[pulseaudio-discuss] No audio heard from loopback

[Arun Raghavan]

On Tue, 2011-09-27 at 00:05 +0530, Sriram Gopalan wrote:
> Hello everybody, 
> We are facing an issue with loopback in pulse audio 0.9.22. We
> recently ported pulseaudio to an ARM 11 based evaluation board and are
> running pulseaudio in system mode. The application being targeted is
> In-vehicle-Infotainment and the board has a Mono Mic ( 16-bit, 1
> channel) and a Stereo Speaker ( 2 channels, 16-bit, 44.1 Khz). 
> 
> 
> 1) With gstreamer we are able to playback audio to the speakers using
> the following command. pulseaudio promptly gets into action and plays
> the file at 44.1 Khz without a glitch - 
> #gst-launch filesrc location=/home/test/songs/test.mp3 ! mad !
> alsasink
> 
> 
> 2) When we do a capture with the mic using the command below, again it
> works fine ( By default arecord and aplay use 8Khz, 8-bit mono channel
> for capture and playback) - 
> #arecord test.wav
> #aplay test.wav
> 
> 
> 3) However, when we attempt the followings, it does not work. We
> cannot hear any audio, whereas the same works on my Ubuntu 10.10
> desktop
> #arecord | aplay
> #gst-launch alsasrc ! alsasink
> #pactl load-module module-loopback

Incidentally, why are all the tests with alsasrc/alsasink and not
pulsesrc/pulsesink?

-- Arun