Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

I would like to record an output of a program with PulseAudio using command line/bash script. It is important not to record every output of the sound card, but only the one of one specific program. I thought I would have to create a new null-sink and than move the programs output to this new sink. Than tell parec to use this specific monitor to record. The first step would be something like this:

pactl load-module module-null-sink sink_name=steam

But how to move the programs output now to this sink? And how to record the specific sink with a bash script?

share|improve this question

2 Answers 2

up vote 15 down vote accepted

Try something like this:

In a terminal enter

pacmd

(this is the CLI of the PulseAudio-Server) then use

list-sink-inputs

(where you get the indices of the running inputs) Now find the index of your input. Now referred to as $INDEX

the scriptable part is:

pactl load-module module-null-sink sink_name=steam
pactl move-sink-input $INDEX steam
parec -d steam.monitor | oggenc -b 192 -o steam.ogg --raw -

Explanations:

  • The first command will add a null-sink as you already knew.
  • The second command moves the sink-input from your standard-audio-sink to steam
  • The third command records the monitor of the device steam (-d) and puts the output (raw-wave-stream) into oggenc, which encodes this wave-stream to an oga-file. (for mp3 use lame)

Greez Waschtl

share|improve this answer
    
Brilliant, thank you so much for this great answer! :) –  Force Nov 24 '11 at 11:32
1  
can you please explain how to undo this operation? my null sinks are still mapped to various applications, and now i have no sound! –  ixtmixilix Aug 20 '12 at 12:44
    
@ixtmixilix: the easiest way to restore all settings to default is to just kill and restart the pulseaudio server. If set to autospawn (this is the default) you simply issue pulseaudio -k in a terminal. –  Takkat Mar 2 '13 at 19:48
    
@ixtmixilix When you run list-sink-inputs take note of the sink value. To swap back just run pactl move-sink-input $INDEX $SINK. Something like pactl move-sink-input 4719 1 –  Ciaran Feb 21 at 10:28

@Waschtl's answer is fantastic. @ixtmixilix asked about restoring regular audio after the recording is finished. Here's the easiest way I know of:

Install and run the pavucontrol GUI. You should see your audio-outputting application and it's volume meter under the Playback tab in there. There will be a button next to it showing that it's playing on Null Output. Click on that and change it to your ordinary audio output, Built-in Audio Analog Stereo in my case.

Here's a screenshot of what you're looking for:

screenshot

You can also use this approach to set up your recording in the future, after you've run the load-module command in @Waschtl's answer to create the sink.

share|improve this answer
    
If you can, upload a screen-shot in Imgur and link it into your answer. –  Lucio Mar 2 '13 at 19:11
    
Grabbed one, thanks for the suggestion. –  Jack O'Connor Mar 4 '13 at 20:05

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.