alsa

alsa-utils

　　alsa-utils是alsa驱动测试的一个命令合集，包含alsactl, aconnect, alsamixer, amidi, amixer, aplay, aplaymidi, arecord, arecordmidi,aseqnet, iecset, speaker-test。常用语的命令有alsamixer,amixer,aplay,arecord。其他的用到再看。

1 amixer

amixer -h 查看使用命令

root@linaro-ubuntu-desktop:~# amixer -hUsage: amixer <options> [command]Available options:  -h,--help       this help  -c,--card N     select the card //指定声卡，默认为声卡0  -D,--device N   select the device, default 'default'  -d,--debug      debug mode  -n,--nocheck    do not perform range checking  -v,--version    print version of this program  -q,--quiet      be quiet  -i,--inactive   show also inactive controls  -a,--abstract L select abstraction level (none or basic)  -s,--stdin      Read and execute commands from stdin sequentiallyAvailable commands:  scontrols       show all mixer simple controls  scontents   show contents of all mixer simple controls (default command)  sset sID P      set contents for one mixer simple control //sset sget用于操作  sget sID        get contents for one mixer simple control //simple control  controls        show all controls for given card  contents        show contents of all controls for given card  cset cID P      set control contents for one control //cset cget用于操作controls  cget cID        get control contents for one control

　　amixer contorls/scontrols 查看当前声卡有哪些control，两个命令显示格式不一样

root@linaro-ubuntu-desktop:~# amixer controlsnumid=25,iface=MIXER,name='Headphone Aux Volume'numid=26,iface=MIXER,name='Headphone Mixer Switch'numid=24,iface=MIXER,name='Headphone ZC Switch'numid=23,iface=MIXER,name='Headphone Switch'numid=22,iface=MIXER,name='Headphone Volume'numid=20,iface=MIXER,name='ADC High Performance Switch'numid=14,iface=MIXER,name='Capture HPF Cutoff'numid=13,iface=MIXER,name='Capture HPF Mode'numid=12,iface=MIXER,name='Capture HPF Switch'numid=16,iface=MIXER,name='Capture LHPF Mode'numid=15,iface=MIXER,name='Capture LHPF Switch'numid=11,iface=MIXER,name='Capture ZC Switch'numid=10,iface=MIXER,name='Capture Switch'numid=9,iface=MIXER,name='Capture Volume'

root@linaro-ubuntu-desktop:~# amixer scontrolsSimple mixer control 'Headphone',0Simple mixer control 'Headphone Aux',0Simple mixer control 'Headphone Mixer',0Simple mixer control 'Headphone ZC',0Simple mixer control 'Speaker',0Simple mixer control 'Speaker Boost',0Simple mixer control 'Speaker Mixer',0Simple mixer control 'Speaker ZC',0Simple mixer control 'Sidetone',0Simple mixer control 'Beep',0Simple mixer control 'Capture',0Simple mixer control 'Capture HPF',0Simple mixer control 'Capture HPF Cutoff',0

　　amixer contents/scontents 查看当前声卡control的内容及选项，两个命令显示格式不一样

root@linaro-ubuntu-desktop:~# amixer contentsnumid=25,iface=MIXER,name='Headphone Aux Volume'  ; type=INTEGER,access=rw---R--,values=2,min=0,max=7,step=0  : values=7,7  | dBscale-min=-7.00dB,step=1.00dB,mute=0numid=26,iface=MIXER,name='Headphone Mixer Switch'  ; type=BOOLEAN,access=rw------,values=2  : values=off,offnumid=24,iface=MIXER,name='Headphone ZC Switch'  ; type=BOOLEAN,access=rw------,values=2  : values=off,offnumid=23,iface=MIXER,name='Headphone Switch'  ; type=BOOLEAN,access=rw------,values=2  : values=on,onnumid=22,iface=MIXER,name='Headphone Volume'  ; type=INTEGER,access=rw---R--,values=2,min=0,max=127,step=0  : values=121,121  | dBscale-min=-121.00dB,step=1.00dB,mute=1

