Linux ALSA音频工具aplay、arecord、amixer的使用方法

ALSA 是Advanced Linux Sound Architecture的缩写，先进的Linux音频架构，为Linux操作系统提供音频和MIDI功能。

aplay命令

aplay是播放命令。

root@imx6ul7d:~# aplay -h
Usage: aplay [OPTION]... [FILE]...-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
-s, --samples=#         interrupt after # samples per channel
-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
-i, --interactive       allow interactive operation from stdin
-m, --chmap=ch1,ch2,..  Give the channel map to override or follow--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 coefficient 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 recordedfor this many seconds--process-id-file   write the process ID here--use-strftime      apply the strftime facility to the output file name--dump-hw-params    dump hw_params of the device--fatal-errors      treat all errors as fatal
Recognized sample formats are: S8 U8 S16_LE S16_BE U16_LE U16_BE S24_LE S24_BE U24_LE U24_BE S32_LE S32_BE U32_LE U32_BE FLOAT_LE FLOAT_BE FLOAT64_LE FLOAT64_BE IEC958_SUBFRAME_LE IEC958_SUBFRAME_BE MU_LAW A_LAW IMA_ADPCM MPEG GSM S20_LE S20_BE U20_LE U20_BE SPECIAL S24_3LE S24_3BE U24_3LE U24_3BE S20_3LE S20_3BE U20_3LE U20_3BE S18_3LE S18_3BE U18_3LE U18_3BE G723_24 G723_24_1B G723_40 G723_40_1B DSD_U8 DSD_U16_LE DSD_U32_LE DSD_U16_BE DSD_U32_BE
Some of these may not be available on selected hardware
The available format shortcuts are:
-f cd (16 bit little endian, 44100, stereo)
-f cdr (16 bit big endian, 44100, stereo)
-f dat (16 bit little endian, 48000, stereo)

-t， 指定输出数据格式，默认是wave格式，还支持raw，voc，au，后两种格式不懂。
-D，指定播放设备，设备名的格式为hw:0,0，表示0号card的0号device。
-c，指定channel数。
-f， 指定语音数据格式，有很多格式可以选择。
-r， 指定采样频率，例如5512/8000/11025/16000/22050/32000/44100/48000/64000/88200/96000/176400/192000。
-d，指定播放的时长，单位秒。
-l， 播放设备列表
 

实例
罗列播放设备。

root@imx6ul7d:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: wm8962audio [wm8962-audio], device 0: HiFi wm8962-0 [HiFi wm8962-0]Subdevices: 1/1Subdevice #0: subdevice #0
card 0: wm8962audio [wm8962-audio], device 1: HiFi-ASRC-FE (*) []Subdevices: 1/1Subdevice #0: subdevice #0
root@imx6ul7d:~#

 
播放音频文件。其中-Dhw:0,0 表示card0，device0，对应到aplay -l命令中的设备列表； -d 5表示播放5秒。

root@imx6ul7d:~# aplay -Dhw:0,0 -d5 /unit_tests/ASRC/audio8k16S.wav
Playing WAVE '/unit_tests/ASRC/audio8k16S.wav' : Signed 16 bit Little Endian, Rate 8000 Hz, Stereo
root@imx6ul7d:~#

 
 

arecord 命令

arecord是录音命令。

root@imx6ul7d:~# arecord -h
Usage: arecord [OPTION]... [FILE]...-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
-s, --samples=#         interrupt after # samples per channel
-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
-i, --interactive       allow interactive operation from stdin
-m, --chmap=ch1,ch2,..  Give the channel map to override or follow--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 coefficient 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 recordedfor this many seconds--process-id-file   write the process ID here--use-strftime      apply the strftime facility to the output file name--dump-hw-params    dump hw_params of the device--fatal-errors      treat all errors as fatal
Recognized sample formats are: S8 U8 S16_LE S16_BE U16_LE U16_BE S24_LE S24_BE U24_LE U24_BE S32_LE S32_BE U32_LE U32_BE FLOAT_LE FLOAT_BE FLOAT64_LE FLOAT64_BE IEC958_SUBFRAME_LE IEC958_SUBFRAME_BE MU_LAW A_LAW IMA_ADPCM MPEG GSM S20_LE S20_BE U20_LE U20_BE SPECIAL S24_3LE S24_3BE U24_3LE U24_3BE S20_3LE S20_3BE U20_3LE U20_3BE S18_3LE S18_3BE U18_3LE U18_3BE G723_24 G723_24_1B G723_40 G723_40_1B DSD_U8 DSD_U16_LE DSD_U32_LE DSD_U16_BE DSD_U32_BE
Some of these may not be available on selected hardware
The available format shortcuts are:
-f cd (16 bit little endian, 44100, stereo)
-f cdr (16 bit big endian, 44100, stereo)
-f dat (16 bit little endian, 48000, stereo)

