Linux Sound

Contents:

Abreviations
Usefull Commands
Scripts
ALSA - Advanced Linux Sound Architecture
Pulse-Audio
Jack Audio
paprefs
IC7300's USB Devices
Plug-in USB Sound Cards/Devices
How to Switch Audio Device on the Fly
Audacity
Alpha Audio
lv2
Cleanfeed
Dummy Output and system is not playing audio
References

Abreviations

S/PDIF - Sony/Philips Digital Interface. Alternative for HDMI. Used for digital audio.
Connectors are coaxial (RCA) and optical (Toslink).
PCM - Pulse-code modulation is a method used to digitally represent sampled analog signals
https://en.wikipedia.org/wiki/Pulse-code_modulation
LPCM Linear pulse-code modulation is a specific type of PCM where the quantization levels are linearly uniform.

Usefull Commands

inxi -Ax
inxi -Fx
usb-devices
lsusb -v -d <vid>:<pid> | grep -y serial    # Display Serial No if one exists
lsusb -v -s <bus>:<device> | grep -y serial # Display Serial No if one exists
lspci -v | grep  -i audio
aplay -l
arecord -l
amixer
alsamixer       # char based ncurses display
sudo alsactl store CARD # save setting from alsa mixer
sudo alsactl restore    # restore setting from alsa mixer
cat /proc/asound/cards
cat /proc/asound/pcm
pactl list short sources
tree /proc/asound/card0/
/ust/bin/pulseaudio -k pulseaudio --start
/sbin/alsa {unload|reload|force-unload|force-reload|suspend|resume}
cat /dev/urandom | aplay -D hw:n,m   # This will bombard the card with random data. ^D to stop.

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Scripts

#!/bin/bash
# filename: ~/bin/snd-pci-cards.sh
#
echo "PCI Sound cards recognized by the system:"
lspci -nn | grep --color=none '\[04[80][13]\]'
#
echo "PCI Sound cards recognized by ALSA:"
lspci -nn | grep '\[04[80][13]\]' | while read line
do
        lspci -nnk | grep -A 3 '\[04[80][13]\]' | grep -e 'Kernel modules: ..*' -e '\[04[80][13]\]' | grep --color=none -F "$line"
done
#
echo "PCI Sound cards recognized by ALSA, and activated:"
lspci -nn | grep '\[04[80][13]\]' | while read line
do
        lspci -nnk | grep -A 3 '\[04[80][13]\]' | grep -e 'Kernel drivers in use: ..*' -e '\[04[80][13]\]' | grep --color=none -F "$line"
done

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ALSA - Advanced Linux Sound Architecture

aplay -l
alsamixer 		# F6 to select card
alsamixer -c2	# start with card 2 selected
# "M" to unmute
#
apt install pavucontrol
Change default sound card settings with a .asoundrc config file
vi .asoundrc # set default sound card
#
vi /usr/share/pulseaudio/alsa-mixer/paths/analog-output-lineout.conf
pulseaudio -k
pulseaudio --start

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Pulse-Audio

To direct microphone to the speakers:
The way I learned the name of the output device (sink) and input device (source) was to use these 2 commands:

pacmd "list-sinks"          # Speakers
pacmd "list-sources"        # Microphones

Create a loopback - P.A.type system:

pactl load-module module-loopback latency_msec=1	Mic to Speakers
pactl unload-module module-loopback		        Mic disconnect

To apply echo cancellation:

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Jack Audio

JACK Audio Connection Kit:
https://jackaudio.org/applications/

Working with Internal Audio Routing:
https://music.tutsplus.com/series/working-with-internal-audio-routing--audio-21859

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paprefs

PulseAudio Preferences (paprefs) is a simple GTK based configuration dialog for the PulseAudio sound server. Please note that this program can only configure local servers, and requires that a special module module-gsettings is loaded in the sound server.
apt install paprefs

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IC7300's USB Devices

lsusb
Bus 001 Device 068: ID 08bb:2901 Texas Instruments PCM2901 Audio Codec
Bus 001 Device 067: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP2102/CP2109 UART Bridge Controller [CP210x family]
Bus 001 Device 066: ID 0451:2046 Texas Instruments, Inc. TUSB2046 Hub

The IC7300's USB interface has the following devices:

The PCM2901/2903 is TI's single-chip Stereo USB1.1 stereo audio CODEC with USB-compliant full-speed
protocol controller (and S/PDIF only on PCM2903). On-chip analog PLLs with SpAct enable playback
and record with low clock jitter and with independent playback and record sampling rates.
http://www.ti.com/product/PCM2901
The CP2102 chip is a single chip USB to UART bridge IC. The CP2102 can be used to migrate legacy serial
port based devices to USB. Cygnal Integrated Products, Inc. has bben acquired by Silicon Laboratories.
https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers
The TUSB2046x is a 3.3-V CMOS hub device that provides one upstream port and four downstream
ports in compliance with the Universal Serial Bus (USB) specification as a full-speed hub.
http://www.ti.com/product/TUSB2046I

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Plug-in USB Sound Cards/Devices

Bus 001 Device 092: ID 1b3f:2008 Generalplus Technology Inc. -- 3
Bus 001 Device 091: ID 1b3f:2008 Generalplus Technology Inc. BRCM20702 Hub -- 4
Bus 001 Device 089: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller -- 2
Bus 001 Device 088: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter -- 1
Bus 001 Device 013: ID 046d:0a03 Logitech, Inc. Logitech USB Microphone

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How to Switch Audio Device on the Fly

pactl load-module module-alsa-sink device=Headset; sleep 2
pactl load-module module-alsa-source device=Headset; sleep 2
echo "set-default-sink alsa_output.Headset" | pacmd
echo "set-default-source alsa_input.Headset" | pacmd

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Audacity

apt install audacity:

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Alpha Audio

https://www.audiopluginsforfree.com/free-alpha/

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lv2

LV2, an acronym for LADSPA Version 2, is a set of royalty-free open standards[1] for plug-ins and matching host applications. It includes support for the synthesis and processing of digital audio and CV, events such as MIDI and OSC, and provides a free alternative to audio plug-in standards such as Virtual Studio Technology (VST) and Audio Units (AU).
https://en.wikipedia.org/wiki/LV2

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Cleanfeed

Cleanfeed is multitrack, multi-party live audio and recording using only a browser.
https://cleanfeed.net/

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Dummy Output and system is not playing audio

see: https://support.system76.com/articles/audio/

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References

Independent ALSA and linux audio support site - MultipleCards:
https://alsa.opensrc.org/MultipleCards

How to use Pulse to manage sound on Linux::
https://opensource.com/article/17/1/linux-plays-sound

Understanding Linux Audio:
http://slackermedia.info/handbook/doku.php?id=linuxaudio

PulseAudio/Troubleshooting:
https://wiki.archlinux.org/index.php/PulseAudio/Troubleshooting#Muted_audio_device

Configuring Sound on Linux/HW Address: https://en.wikibooks.org/wiki/Configuring_Sound_on_Linux/HW_Address

How do you set a default audio output device in Ubuntu 18.04?:
https://askubuntu.com/questions/1038490/how-do-you-set-a-default-audio-output-device-in-ubuntu-18-04

How do you switch the audio out from the speakers to a USB speaker from the command line?:
https://askubuntu.com/questions/61798/how-do-you-switch-the-audio-out-from-the-speakers-to-a-usb-speaker-from-the-comm

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Glenn Lyons VK4PK
glenn@LyonsComputer.com.au
Ver:gnl20200130 - pre published v0.9