root@linaro-ubuntu-desktop:~# amixer scontentsSimple mixer control 'Headphone',0  Capabilities: volume pswitch penum  Playback channels: Front Left - Front Right  Capture channels: Front Left - Front Right  Limits: 0 - 127  Front Left: 121 [95%] [0.00dB] Playback [on]  Front Right: 121 [95%] [0.00dB] Playback [on]Simple mixer control 'Headphone Aux',0  Capabilities: volume penum  Playback channels: Front Left - Front Right  Capture channels: Front Left - Front Right  Limits: 0 - 7  Front Left: 7 [100%] [0.00dB]  Front Right: 7 [100%] [0.00dB]Simple mixer control 'Headphone Mixer',0  Capabilities: pswitch penum  Playback channels: Front Left - Front Right  Mono:  Front Left: Playback [off]  Front Right: Playback [off]Simple mixer control 'Headphone ZC',0  Capabilities: pswitch penum  Playback channels: Front Left - Front Right  Mono:  Front Left: Playback [off]  Front Right: Playback [off]

　　amixer cset/cget 设置amixer controls中显示的controls中具体的某个controls详细信息，包含最大值，最小值，当前值，可设置的值范围。可以不输入完整control，只要能标识control，如下代码

root@linaro-ubuntu-desktop:~# amixer cget numid=9numid=9,iface=MIXER,name='Capture Volume'  ; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0  : values=63,63  | dBscale-min=-23.25dB,step=0.75dB,mute=0root@linaro-ubuntu-desktop:~# amixer cget numid=9,iface=MIXER,name='Capture Volume'   ; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0  : values=63,63  | dBscale-min=-23.25dB,step=0.75dB,mute=0

　　amixer cset改变control的值

root@linaro-ubuntu-desktop:~# amixer cset numid=9 31numid=9,iface=MIXER,name='Capture Volume'  ; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0  : values=31,31  | dBscale-min=-23.25dB,step=0.75dB,mute=0

2 alsamixer

　　命令格式: alsamixer [options]
　　命令选项:

   -h, -help 显示帮助信息   -c <card number or idenfication> 指定需要设置的声卡.默认为0   -D <device identification>   选择需要控制的调节器   -g 设置界面颜色   -s 最小化界面窗口

　　进入alsamixerl图形界面后,可以使用下面命令操作:

    左右箭头或n,p    用来选择通道    上下箭头或+,-    同时调整选定通道的左右声道的音量    B,= 设置左右声道音量相同    M静音当前通道    < > 分别对左,右声道静音    空格  选择录音源.在选定的通道上按"空格",可以标记此通道为录音源.此操作仅限输入设备.插入键或";",删除键或"'"分别选定左右通道    L 刷新屏幕.    PageUp  增大5格音量    PageDown    减小5格音量    End 设置音量为0    分别调整左,右或整个通道的音量    Q,W,E   增大 左,右,通道 的音量    Z,X,C   减小 左,右,通道 的音量    alt-q,ESC   退出

3 aplay

　　aplay -h 可以查看相关用法，对于aplay简单使用
　　查看当前声卡

root@linaro-ubuntu-desktop:# aplay -l**** List of PLAYBACK Hardware Devices ****card 0: wm8962audio [wm8962-audio], device 0: HiFi wm8962-0 []  Subdevices: 1/1  Subdevice #0: subdevice #0card 1: imxhdmisoc [imx-hdmi-soc], device 0: IMX HDMI TX mxc-hdmi-soc-0 []  Subdevices: 1/1  Subdevice #0: subdevice #0

　　播放wav格式音频

aplay test.wav

alsa配置文件

　　alsa配置文件主要在/usr/share/alsa目录下， 最重要的是alsa.conf文件。ubuntu下使用dpkg -S alsa.conf，可以看到alsa.conf是libasound2-data包的一个文件。

rpdzkj@ubuntu:~$ dpkg -S alsa.conflibasound2-data: /usr/share/alsa/alsa.conf.d/READMElibasound2-data: /usr/share/alsa/alsa.conflibasound2-plugins:amd64: /usr/share/alsa/alsa.conf.d/99-pulseaudio-default.conf.example

　　alsa.conf文件中使用hook读取了/etc/asound.conf和~/.asoundrc两个配置文件，用户相关的个性化配置可写到这两个文件。

rpdzkj@ubuntu:~$ cat /usr/share/alsa/alsa.conf@hooks [    {        func load        files [            {                @func concat                strings [                    { @func datadir }                    "/alsa.conf.d/"                ]            }            "/etc/asound.conf"            "~/.asoundrc"        ]        errors false    }]

　　利用.asoundrc和asound.conf可指定ubuntu下默认声卡，将下面代码添加到其中一个配置文件中

defaults.pcm.card 1     //aplay -l 显示系统中所有声卡,可能需要root权限执行, 1为对应声卡的编号defaults.ctl.card 1