-t，指定输出数据格式，默认是wave格式，还支持raw，voc，au，后两种格式不懂。
-D，指定record设备，设备名的格式为hw:0,0，表示0号card的0号device。
-c，指定channel数，默认是mono，即one channel，最大可以到32。但实际上，如果只有一个麦克风，就只能录制mono音轨。
-f，指定语音数据格式，有很多格式可以选择，例如S8 U8 S16_LE S16_BE U16_LE U16_BE…。
-r，指定采样频率，例如5512/8000/11025/16000/22050/32000/44100/48000/64000/88200/96000/176400/192000。
-d，指定录音的时长。
-vv，在命令行录音的时候使用，可以看到一个由#符号组成的横向的实时音量显示。
 
实例
罗列录音设备。

root@imx6ul7d:~# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: wm8962audio [wm8962-audio], device 0: HiFi wm8962-0 [HiFi wm8962-0]Subdevices: 1/1Subdevice #0: subdevice #0
card 0: wm8962audio [wm8962-audio], device 1: HiFi-ASRC-FE (*) []Subdevices: 1/1Subdevice #0: subdevice #0
root@imx6ul7d:~#

 
一边录音，一边播放。其中 -d5表示录音5秒，-Dhw0,0表示card0，device0；r48000表示采样率是48000；-c2表示两声道；-fS16_LE表示数据格式是S16_LE；-traw表示录音是raw文件。

root@imx6ul7d:~# arecord -d5 -Dhw:0,0 -r48000 -c2 -fS16_LE -traw | aplay -Dhw:0,0 -r48000 -c2 -fS16_LE
Recording raw data 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing raw data 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
root@imx6ul7d:~#

 
aplay和arecord其他参考命令

root@imx6ul7d:~# arecord | aplay

用上面的命令，你就能感知到默认情况的input delay，感觉大概半秒多钟。如果这样：

root@imx6ul7d:~# arecord --period-size 128 | aplay -B 10

就几乎感觉不到延迟。以上两种情况，区别非常明显。
 
查看系统语音设备：

root@imx6ul7d:~# cat /proc/asound/cards0 [wm8962audio    ]: wm8962-audio - wm8962-audiowm8962-audio
root@imx6ul7d:~#

 
 

amixer命令

amixer用于配置音频的各个参数。

root@imx6ul7d:~# amixer -h
Usage: amixer <options> [command]Available options:-h,--help       this help-c,--card N     select the card-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 sequentially-R,--raw-volume Use the raw value (default)-M,--mapped-volume Use the mapped volumeAvailable commands:scontrols       show all mixer simple controlsscontents       show contents of all mixer simple controls (default command)sset sID P      set contents for one mixer simple controlsget sID        get contents for one mixer simple controlcontrols        show all controls for given cardcontents        show contents of all controls for given cardcset cID P      set control contents for one controlcget cID        get control contents for one controlAvailable advanced commands:sevents         show the mixer events for simple controlsevents          show the mixer events for controls
root@imx6ul7d:~#

 
alsamixer命令可以获取图形化界面，通过方向键来设置对应参数。如下所示。

root@imx6ul7d:~# alsamixer

 
 
