How to check why sound over HDMI doesn't work

Question

I installed Gentoo clean on my system, except my /home but I deleted all hidden folders that might have an impact on sound (.mplayer .pulse* .config .esd_auth and more) and with a fresh user adduser mistertest -m -G audio,video,users the result is the same, no sound when I play a file in mplayer.

Its a Z68 Chipset and I am using the Intel IGP H2000 inside my CPU, so this should not be an issue of the spdif connector on my mainboard and I think i have installed all the correct modules in the kernel. I have no aditional hardware to check if my sound is working at all (no headset or external speakers), but I suppose the problem is either some bad config or the internal spdif (if there is such).

dronemother ~ # lsmod | grep snd
snd_hda_codec_hdmi     22705  1
snd_hda_codec_realtek   190506  1
snd_hda_intel          21727  3
snd_hda_codec          63422  3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel
snd_hwdep               5726  1 snd_hda_codec
snd_pcm                69969  3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec
snd_timer              17697  1 snd_pcm
snd                    53814  13 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_    timer
soundcore               5009  1 snd
snd_page_alloc          6641  2 snd_hda_intel,snd_pcm

dronemother ~ # lspci -v
# cut other stuff away here    
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05)
        Subsystem: ASRock Incorporation Device 1892
        Flags: bus master, fast devsel, latency 0, IRQ 46
        Memory at fe600000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: [50] Power Management version 2
        Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+
        Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
        Capabilities: [100] Virtual Channel
        Capabilities: [130] Root Complex Link
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd-hda-intel

I have pulseaudio, alsa-plugins, mplayer, mixer and pavucontrol installed. I get no errors when playing a file in mplayer just no sound.

So how can I examine where exactly my problem is located?

Edit: I just booted the PC from a Ubuntu Live USB stick, sound did not work, too. (took a bit longer, cannot restart the server every day, some people rely on its services.)

Answer 1

After asking this questions multiple times on gentoo IRC and finally the forums, I was pushed in the right direction and able to solve the problem.

~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC892 Analog [ALC892 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 1: ALC892 Digital [ALC892 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

As stated in line2 these are all the available playback devices. I configured my /etc/asound.conf accordingly. (can be done in ~/.asoundrc per user, too)

~ $ cat /etc/asound.conf
pcm.analog {
        type hw
        card 0
        device 0 }

pcm.digital {
        type hw
        card 0
        device 1 }

pcm.hdmi0 {
        type hw
        card 0
        device 3 }

pcm.hdmi1 {
        type hw
        card 0
        device 7 }

In each entry the part after the dot is a local alias free to chose. Other applications can use this to identify the device. Using aplay -D plug:hdmi1 ~/soundfile.wav finally played a sound (actually you should play a wav file cause aplay cannot decode mp3 or likewise).

So I appended these few lines to my /etc/asound.conf

pcm.!default {
        type  plug
        slave.pcm "hdmi1"
}

And now everything works like a charm.