[pulseaudio-discuss] Routing to/from HE910 cell modem w/echo cancellation

[Peter Barada]

All,

I'm a bit unclear on how to use paplay/parecord as replacements for
aplay/arecord.

On my dm3730-based system I have an HE910 modem hooked up and have
created a snd-soc device for it (using the snd-soc-dummy-dai) to move
data in/out of the HE910 PCM port.  My alsa devices show up as:

root at lv5000:~# aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
default:CARD=omap3beagle
    omap3beagle,
    Default Audio Device
sysdefault:CARD=omap3beagle
    omap3beagle,
    Default Audio Device
default:CARD=omap3he910
    omap3he910,
    Default Audio Device
sysdefault:CARD=omap3he910
    omap3he910,
    Default Audio Device

Where omap3beagle source is the microphone and its sink is the speaker,
omap3he910 source is PCM data from the HE910 and its sink is PCM data to
the HE910.

Previously I'd setup two pipes using aplay/arecord to move the data
to/from the microphone to the HE910 and take the HE910 data coming back
and play on the speaker via:

arecord -f S16_LE -r 8000 | aplay -D hw:1,0 &   # microphone -> HE910
arecord -f S16_LE -r 8000 -D hw:1,0 | aplay -D plug:dmix &   # HE910 ->
speaker

I'm attempting the same with pulseaudio (with echo cancellation)
following comments from
http://lists.freedesktop.org/archives/pulseaudio-discuss/2012-December/015685.html 
where:

Microphone: 
alsa_input.platform-omap3beagle-soc-audio.analog-stereo.echo-cancel
Speaker:
alsa_output.platform-omap3beagle-soc-audio.analog-stereo.echo-cancel

data from HE910:  alsa_input.platform-soc-audio.analog-mono
data to HE910: alsa_output.platform-soc-audio.analog-mono

and have setup two loopbacks:

pactl load-module module-loopback
source=alsa_input.platform-omap3beagle-soc-audio.analog-stereo.echo-cancel
rate=8000 sink=alsa_output.platform-soc-audio.analog-mono # microphone
-> HE910
pactl load-module module-loopback
source=alsa_input.platform-soc-audio.analog-mono rate=8000
sink=alsa_output.platform-omap3beagle-soc-audio.analog-stereo.echo-cancel 
# HE910 -> speaker

But at this point I'm not sure how to setup the recording/play to hook
the two together or should these loopbacks run all the time?  Should I
setup two pipes as previously using PA device names and if so, how do I
have parecord send its output to stdout?

Any help is appreciated, thanks in advance!

-- 
Peter Barada
peter.barada at logicpd.com