除了图形化模式，我们还可以用命令行模式。首先查看一下contents，如下。

root@imx6ul7d:~# amixer contents
numid=124,iface=CARD,name='Headphone Jack'; type=BOOLEAN,access=r-------,values=1: values=on
numid=29,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=0
numid=30,iface=MIXER,name='Headphone Mixer Switch'; type=BOOLEAN,access=rw------,values=2: values=off,off
numid=28,iface=MIXER,name='Headphone ZC Switch'; type=BOOLEAN,access=rw------,values=2: values=off,off
numid=27,iface=MIXER,name='Headphone Switch'; type=BOOLEAN,access=rw------,values=2: values=on,on
numid=26,iface=MIXER,name='Headphone Volume'; type=INTEGER,access=rw---R--,values=2,min=0,max=127,step=0: values=93,93| dBscale-min=-121.00dB,step=1.00dB,mute=1
numid=24,iface=MIXER,name='ADC High Performance Switch'; type=BOOLEAN,access=rw------,values=1: values=on
numid=21,iface=MIXER,name='ADC L/R Swap Switch'; type=BOOLEAN,access=rw------,values=1: values=off
numid=23,iface=MIXER,name='ADC Monomix Switch'; type=BOOLEAN,access=rw------,values=1: values=on
numid=14,iface=MIXER,name='Capture HPF Cutoff'; type=INTEGER,access=rw------,values=1,min=0,max=7,step=0: values=0
numid=13,iface=MIXER,name='Capture HPF Mode'; type=ENUMERATED,access=rw------,values=1,items=2; Item #0 'Hi-fi'; Item #1 'Application': values=0
numid=12,iface=MIXER,name='Capture HPF Switch'; type=BOOLEAN,access=rw------,values=1: values=on
... ...

 
根据contents中的内容，可以用cget或cset读取设置参数。
查看获取某个设置项的值用amixer cget +控制参数
根据控制参数类型设置控制参数使用amixer cset +控制参数+" "+参数

以contents中的第二项为例来演示cget和cset。
 
 
读取耳机的音量为7。

root@imx6ul7d:~# amixer cget numid=29,iface=MIXER,name='Headphone Aux Volume'
numid=29,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=0
root@imx6ul7d:~#

 
设置耳机的音量为5。

root@imx6ul7d:~# amixer cset numid=29,iface=MIXER,name='Headphone Aux Volume' 5
numid=29,iface=MIXER,name='Headphone Aux Volume'; type=INTEGER,access=rw---R--,values=2,min=0,max=7,step=0: values=5,5| dBscale-min=-7.00dB,step=1.00dB,mute=0
root@imx6ul7d:~#

 
cget/cset命令在controls、cset cID P、cget cID亦适用。
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
cget cID get control contents for one control

类似的，还有另外一套sget/sset系列的命令：
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
sget sID get contents for one mixer simple control
 
也是同样做法，例如用scontents查看有哪些参数可以控制：

root@imx6ul7d:~# amixer scontents
Simple mixer control 'Headphone',0Capabilities: volume pswitchPlayback channels: Front Left - Front RightCapture channels: Front Left - Front RightLimits: 0 - 127Front Left: 93 [73%] [-28.00dB] Playback [on]Front Right: 93 [73%] [-28.00dB] Playback [on]
Simple mixer control 'Headphone Aux',0Capabilities: volumePlayback channels: Front Left - Front RightCapture channels: Front Left - Front RightLimits: 0 - 7Front Left: 7 [100%] [0.00dB]Front Right: 7 [100%] [0.00dB]
Simple mixer control 'Headphone Mixer',0Capabilities: pswitchPlayback channels: Front Left - Front RightMono:Front Left: Playback [off]Front Right: Playback [off]
... ...

 
同理，scontents的项目用sget和sset配置。

root@imx6ul7d:~# amixer sget 'Headphone',0
Simple mixer control 'Headphone',0Capabilities: volume pswitchPlayback channels: Front Left - Front RightCapture channels: Front Left - Front RightLimits: 0 - 127Front Left: 93 [73%] [-28.00dB] Playback [on]Front Right: 93 [73%] [-28.00dB] Playback [on]
root@imx6ul7d:~#

 
如果想要修改对应设置，用amixer sset ，具体用法是：
amixer sset sID(控制字符串) P(支持的某个值)
其中sID，就是上面的Simple mixer control后面的那个字符串，比如’Headphone’,0
而对其设置就是，先看看其提供了哪些供你设置的值：

root@imx6ul7d:~# amixer sset 'Headphone',0 100
Simple mixer control 'Headphone',0Capabilities: volume pswitchPlayback channels: Front Left - Front RightCapture channels: Front Left - Front RightLimits: 0 - 127Front Left: 100 [79%] [-21.00dB] Playback [on]Front Right: 100 [79%] [-21.00dB] Playback [on]
root@imx6ul7d:~#

 
 

参考资料

https://www.cnblogs.com/cslunatic/p/3227655.html
https://cs.pynote.net/sf/linux/shell/202207131/