Audio Self-Reconfiguring to HDMI under 18.3 Sarah

[ytene]

Hello Everyone...

Bit of a "good one" as issues goes, I think...

I have just upgraded a small fanless system of mine from Mint 17.3 to Mint 18.3 [both are 64-bit, Cinnamon-based versions]. I use the term "upgraded" when in fact I should write "performed a clean installation on a brand new SSD" and I'm now experiencing a weird problem with my audio configuration. I had seen this with earlier editions of the 18.x range - which had in fact prompted me to remain with 17.3 for as long as I have.

The issue I experience is that, quite frequently, my system will dynamically, unilaterally and without advising me switch from my chosen audio configuration to a different, incorrect one, leaving me with no sound.

Here are some basic system details, then I'll cover what I see and what I've done to explore the issue. I would be very grateful for any advice anyone can offer that would allow me to "set and forget" my audio configuration...

Asus H170i Pro Gaming Motherboard
Intel Core i7 7700T CPU
32Gb RAM
1Tb Samsung 850 Pro SSD


$ inxi -Fxz
System: Host: KabyLake Kernel: 4.10.0-42-generic x86_64 (64 bit gcc: 5.4.0)
Desktop: Cinnamon 3.6.7 (Gtk 3.18.9-1ubuntu3.3) Distro: Linux Mint 18.3 Sylvia
Machine: Mobo: ASUSTeK model: H170I-PRO v: Rev X.0x Bios: American Megatrends v: 3401 date: 03/16/2017
CPU: Quad core Intel Core i7-7700T (-HT-MCP-) cache: 8192 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 23232
clock speeds: max: 3800 MHz 1: 900 MHz 2: 899 MHz 3: 899 MHz 4: 899 MHz 5: 899 MHz 6: 899 MHz
7: 899 MHz 8: 900 MHz
Graphics: Card: Intel Device 5912 bus-ID: 00:02.0
Display Server: X.Org 1.18.4 drivers: intel (unloaded: fbdev,vesa)
Resolution: 1920x1200@59.95hz, 1920x1200@59.95hz, 1920x1200@59.95hz
GLX Renderer: Mesa DRI Intel Kabylake GT2 GLX Version: 3.0 Mesa 17.0.7 Direct Rendering: Yes
Audio: Card Intel Sunrise Point-H HD Audio driver: snd_hda_intel bus-ID: 00:1f.3
Sound: Advanced Linux Sound Architecture v: k4.10.0-42-generic
Network: Card-1: Intel Ethernet Connection (2) I219-V driver: e1000e v: 3.2.6-k bus-ID: 00:1f.6
IF: enp0s31f6 state: up speed: 1000 Mbps duplex: full mac: <filter>
Card-2: Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter driver: ath10k_pci bus-ID: 01:00.0
IF: wlp1s0 state: down mac: <filter>
Card-3: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
driver: r8169 v: 2.3LK-NAPI port: e000 bus-ID: 03:00.0
IF: enp3s0 state: down mac: <filter>
Drives: HDD Total Size: 1024.2GB (2.5% used) ID-1: /dev/sda model: Samsung_SSD_850 size: 1024.2GB
Partition: ID-1: / size: 16G used: 1.2G (8%) fs: ext4 dev: /dev/sda5
ID-2: /usr size: 16G used: 5.7G (40%) fs: ext4 dev: /dev/sda7
ID-3: /tmp size: 7.4G used: 18M (1%) fs: ext4 dev: /dev/sda10
ID-4: /var size: 16G used: 1.5G (11%) fs: ext4 dev: /dev/sda9
ID-5: /home size: 16G used: 403M (3%) fs: ext4 dev: /dev/sda8
ID-6: swap-1 size: 16.54GB used: 0.00GB (0%) fs: swap dev: /dev/sda6
RAID: No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors: System Temperatures: cpu: 29.8C mobo: 27.8C
Fan Speeds (in rpm): cpu: 0
Info: Processes: 278 Uptime: 1:30 Memory: 3561.1/32047.4MB Init: systemd runlevel: 5 Gcc sys: 5.4.0
Client: Shell (bash 4.3.481) inxi: 2.2.35

This is, however, wrong - with specific reference to the stated audio output. The H170i motherboard does in fact include the Realtek ALC887 7.1 Channel High Definition Audio Codec, which supports Jack Detection and re-tasking...

My audio output from this device is sent via the Toslink / S/PDIF Optical Audio connection on the back panel to a Logitech 5.1 Z906 5.1 Speaker system...

Using the Cinnamon Main Menu, I can select Preferences >> Sound to get the audio applet. In the "Output" Tab [the left-most out of the 4 tabs across the top of the window] I then see 2 listed devices:

HDMI / DisplayPort Built-in Audio
Digital Output (S/PDIF) Built-in Audio


I set the output here to use the S/PDIF connector and I get excellent quality audio playback. However, if I then leave my computer idle [and not using this audio channel] for the amount of time it takes to pop to the kitchen and make a cup of tea... by the time I return there is a > 50% chance that the system will have unilaterally reconfigured my audio device to use HDMI.

Having read around this topic, I understand that S/PDIF, because it is an older audio codec, is forced to apply some limited signal compression during transmission. Whilst it is expanded at the amplifier end of the link, this will necessarily induce a loss in fidelity. I assume but don't know that the fact that HDMI is a better audio medium [no compression] means that software would be configured to "prefer" HDMI over S/PDIF.

Even more curiously, I get exactly the same symptoms when running 18.3 on my "Gaming" rig, which is based on an MSI Big Bang Power II motherboard [awful name, awesome board] that comes fitted with a Creative Labs Titanium X-Fi sound card [with optical out] and an nVidia 1080GTX that has HDMI out.

In all cases, Mint 18.3 [in fact Mint 18.x] will unilaterally reconfigure my audio setup to use the HDMI channel instead of S/PDIF.

This is incredibly annoying - this is a user-selectable attribute and in my case none of my monitors have speakers.

Does anyone know if it might be possible for me to set my audio configuration to use S/PDIF and then lock the permissions on the config file so as to stop whatever keeps reconfiguring from doing so again?

Very many thanks in advance for any ideas on this one...

[ytene]

Sorry, I meant to include the following, too:-

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC887-VD Analog [ALC887-VD Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 1: ALC887-VD Digital [ALC887-VD Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
Subdevices: 1/1
Subdevice #0: subdevice #0

[ytene]

Interesting footnote...

Today I left my PC long enough for my Mint screen saver to activate, but left it with Rhythmbox playing music, which continued after the screen lock took place.

When I returned to my PC and unlocked it, the act of performing the unlock caused the audio to switch from Optical out to HDMI out. Literally with the unlock process.

Does this help anyone take an educated guess at why this might be happening?

Thanks...