头几天在嵌入式linux上用到alsa command，网上查的资料多不给力，只有动手1点点查，终究可以用了，将这个使用方法告知大家，以避免大家少走弯路。
0.先查看系统支持哪几个alsa cmd:
ll /system/bin/asla*
经查，我的android4.4.2+linux3.10 的系统支持以下 alsa cmd
-rwxr-xr-x root shell 68242 2014⑴0-08 05:18 alsa_amixer
-rwxr-xr-x root shell 67639 2014⑴0-08 05:18 alsa_aplay
-rwxr-xr-x root shell 130323 2014⑴0-08 05:18 alsa_ctl
不同的系统可以稍有不同，比如有的系统就叫aplayamixer .....
1.如何使用alsa_aplay:
alsa_aplay -h //看1下目前支持哪些用法
-h, --help help
--version print current version
-l, --list-devices list all soundcards and digital audio devices
-L, --list-pcms list device names
-D, --device=NAME select PCM by name
-q, --quiet quiet mode
-t, --file-type TYPE file type (voc, wav, raw or au)
-c, --channels=# channels
-f, --format=FORMAT sample format (case insensitive)
-r, --rate=# sample rate
-d, --duration=# interrupt after # seconds
-M, --mmap mmap stream
-N, --nonblock nonblocking mode
-F, --period-time=# distance between interrupts is # microseconds
-B, --buffer-time=# buffer duration is # microseconds
--period-size=# distance between interrupts is # frames
--buffer-size=# buffer duration is # frames
-A, --avail-min=# min available space for wakeup is # microseconds
-R, --start-delay=# delay for automatic PCM start is # microseconds
(relative to buffer size if <= 0)
-T, --stop-delay=# delay for automatic PCM stop is # microseconds from xrun
-v, --verbose show PCM structure and setup (accumulative)
-V, --vumeter=TYPE enable VU meter (TYPE: mono or stereo)
-I, --separate-channels one file for each channel
--disable-resample disable automatic rate resample
--disable-channels disable automatic channel conversions
--disable-format disable automatic format conversions
--disable-softvol disable software volume control (softvol)
--test-position test ring buffer position
--test-coef=# test coeficient for ring buffer position (default 8)
expression for validation is: coef * (buffer_size / 2)
--test-nowait do not wait for ring buffer - eats whole CPU
--max-file-time=# start another output file when the old file has recorded
for this many seconds
--process-id-file write the process ID here
--use-strftime apply the strftime facility to the output file name
会有详细的help说明，这个就不说了，可以自己试。
alsa_aplay -l //列出系统有几个声卡（card 0/1/2....）, 及每一个卡的1个装备（device 0/1/2....）
比如我的系统为：
**** List of PLAYBACK Hardware Devices ****
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 0: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 1: IntelALSASSP [IntelALSASSP], device 0: BT_DEVICE [IntelALSASSP]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: IntelALSASSP [IntelALSASSP], device 2: BUILTIN_DEVICE [IntelALSASSP]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 0: 4 []
Subdevices: 2/2
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
card 2: cloverviewaudio [cloverview_audio], device 1: Voice rt5640-aif2⑴ []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 3: BTSCO snd-soc-dummy-dai⑶ []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 4: VOIP rt5640-aif2⑷ []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 5: IFX_MODEM_MIXING snd-soc-dummy-dai⑸ []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 6: virtual-stream rt5640-aif1⑹ []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: cloverviewaudio [cloverview_audio], device 7: CTP Probe snd-soc-dummy-dai⑺ []
Subdevices: 1/1
Subdevice #0: subdevice #0
由于我的codec 为alc5640,所以
从上面得知alc5640挂在card2上，所以以后我们当配置amixer 5640时就-c 2 就对了。
2. alsa_amixer的用法
alsa_amixer -h //1样的help,这里不列了。
用alc5640进行mixer控制的用法：
# alsa_amixer -c 2 controls
以下：
alsa_amixer -c 2 controls
