl_elem_info_set_id(info, id);
snd_ctl_elem_info(handle, info)
snd_ctl_elem_info_get_id(info, id);
snd_ctl_elem_value_set_id(control, id);
snd_ctl_elem_read(handle, control)
snd_ctl_ascii_value_parse(handle, control, info, &L_PIN);
snd_ctl_elem_write(handle, control)

snd_ctl_close(handle);