前几天在嵌入式linux上用到alsa command，网上查的资料多不给力，仅仅有动手一点点查，最终能够用了，将这个用法告诉大家，以免大家少走弯路。
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 的系统支持例如以下 alsa cmd
-rwxr-xr-x root shell 68242 2014-10-08 05:18 alsa_amixer -rwxr-xr-x root shell 67639 2014-10-08 05:18 alsa_aplay -rwxr-xr-x root shell 130323 2014-10-08 05:18 alsa_ctl
不同的系统能够稍有不同，比方有的系统就叫aplay\amixer .....
1.怎样使用alsa_aplay:
alsa_aplay -h //看一下眼下支持哪些使用方法
-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
会有具体的help说明，这个就不说了，能够自己试。 alsa_aplay -l //列出系统有几个声卡（card 0/1/2....）, 及每一个卡的一个设备（device 0/1/2....）
比方我的系统为：
**** 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-aif2-1 [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: cloverviewaudio [cloverview_audio], device 3: BTSCO snd-soc-dummy-dai-3 [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: cloverviewaudio [cloverview_audio], device 4: VOIP rt5640-aif2-4 [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: cloverviewaudio [cloverview_audio], device 5: IFX_MODEM_MIXING snd-soc-dummy-dai-5 [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: cloverviewaudio [cloverview_audio], device 6: virtual-stream rt5640-aif1-6 [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 2: cloverviewaudio [cloverview_audio], device 7: CTP Probe snd-soc-dummy-dai-7 [] Subdevices: 1/1 Subdevice #0: subdevice #0
因为我的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的使用方法
alsa_amixer -h //一样的help,这里不列了。
用alc5640进行mixer控制的使用方法：
# alsa_amixer -c 2 controls
例如以下：
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 获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