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* System audio recording have very low amplitude
@ 2020-07-29  9:39 Ariel Elkin
  2020-07-29 20:04 ` Jeremy Nicoll - ml sox users
  0 siblings, 1 reply; 4+ messages in thread
From: Ariel Elkin @ 2020-07-29  9:39 UTC (permalink / raw)
  To: sox-users


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Hello,

I’m using sox to record the audio produced by the system (i.e. from the OS and other running apps), but the recordings sound very quiet.

I first create a virtual input/output device using Blackhole (https://github.com/ExistentialAudio/BlackHole/ <https://github.com/ExistentialAudio/BlackHole/>) or Loopback (https://rogueamoeba.com/loopback/ <https://rogueamoeba.com/loopback/>). I then start playback of a file using iTunes, and start recording thus:

rec --rate 44100 --channels 2 --no dither test-output.aiff

(Note that this spits out the following error messages:
rec WARN formats: can't set sample rate 44100; using 48000
rec WARN formats: can't set 2 channels; using 16

However, test-output.aiff ends up being a stereo file at 44.1 kHz)

test-output.aiff properly records system audio, but the mean amplitude is about half the mean amplitude of the original sounds I played back. 

Any thoughts? 

Thanks

Ariel

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^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: System audio recording have very low amplitude
@ 2020-07-30 13:30 Ariel Elkin
  2020-07-30 15:01 ` Måns Rullgård
  0 siblings, 1 reply; 4+ messages in thread
From: Ariel Elkin @ 2020-07-30 13:30 UTC (permalink / raw)
  To: sox-users

> What OS are you using? (I see from those links that the apps are MacOS, which I know nothing about. Someone else might do; also what version?)

I’m using macOS 10.15

> Does MacOS have an internal audio mixer that determines the levels of sound from various apps and how they go to other devices?
No exactly, but there’s an app (Audio MIDI Setup) which will allow you to set the input/output volume and sample rate of your audio hardware. I’ve checked there already and ensured that the input/output volume of Loopback and BlackHole were at 1.

Can someone clarify if this command

rec test-output.aiff 

could do any implicit gain attenuation? It’s not clear from the documentation.

Thanks

Ariel

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^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2020-07-30 15:01 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-29  9:39 System audio recording have very low amplitude Ariel Elkin
2020-07-29 20:04 ` Jeremy Nicoll - ml sox users
2020-07-30 13:30 Ariel Elkin
2020-07-30 15:01 ` Måns Rullgård

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