numid=35,iface=MIXER,name='Headphone Switch'
numid=20,iface=MIXER,name='Mono ADC Capture Volume'
numid=122,iface=MIXER,name='Mono ADC L1 Mux'
numid=123,iface=MIXER,name='Mono ADC L2 Mux'
numid=114,iface=MIXER,name='Mono ADC MIXL ADC1 Switch'
numid=115,iface=MIXER,name='Mono ADC MIXL ADC2 Switch'
numid=112,iface=MIXER,name='Mono ADC MIXR ADC1 Switch'
numid=113,iface=MIXER,name='Mono ADC MIXR ADC2 Switch'
numid=121,iface=MIXER,name='Mono ADC R1 Mux'
numid=120,iface=MIXER,name='Mono ADC R2 Mux'
numid=93,iface=MIXER,name='Mono DAC MIXL DAC L1 Switch'
numid=94,iface=MIXER,name='Mono DAC MIXL DAC L2 Switch'
numid=95,iface=MIXER,name='Mono DAC MIXL DAC R2 Switch'
numid=92,iface=MIXER,name='Mono DAC MIXR DAC L2 Switch'
numid=90,iface=MIXER,name='Mono DAC MIXR DAC R1 Switch'
numid=91,iface=MIXER,name='Mono DAC MIXR DAC R2 Switch'
numid=11,iface=MIXER,name='Mono DAC Playback Volume'
numid=44,iface=MIXER,name='Mono MIX BST1 Switch'
numid=41,iface=MIXER,name='Mono MIX DAC L2 Switch'
numid=40,iface=MIXER,name='Mono MIX DAC R2 Switch'
numid=43,iface=MIXER,name='Mono MIX OUTVOL L Switch'
numid=42,iface=MIXER,name='Mono MIX OUTVOL R Switch'
numid=85,iface=MIXER,name='Mono dacr Mux'
numid=8,iface=MIXER,name='Mono Playback Switch'
numid=21,iface=MIXER,name='ADC Boost Gain'
numid=24,iface=MIXER,name='ADC IF1 Data Switch'
numid=26,iface=MIXER,name='ADC IF2 Data Switch'
numid=18,iface=MIXER,name='ADC Capture Switch'
numid=19,iface=MIXER,name='ADC Capture Volume'
numid=22,iface=MIXER,name='Class D SPK Ratio Control'
numid=25,iface=MIXER,name='DAC IF1 Data Switch'
numid=27,iface=MIXER,name='DAC IF2 Data Switch'
numid=103,iface=MIXER,name='DAC L2 Mux'
numid=107,iface=MIXER,name='DAC MIXL INF1 Switch'
numid=106,iface=MIXER,name='DAC MIXL Stereo ADC Switch'
numid=105,iface=MIXER,name='DAC MIXR INF1 Switch'
numid=104,iface=MIXER,name='DAC MIXR Stereo ADC Switch'
numid=102,iface=MIXER,name='DAC R2 Mux'
numid=10,iface=MIXER,name='DAC1 Playback Volume'
numid=9,iface=MIXER,name='DAC2 Playback Switch'
numid=108,iface=MIXER,name='DAI select'
numid=88,iface=MIXER,name='DIG MIXL DAC L1 Switch'
numid=89,iface=MIXER,name='DIG MIXL DAC L2 Switch'
numid=86,iface=MIXER,name='DIG MIXR DAC R1 Switch'
numid=87,iface=MIXER,name='DIG MIXR DAC R2 Switch'
numid=23,iface=MIXER,name='DMIC Switch'
numid=37,iface=MIXER,name='Ext Spk L Switch'
numid=38,iface=MIXER,name='Ext Spk R Switch'
numid=3,iface=MIXER,name='HP Playback Switch'
numid=4,iface=MIXER,name='HP Playback Volume'
numid=50,iface=MIXER,name='HPO MIX DAC1 Switch'
numid=49,iface=MIXER,name='HPO MIX DAC2 Switch'
numid=51,iface=MIXER,name='HPO MIX HPVOL Switch'
numid=36,iface=MIXER,name='Headset Mic Switch'
numid=111,iface=MIXER,name='IF2 ADC L Mux'
numid=110,iface=MIXER,name='IF2 ADC R Mux'
numid=17,iface=MIXER,name='IN Capture Volume'
numid=13,iface=MIXER,name='IN1 Boost'
numid=12,iface=MIXER,name='IN1 Mode Control'
numid=15,iface=MIXER,name='IN2 Boost'
numid=14,iface=MIXER,name='IN2 Mode Control'
numid=39,iface=MIXER,name='Int Mic Switch'
numid=45,iface=MIXER,name='LOUT MIX DAC L1 Switch'
numid=46,iface=MIXER,name='LOUT MIX DAC R1 Switch'
numid=47,iface=MIXER,name='LOUT MIX OUTVOL L Switch'
numid=48,iface=MIXER,name='LOUT MIX OUTVOL R Switch'
numid=29,iface=MIXER,name='LPE IHF mixer'
numid=30,iface=MIXER,name='LPE headset mixer'
numid=6,iface=MIXER,name='OUT Channel Switch'
numid=69,iface=MIXER,name='OUT MIXL BST1 Switch'
numid=68,iface=MIXER,name='OUT MIXL BST3 Switch'
numid=74,iface=MIXER,name='OUT MIXL DAC L1 Switch'
numid=73,iface=MIXER,name='OUT MIXL DAC L2 Switch'
