PulseAudio

General Information

Command Line (for testing)

/usr/bin/pulseaudio --system --disallow-exit --disable-shm --exit-idle-time=-1 -vvvvvv --log-level=debug --verbose

Sinks (Outputs), Sources (Inputs), Input-Sinks ("Connectors")

Sinks: Equivalent to Speaker Out, Line Out, Head Phone Jacks, etc.

Sources: Equivalent to Microphone, Line In, etc.

Input-Sinks: Equivalent to wires connecting Sources to Sinks internally via Software

Fun Facts and Observations

Sink-Inputs

Example 1;

System.pa Configuration (AKA "Circumstances");

load-module module-native-protocol-unix

load-module module-alsa-sink device=surround51:CARD=ICUSBAUDIO7D,0 sink_name=alsa_output.0.surround.51

Commands: pactl list sinks short , pactl list sources short , and pactl list sink-inputs short

pactl list sinks short
1       alsa_output.0.surround.71       module-alsa-sink.c      s16le 8ch 48000Hz       IDLE

pactl list sources short
1       alsa_output.0.surround.71.monitor       module-alsa-sink.c      s16le 8ch 48000Hz       IDLE

pactl list sink-inputs short
...just for clarity, the output from the above command was blank / nothing.

Example 2;

System.pa Configuration (AKA "Circumstances");

load-module module-native-protocol-unix

load-module module-alsa-sink device=surround51:CARD=ICUSBAUDIO7D,0 sink_name=alsa_output.0.surround.51
load-module module-alsa-source device=hw:0,0 source_name=alsa_input.0.analog-stereo
load-module module-loopback source=alsa_input.0.analog-stereo sink=alsa_output.0.surround.51 latency_msec=800

Play a file using MPD / MPC or "PulseAudio Play": paplay --device=alsa_output.0.surround.51 BeeGees.wav Commands: pactl list sinks short , pactl list sources short , and pactl list sink-inputs short

pactl list sinks short
1       alsa_output.0.surround.71       module-alsa-sink.c      s16le 8ch 48000Hz       IDLE

pactl list sources short
1       alsa_output.0.surround.71.monitor       module-alsa-sink.c      s16le 8ch 48000Hz       IDLE

pactl list sink-inputs short
4       1       10      protocol-native.c       s24-32le 2ch 44100Hz
(previous output from other USB Audio Device: 2       1       5       protocol-native.c       s16le 2ch 44100Hz)

*Note(s): If using paplay, another SSH session must be used for the pactl command. If using MPC, once started play can be stopped and the MPD Daemon will maintain the existence of the 'protocol-native.c' sink-inputs.

0       1       -       module-loopback.c       s16le 2ch 48000Hz
2       1       5       protocol-native.c       s16le 2ch 44100Hz