查看“How to record with arecord”的源代码

{{DISPLAYTITLE:如何使用arecord录音}}

= 如何使用arecord录音 =

arecord 是ALSA声卡驱动程序的命令行声音文件记录器。 它支持多种文件格式和具有多个设备的多个声卡。 如果以交错模式录制，文件将在2GB文件大小之前自动分割。

使用前先查看 arecord 的帮助信息：
<syntaxhighlight lang# "bash">
[root@imx6ull:~]# 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 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)
</syntaxhighlight>

根据帮助信息可知：
使用 arecord -l 命令列出声卡和数字音频设备：
<syntaxhighlight lang# "bash">
[root@imx6ull:~]# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: wm8960audio [wm8960-audio], device 0: HiFi wm8960-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: wm8960audio [wm8960-audio], device 1: HiFi-ASRC-FE (*) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

</syntaxhighlight>
得到声卡和数字音频设备列表后，可根据其信息进行以下操作：
-d 指定录音时间(秒)
-D 参数用于指定音频设备 PCM
    以 hwx,x 开头(声卡号,设备号)
    根据上面列出的设备,如果选择 HiFi wm8960-hifi-0 来录制声音的话那么 pcm 设备就为 hw0,0,如果是 HiFi wm8960-hifi-1 则 pcm 设备为 hw0,1,HiFi wm8960-hifi-2 则 pcm 设备为 hw0,2 ...以此类推。
-r 指定采样频率: 5512/8000/11025/16000/22050/32000/44100/48000/64000/88200/96000/176400/192000
-f 指定采样格式上面的帮助信息列出了: cd/cdr/dat/S16_LE/S32_LE/...

示例： 
<syntaxhighlight lang# "bash">
[root@imx6ull:~]# arecord -D default:CARD=mcasp0 -d 100000   -f cd -t raw duration—100000s_format-cd.raw
[root@imx6ull:~]# arecord -D default:CARD=mcasp0 -d 100000   -f dat -t raw duration—100000s_format-dat.raw
[root@imx6ull:~]# arecord -D default:CARD=mcasp0 -d 100000   -f S16_LE -r 16000 -t raw duration—100000s_format-S16_LE_rate-16000.raw
[root@imx6ull:~]# arecord -Dhw:0,1 -r8000 -f cd test.wmv
[root@imx6ull:~]# arecord -Dhw:0,0 -r8000 -f S16_LE -c 2 test.wmv 
[root@imx6ull:~]# arecord -Dhw:0,2 -r48000 -f S32_LE -c 2 test.wmv 
</syntaxhighlight>



[[Category:Linux_Operating_System]]
	[[Category:Audio]]
		[[Category:ALSA]]
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