numid=72,iface=MIXER,name='OUT MIXL DAC R2 Switch'
numid=70,iface=MIXER,name='OUT MIXL INL Switch'
numid=71,iface=MIXER,name='OUT MIXL REC MIXL Switch'
numid=62,iface=MIXER,name='OUT MIXR BST1 Switch'
numid=61,iface=MIXER,name='OUT MIXR BST2 Switch'
numid=60,iface=MIXER,name='OUT MIXR BST3 Switch'
numid=65,iface=MIXER,name='OUT MIXR DAC L2 Switch'
numid=67,iface=MIXER,name='OUT MIXR DAC R1 Switch'
numid=66,iface=MIXER,name='OUT MIXR DAC R2 Switch'
numid=63,iface=MIXER,name='OUT MIXR INR Switch'
numid=64,iface=MIXER,name='OUT MIXR REC MIXR Switch'
numid=5,iface=MIXER,name='OUT Playback Switch'
numid=7,iface=MIXER,name='OUT Playback Volume'
numid=138,iface=MIXER,name='RECMIXL BST1 Switch'
numid=137,iface=MIXER,name='RECMIXL BST2 Switch'
numid=136,iface=MIXER,name='RECMIXL BST3 Switch'
numid=134,iface=MIXER,name='RECMIXL HPOL Switch'
numid=135,iface=MIXER,name='RECMIXL INL Switch'
numid=139,iface=MIXER,name='RECMIXL OUT MIXL Switch'
numid=132,iface=MIXER,name='RECMIXR BST1 Switch'
numid=131,iface=MIXER,name='RECMIXR BST2 Switch'
numid=130,iface=MIXER,name='RECMIXR BST3 Switch'
numid=128,iface=MIXER,name='RECMIXR HPOR Switch'
numid=129,iface=MIXER,name='RECMIXR INR Switch'
numid=133,iface=MIXER,name='RECMIXR OUT MIXR Switch'
numid=28,iface=MIXER,name='Register Control'
numid=109,iface=MIXER,name='SDI select'
numid=82,iface=MIXER,name='SPK MIXL DAC L1 Switch'
numid=83,iface=MIXER,name='SPK MIXL DAC L2 Switch'
numid=81,iface=MIXER,name='SPK MIXL INL Switch'
numid=84,iface=MIXER,name='SPK MIXL OUT MIXL Switch'
numid=80,iface=MIXER,name='SPK MIXL REC MIXL Switch'
numid=77,iface=MIXER,name='SPK MIXR DAC R1 Switch'
numid=78,iface=MIXER,name='SPK MIXR DAC R2 Switch'
numid=76,iface=MIXER,name='SPK MIXR INR Switch'
numid=79,iface=MIXER,name='SPK MIXR OUT MIXR Switch'
numid=75,iface=MIXER,name='SPK MIXR REC MIXR Switch'
numid=59,iface=MIXER,name='SPOL MIX BST1 Switch'
numid=56,iface=MIXER,name='SPOL MIX DAC L1 Switch'
numid=55,iface=MIXER,name='SPOL MIX DAC R1 Switch'
numid=58,iface=MIXER,name='SPOL MIX SPKVOL L Switch'
numid=57,iface=MIXER,name='SPOL MIX SPKVOL R Switch'
numid=54,iface=MIXER,name='SPOR MIX BST1 Switch'
numid=52,iface=MIXER,name='SPOR MIX DAC R1 Switch'
numid=53,iface=MIXER,name='SPOR MIX SPKVOL R Switch'
numid=32,iface=MIXER,name='SSP BT Master Mode'
numid=34,iface=MIXER,name='SSP Modem Master Mode'
numid=33,iface=MIXER,name='SSP VOIP Master Mode'
numid=31,iface=MIXER,name='SST Probe Byte Control'
numid=16,iface=MIXER,name='Speaker Boost'
numid=1,iface=MIXER,name='Speaker Playback Switch'
numid=2,iface=MIXER,name='Speaker Playback Volume'
numid=125,iface=MIXER,name='Stereo ADC L1 Mux'
numid=127,iface=MIXER,name='Stereo ADC L2 Mux'
numid=118,iface=MIXER,name='Stereo ADC MIXL ADC1 Switch'
numid=119,iface=MIXER,name='Stereo ADC MIXL ADC2 Switch'
numid=116,iface=MIXER,name='Stereo ADC MIXR ADC1 Switch'
numid=117,iface=MIXER,name='Stereo ADC MIXR ADC2 Switch'
numid=124,iface=MIXER,name='Stereo ADC R1 Mux'
numid=126,iface=MIXER,name='Stereo ADC R2 Mux'
numid=101,iface=MIXER,name='Stereo DAC MIXL ANC Switch'
numid=99,iface=MIXER,name='Stereo DAC MIXL DAC L1 Switch'
numid=100,iface=MIXER,name='Stereo DAC MIXL DAC L2 Switch'
numid=98,iface=MIXER,name='Stereo DAC MIXR ANC Switch'
numid=96,iface=MIXER,name='Stereo DAC MIXR DAC R1 Switch'
numid=97,iface=MIXER,name='Stereo DAC MIXR DAC R2 Switch'
alsa_amixer -c 2 cget numid=2 // 从card2 取得主喇叭当时的音量
alsa_amixer -c 2 cset numid=2 39 // 从card2设置主喇叭的音量＝39
alsa_amixer -c 2 cset numid=2 100% // 从card2设置主喇叭的音量＝39