Using Pulse to capture from soundcard

[Arun Raghavan]

On Fri, 20 May 2016, at 03:55 AM, Cole Bush wrote:
> I have a raspberry pi with an external soundcard. I am wondering if the
> following pipeline is possible:
> 
> iPod ---> auxiliary cord ---> input of soundcard ---> processing --->
> output of soundcard
> 
> I currently have a pipeline in place that plays from file, displays the
> spectrum, and then outputs to the soundcard. My next step is to replace
> the
> file with input from the soundcard.
> 
> While having music playing on the aux cord, I have run: gst-launch-1.0
> pulsesrc ! audioconvert ! pulsesink . It doesn't fail but i don't hear
> anything.
> 
> Pulse/Alsa land is quite confusing and I am not sure if what I want to do
> is doable while retaining audio quality.

pulsesrc should work if the input levels are correct. There are two
things you need to check:

1. Is pulsesrc using the correct PulseAudio source (pactl list
source-ouputs to see the running capture streams, and pactl list sources
to see the available capture sources)

2. Is the source volume high enough (pactl list sources will show you
the capture source volume)

-- Arun