Linux---ALSA音频工具arecord、aplay、amixer使用
一、arecord与aplay
1.1 查询Linux系统下设备声卡信息
book:~/code/test$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: AudioPCI [Ensoniq AudioPCI], device 0: ES1371/1 [ES1371 DAC2/ADC]
Subdevices: 1/1
Subdevice #0: subdevice #0
1.2 录制音频
book:~/code/test$ arecord -D hw:0,0 -r 16000 -c 1 -f S16_LE test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 16000 Hz, Mono
^CAborted by signal Interrupt... //这里使用Ctrl+c 结束了录制
book:~/code/test$ ls
test.wav timer_fd_test
录制完成后我们可以看到执行目录生成对应的test.wav 音频文件。
1.3 播放音频
book:~/code/test$ aplay -D hw:0,0 test.wav
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 16000 Hz, Mono
1.4 arecord及aplay参数说明
上面我们看到了arecord及aplay的使用，后面参数的意义可以用- h查询如下图，需要说明的是-D 参数后面hw:card num, device num。
book:~/code/test$ 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
-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 recorded
for 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 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)
二、amixer
amixer命令稍微复杂一点，主要用来设置音频参数的，用法可以用-h查询，基本使用方法为：
amixer controls 用于查看音频系统提供的操作接口
amixer contents 用于查看接口配置参数
amixer cget + 接口函数
amixer cset + 接口函数 + 设置值
book:~/code/test$ 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 volume
Available 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
sget sID get contents for one mixer 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
cget cID get control contents for one control
查询可设置项，command里面controls与controls，scontents与contents类似。
book:~/code/test$ amixer contents
numid=1,iface=MIXER,name='Master Playback Switch'
; type=BOOLEAN,access=rw------,values=1
: values=on
numid=2,iface=MIXER,name='Master Playback Volume'
; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
: values=63,63
| dBscale-min=-94.50dB,step=1.50dB,mute=0
numid=16,iface=MIXER,name='PCM Playback Switch'
; type=BOOLEAN,access=rw------,values=1
: values=on
numid=17,iface=MIXER,name='PCM Playback Volume'
; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
: values=57,57
| dBscale-min=-34.50dB,step=1.50dB,mute=0
numid=8,iface=MIXER,name='Line Playback Switch'
; type=BOOLEAN,access=rw------,values=1
: values=off
... ...
这里我们以查询和设置’Master Playback Volume’为例，进行说明cget cID 和 cset cID P用法，我们将values从默认的63改为50：
book:~/code/test$ amixer cget numid=2,iface=MIXER,name='Master Playback Volume'
numid=2,iface=MIXER,name='Master Playback Volume'
; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
: values=63,63
| dBscale-min=-94.50dB,step=1.50dB,mute=0
book:~/code/test$ amixer cset numid=2,iface=MIXER,name='Master Playback Volume' 50
numid=2,iface=MIXER,name='Master Playback Volume'
; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
: values=50,50
| dBscale-min=-94.50dB,step=1.50dB,mute=0
scontrols查询，sset sID P与sget sID
book:~/code/test$ amixer scontrols
Simple mixer control 'Master',0
Simple mixer control 'PCM',0
Simple mixer control 'Line',0
Simple mixer control 'CD',0
Simple mixer control 'Mic',0
Simple mixer control 'Mic Boost (+20dB)',0
Simple mixer control 'Video',0
Simple mixer control 'Phone',0
Simple mixer control 'IEC958',0
Simple mixer control 'Aux',0
Simple mixer control 'Capture',0
Simple mixer control 'Mix',0
Simple mixer control 'Mix Mono',0
book:~/code/test$ amixer sget 'PCM',0
Simple mixer control 'PCM',0
Capabilities: pvolume pswitch pswitch-joined
Playback channels: Front Left - Front Right
Limits: Playback 0 - 63
Mono:
Front Left: Playback 57 [90%] [51.00dB] [on]
Front Right: Playback 57 [90%] [51.00dB] [on]
book:~/code/test$ amixer sset 'PCM',0 55
Simple mixer control 'PCM',0
Capabilities: pvolume pswitch pswitch-joined
Playback channels: Front Left - Front Right
Limits: Playback 0 - 63
Mono:
Front Left: Playback 55 [87%] [48.00dB] [on]
Front Right: Playback 55 [87%] [48.00dB] [on]