how to understand list of soundcards; meaning of MID, HDMI, PCH

Question

Command aplay -l produces a list of "all soundcards and digital audio devices".

On my brand-new Fujitsu Esprimo desktop, I get:

**** List of PLAYBACK Hardware Devices ****
card 0: MID [HDA Intel MID], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: MID [HDA Intel MID], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: MID [HDA Intel MID], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 0: ALC671 Analog [ALC671 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

lspci -v command shows two audio devices:

00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06)
    Subsystem: Fujitsu Technology Solutions Device 11e7
    Flags: bus master, fast devsel, latency 0, IRQ 48
    Memory at f7c34000 (64-bit, non-prefetchable) [size=16K]
    Capabilities: <access denied>
    Kernel driver in use: snd_hda_intel

00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 04)
    Subsystem: Fujitsu Technology Solutions Device 11eb
    Flags: bus master, fast devsel, latency 0, IRQ 47
    Memory at f7c30000 (64-bit, non-prefetchable) [size=16K]
    Capabilities: <access denied>
    Kernel driver in use: snd_hda_intel

Now my questions:

How it comes my office computer has two sound cards? These are both standard on-board cards, right?

What's the meaning of MID, PCH, HDMI?

Which one is connected to the moss-green standard plug?

It's a Fujitsu Esprimo Desktop. – Joachim W Apr 03 '14 at 20:58 — Joachim W, Apr 03 '14 at 20:58
I edited the question to provide the output of lspci -v. – Joachim W Apr 03 '14 at 21:06 — Joachim W, Apr 03 '14 at 21:06

Warren Young · Accepted Answer · 2014-04-03T21:24:50.157

What's the meaning of MID, PCH, HDMI?

MID is a compound acronym with an unenlightening expansion: it is the Message Signalled Interrupt Capability ID register in the C220 series chipset your machine uses.

(How did they manage to boil that unwieldy term down to MID, you ask? MSI is a well-established acronym in its own right, so this is the "MSI ID" register, or MID. They could just as well have called it the MSIID, or MSICID, but I guess people like TLAs too much. See section 17.1.1.25 in the Intel 8/C220 series PCH datasheet.)

Anyway, MID isn't important here. What matters is that it's tied to the HDMI outputs, which is the true audio output device, from the user's perspective.

HDMI is a digital audio/video transport, most often seen on consumer entertainment equipment like Blu-ray players, but also on some PCs, especially the sort designed to be used as home theater PCs. Since HDMI can carry sound as well as video, it shows up in your list of sound output devices. Some people do use it as a dedicated sound output, sending HDMI to a DAC while video goes out another path, such as VGA.

I don't know why you see three HDMI output paths, but it is almost certainly not because your computer has 3 HDMI output connectors, or even the capability of such. I hesitate to even guess what the distinction among them is, though if you post your lspci -v output, I could research the ICs involved and would probably figure it out.

PCH is what you'd call your actual "sound card," though it isn't actually a card in the machine. PCH is Intel's name for a family of ICs that include sound output. Because there have been many generations of PCH, you often see it followed by a fragment of the IC part number, like PCH C220, which helps you decide whether a given driver is compatible with the particular PCH family variant on your motherboard.

Which one is connected to the moss-green standard plug?

PCH.

score 1 · Answer 2 · answered Apr 03 '14 at 16:49

Not sure what MID and PCH stand for, so I can't answer that part. HDMI is High-Definition Multimedia Interface. HDMI can carry audio, and it'd appear your machine has (or could have) 3 HDMI ports.

The moss-green plug is the analog audio, the last one listed.

score 1 · Answer 3 · answered Apr 03 '14 at 21:16

According to a topic on the gentoo.org forums, "The MID card doesn't work at all (alsamixer says: "This sound device does not have any controls."). So it's useless, yet it is made the default card for some reason. "

The fix for it, as referenced on this post in the topic, is to add the following to the kernel commandline in your bootloader config: snd_hda_intel.index=1

This will set the default device to the PCH one instead of the MID one, which is your green plug. This may help you if you run into issues with the "default" sound device not working as expected.

how to understand list of soundcards; meaning of MID, HDMI, PCH

3 Answers3