ALSA or PulseAudio - what am I using right now?

Hi forum,

the actual problem is that my front (and only) speakers are reversed. Left sound comes from the right and vice versa. That started with the update from Mint 17 to 19.2.

Now to find where to switch those channels, do I have to look into PulseAudio or ALSA?

pulseaudio 1:11.1-1ubuntu7.2 is installed as is
alsa-base 1.0.25+dfsg-0ubuntu5 and
alsa-utils 1.1.3-1ubuntu1.

$ inxi -Fxz
System:    Host: john Kernel: 4.15.0-55-generic x86_64 bits: 64 compiler: gcc v: 7.4.0 Desktop: MATE 1.22.0 
           Distro: Linux Mint 19.2 Tina base: Ubuntu 18.04 bionic 
Machine:   Type: Desktop System: Gigabyte product: N/A v: N/A serial: <filter> 
           Mobo: Gigabyte model: Z77X-UD4H serial: <filter> BIOS: American Megatrends v: F1 date: 11/02/2012 
CPU:       Topology: Quad Core model: Intel Core i7-3770K bits: 64 type: MT MCP arch: Ivy Bridge rev: 9 L2 cache: 8192 KiB 
           flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 56058 
           Speed: 2061 MHz min/max: 1600/3900 MHz Core speeds (MHz): 1: 1879 2: 1907 3: 1903 4: 1744 5: 1882 6: 1904 7: 1633 
           8: 1904 
Graphics:  Device-1: Intel Xeon E3-1200 v2/3rd Gen Core processor Graphics vendor: Gigabyte driver: i915 v: kernel 
           bus ID: 00:02.0 
           Display: x11 server: X.Org 1.19.6 driver: modesetting unloaded: fbdev,vesa resolution: 1680x1050~60Hz 
           OpenGL: renderer: Mesa DRI Intel Ivybridge Desktop v: 4.2 Mesa 19.0.2 direct render: Yes 
Audio:     Device-1: Creative Labs EMU10k1 [Sound Blaster Live! Series] driver: snd_emu10k1 v: kernel bus ID: 05:00.0 
           Sound Server: ALSA v: k4.15.0-55-generic 
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Gigabyte driver: r8169 v: 2.3LK-NAPI 
           port: c000 bus ID: 06:00.0 
           IF: enp6s0 state: up speed: 100 Mbps duplex: full mac: <filter> 
Drives:    Local Storage: total: 720.54 GiB used: 178.51 GiB (24.8%) 
           ID-1: /dev/sda vendor: ExcelStor model: J9250 size: 232.89 GiB 
           ID-2: /dev/sdb vendor: Samsung model: HD403LJ size: 372.61 GiB 
           ID-3: /dev/sdc vendor: Hitachi model: HDS722512VLSA80 size: 115.04 GiB 
Partition: ID-1: / size: 47.81 GiB used: 8.81 GiB (18.4%) fs: ext4 dev: /dev/sdc1 
           ID-2: /boot size: 447.0 MiB used: 352.0 MiB (78.7%) fs: ext2 dev: /dev/sdb1 
           ID-3: /opt size: 57.78 GiB used: 35.00 GiB (60.6%) fs: ext4 dev: /dev/sdb9 
           ID-4: swap-1 size: 15.62 GiB used: 0 KiB (0.0%) fs: swap dev: /dev/sdb6 
Sensors:   System Temperatures: cpu: 29.8 C mobo: 27.8 C 
           Fan Speeds (RPM): N/A 
Info:      Processes: 225 Uptime: 6h 18m Memory: 14.63 GiB used: 2.01 GiB (13.8%) Init: systemd runlevel: 5 Compilers: 
           gcc: 7.4.0 Shell: bash v: 4.4.20 inxi: 3.0.32

Why does inxi identify ALSA as sound server while PulseAudio is installed?

https://www.linuxquestions.org/quest...annels-476400/ mentiones /etc/asound.conf, which doesn't exist on my system. But /etc/pulse/deamon.conf does (and the fix mentioned in the link doesn't work).

So, go for ALSA or Pulse to fix the reverse-channel-problem?

Swap them in Alsa. Alsa does the grunt work. Pulse is a front end.

I created a file /etc/asound.conf with this in it:

pcm.swappedw {
    type route
    slave.pcm "hw:0"
    ttable.0.1 1
    ttable.1.0 1
}

ctl.swappedw {
    type hw
    card 0
}

Then indeed, qmmp's alsa output plugin dialog presented a new device "swappedw".
The final "w" is a sign for me that changes in /etc/asound.conf have indeed been noticed by the rest of the system. Every time I change something there, I change that letter, too. And through various attempts, I saw it get "x", "y", "z" and as you see now "w".

But, qmmp's balance slider behaves the same every time. Slide it to the left and sound goes to the right.

I have seen variants of above syntax with a c-like ";" at every line end. But that also didn't work for me. Is ";" just a marker for comments here?

Ok, I would like to swap the channels in ALSA, but I don't know how. Any hints?

Ok, I would like to swap the channels in ALSA, but I don't know how. Any hints?

I did the briefest of searches and came up with a way of doing it in pulse

Originally Posted by business_kid I did the briefest of searches and came up with a way of doing it in pulse

Indeed...