[FFmpeg-user] Fwd: Cannot capture audio in screen recording

Joel Roth joelz at pobox.com
Wed Sep 12 08:57:25 EEST 2018

On Tue, Sep 11, 2018 at 02:03:06PM +0200, Moritz Barsnick wrote:
> On Tue, Sep 11, 2018 at 15:46:11 +0530, Abhijit Nathwani wrote:
> > > Could it be that your ALSA capture device's recording is muted?
> > I don't know. How to ensure that?
> ALSA's command line tools' syntax is truly difficult (PITA, if you know
> what the term means). You can use the command "amixer" to display the
> present state. You can use a "GUI" (ncurses) program such as
> "alsamixer" to graphically display all ports' states. Some may show
> "[off]". You need to switch the recording port "[on]". I used to do
> this with "amixer" or possibly "alsactl", when I was still using ALSA
> directly, but it took me days to figure out the syntax. My notes say I
> did something like this:
> $ amixer eset 'Input Gain Switch',0,Switch2 on
> $ amixer eset 'Line Switch',0,Switch2 capture
> $ amixer eset 'Input Gain Volume',0,Volume1 9
> Modern ALSA or newer frontends may be nicer.

The command

alsactl init

will set reasonable defaults on the sound device. 

Alsamixer is quirky. I recently discovered qasmixer,
which seems to have been designed with care. 


Joel Roth

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