[pulseaudio-discuss] sound volume for recording

Istvan Gabor suseuser04 at freemail.hu
Wed Sep 21 18:05:34 UTC 2016

Tanu Kaskinen írta:
>On Sat, 2016-09-17 at 13:53 +0200, Istvan Gabor wrote:
>> Hello:
>> I record sound from flash stream using pulseaudio.
>> This is the command I use for recording sound:
>> pacat --record -d alsa_output.pci-0000_00_06.0.analog-stereo.monitor
>> | sox -t raw -r 44100 -s -L -b 16 -c 2 - "output.wav".
>> I use pavucontrol to control sound volumes for recording and playing
>> the sound.
>> In playback tab: ALSA plugin volume; in Recording tab: pacat: pacat
>> from Monitor of Built-in Audio Analog Stereo; in Output devices tab:
>> Built-in Audio Analog Stereo Port: Line Out (plugged in).
>> The problem is when I change the output volume in the output tab
>> (Output devices tab: Built-in Audio Analog Stereo Por) it changes the
>> recording volume too, therefore I can't change the listening volume
>> level when I record sound.
>> How could I make recording volume independent from the output volume
>> I listen to?
>Maybe this would work:

Thank your for your answer.

>pactl load-module module-virtual-sink sink_name=pizza master=alsa_output.pci-0000_00_06.0.analog-stereo use_volume_sharing=false
>That will load a virtual sink that forwards the audio to the alsa sink.
>The virtual sink will have its own monitor source that isn't affected
>by the alsa sink volume.

I see. I did it.

>Move the flash stream to the pizza sink and record from pizza.monitor,
>and when you need to change the output volume, use the alsa sink for

OK, I moved the stream to pizza as follows:

Get the alsa plugin/flash stream index by:

pacmd list-sink-inputs
2 sink input(s) available.
    index: 2
    sink: 0 <alsa_output.pci-0000_00_1b.0.analog-stereo>

That is I have to move index 2 to pizza:
pactl move-sink-input 2 pizza

Now I have 2 playbacks: virtual sink stream and alsa-plugin, and I have two outputs: line-out (plugged in) and virtual sink pizza.

I can record from pizza.monitor:

pacat --record -d pizza.monitor | sox -t raw -r 44100 -s -L -b 16 -c 2 - "output.wav"

Now I can change line out output volume without affecting recording volume.

That's what I wanted. Thanks!

I have another question:

I am puzzled by stream/sink names in pavucontrol window.

For example in the playback tab I have:

Virtual Sink Stream from Virtual Sink pizza on Built-in Audio Analog Stereo on _Built-in_Audio_Analog_Stereo_


ALSA plug-in [plugin container]: ALSA Playback on _Virtual_Sink_pizza_on_Built-in_Audio_Analog_Stereo_

The underlined parts are in a button on the right.

What do these definitions/descriptions exactly mean?



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