[libav-tools] need help defining audio stream inputs to avconv

Dave davestechshop at gmail.com
Wed Aug 28 00:31:40 CEST 2013


see below


On Tue, Aug 27, 2013 at 5:48 PM, Luca Barbato <lu_zero at gentoo.org> wrote:

> On 25/08/13 18:09, Dave wrote:
> > Hi. The command `pacmd list-cards` lists two sources on audio card 1.
> They
> > are shown below.
> >
> > I need help defining these two sources as inputs to avconv.
> >
> >    1.
> alsa_output.usb-Focusrite_Scarlett_2i2_USB-00-USB.analog-stereo.monitor/#2:
> >    Monitor of Scarlett 2i2 USB Analog Stereo
> >    2. alsa_input.usb-Focusrite_Scarlett_2i2_USB-00-USB.analog-stereo/#3:
> >    Scarlett 2i2 USB Analog Stereo
> >
> > My goals is to create a single audio file that contains the stream from
> > these two sources where they remain synced and one source is one track
> > (e.g., left) and the other source is the other track (e.g., right). (I'm
> > recording interviews for podcasting; one side of the conversation is more
> > important than the other so separate tracks can help editing.)
> >
> > My first *guess* about how to do this is this simple script:
> >
> > #!/bin/bash
> > OUTPUT="audio_`date +%Y-%m-%d_%H%M`"
> > avconv \
> > -f alsa -ac 2 -i
> > <alsa_output.usb-Focusrite_Scarlett_2i2_USB-00-USB.analog-stereo.monitor>
> > \
> > -f alsa -ac 1 -i
> > <alsa_input.usb-Focusrite_Scarlett_2i2_USB-00-USB.analog-stereo> \
> > -map 0:0 -map 1:0 \
> > -acodec flac \
> > -threads 0 \
> > -y $OUTPUT
> >
> >
> > I assume I need to replace what is in angle brackets with the correct
> > notation. I have no idea if the rest of the above script is even close...
>
> If you are using pulseaudio, you can use the pulseaudio capture and use
> those names verbatim. The rest doesn't look wrong beside an acodec that
> could be a -c:a
>
> lu
>

Thank you for your reply. I am using pulseaudio. However, I am not familiar
with "pulseaudio control" yet. How would I use it? Would you be so kind as
to take my pseudo code script and show me how it actually should look with
the changes you suggest?

Also any links to references I should read are appreciated. Thanks!
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