How can I record audio output from command line in Linux?

Question

I want to record the output of audio to an mp3 file. What tools and commands can I use in the Ubuntu Linux terminal?

Answer 1

Other answers suggested the following tools: sox, arecord, and parec. Additionally, PipeWire users may use pw-cat, although the other tools work with PipeWire also. They can all be invoked simply:

arecord

arecord --format=cd file.wav

It saves in .wav by default. If you don't specify a decent format, the default audio quality is poor. One feature I like about this program is its nice vumeter graphical output. It also supports dynamic output filenaming (via hour, minute, day...). Unfortunately, it can't output to ogg or mp3.

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sox

rec file.ext

This program doesn't currently work with zsh completions. It displays a meter in its graphical output, but it displays other information also. It supports mp3 and ogg.

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pacat

parecord file.ext

It supports mp3 and ogg. But it can't display a meter in its graphical output.

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pw-cat

pw-record file.ext

It's pacat for PipeWire. It supports custom quality settings for ogg and mp3, whereas pacat doesn't. It doesn't have a metered graphical output either.

To record from a different audio device, a USB microphone for example, you can use one of the methods listed here to first get the name or nickname of your recording device. For example:

pw-cli list-objects | grep node.nick

Assuming this has yielded "USB Audio Device", we then use that nickname with the --target option:

pw-record --target "USB Audio Device" file.ext

Answer 2

First you need to extract the name of your output device:

To do this, you can install the following packets:

sudo apt-get install pulseaudio-utils lame mpg123

And run:

pacmd list-sinks | grep -e 'name:' -e 'index' -e 'Speakers'

The output could be like this:

index: 1
    name: <alsa_output.pci-0000_00_1b.0.analog-stereo>
        analog-output-speaker: Speakers (priority 10000, latency offset 0 usec, available: unknown)
index: 23
    name: <alsa_output.pci-0000_00_03.0.hdmi-surround71>

After you found the name, you can run the following command to record the output to an mp3 file:

parec -d alsa_output.pci-0000_00_1b.0.analog-stereo.monitor | lame -r -V0 - out.mp3

Or using sox you can do the following, however I found the first solution more robust:

sox -t pulseaudio alsa_output.pci-0000_00_1b.0.analog-stereo.monitor -t mp3 test.mp3 

However, if you want to automatically start and stop recording you can run:

parec -d alsa_output.pci-0000_00_1b.0.analog-stereo.monitor | sox -t raw -b 16 -e signed -c 2 -r 44100 - test.ogg silence 1 0.1 3% 1 3.0 3%

It begins recording when a sound is sent to the speaker and stops if nothing is received after 3 seconds. For more information about sox, refer to its man page for Linux.

Answer 3

Kudos to @Ahmad. This worked for me:

sox -e signed-integer -L -b16 -c2 -r44100 -t raw "|parec -d alsa_output.pci-0000_0c_00.4.iec958-stereo.monitor" -t mp3 -c2 -C 320.01 stream.mp3 silence 1 0.1 3% 1 3.0 3%

where input stream parameters can be seen with pacmd list-sinks:

name: <alsa_output.pci-0000_0c_00.4.iec958-stereo>
sample spec: s16le 2ch 44100Hz
properties:
        alsa.resolution_bits = "16"

Answer 4

You can use arecord for this.

Get your available devices with arecord -l. This will produce something like this:

card 0: PCH [HDA Intel PCH], device 0: CX20590 Analog [CX20590 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Device [USB Audio Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Then, to record using the USB microphone (card 1, subdevice 0) use, for example:

arecord --device="hw:1,0" --format=S16_LE --rate=48 rec_$(date "+%F_%H-%M-%S").wav