In Oneiric, the output of 5.1 sound (not AC3 passthrough, but multi-channel PCM) via the HDMI connector of my onboard Intel graphics card is finally working. This is really great!
For this to work, I have configured Pulseaudio to use the "Digital Surround 5.1 (HDMI) Output". The HDMI output of my computer is connected to a 5.1 receiver.
However, there is one nuisance: Whenever I start playing sound on the computer (e.g., rhythmbox or VLC, both playing via PulseAudio), I hear no sound. On my receiver I have to re-select the input source for the computer, which seems to initiate a HDMI handshake (it lasts 3 seconds). Only after this I am able to hear sound.
If I press pause and continue in Rhythmbox, the sound continues fine. If I stop and restart Rhythmbox, I have to do the above procedure again. The same is true for VLC and probably for all other players.
While playing around, I have noticed that sound is also working after killing pulseaudio while playing something in Rhythmbox. When the connection to Pulseaudio is killed, Rhythmbox tries a fallback to ALSA. As the Pulseaudio daemon was immediately restarted, this will result in Rhythmbox being connected via the ALSA plugin (before the connection was direct). It seems that Pulseaudio is doing the necessary things here, because after this I do hear sound (as long as Rhythmbox runs). However, this trick does not work for other players like VLC which don't fall back to ALSA.
Note that while for me this is just a nuisance, it may be a real blocker for other users. As long as you don't try to fiddle with the receiver inputs while playing sound on the computer, you hear absolutely nothing via HDMI. This includes the sounds from the speaker test dialog of Pulseaudio. I guess a lot of users would give up and think that HDMI output is broken in Ubuntu.
ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: pulseaudio 1:1.0-0ubuntu3
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC892 Analog [ALC892 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: philipp 7706 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'PCH'/'HDA Intel PCH at 0xfe520000 irq 50'
Mixer name : 'Intel CougarPoint HDMI'
Components : 'HDA:10ec0892,80862002,00100302 HDA:80862805,80862805,00100000'
Controls : 31
Simple ctrls : 16
Date: Mon Oct 31 18:07:22 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110426)
ProcEnviron:
LANGUAGE=de:en
PATH=(custom, no user)
LANG=de_DE.UTF-8
LC_MESSAGES=de_DE.UTF-8
SHELL=/bin/bash
SourcePackage: pulseaudio
UpgradeStatus: Upgraded to oneiric on 2011-10-31 (0 days ago)
dmi.bios.date: 11/15/2010
dmi.bios.vendor: Intel Corp.
dmi.bios.version: BLH6710H.86A.0076.2010.1115.1959
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: DH67BL
dmi.board.vendor: Intel Corporation
dmi.board.version: AAG10189-205
dmi.chassis.type: 3
dmi.modalias: dmi:bvnIntelCorp.:bvrBLH6710H.86A.0076.2010.1115.1959:bd11/15/2010:svn:pn:pvr:rvnIntelCorporation:rnDH67BL:rvrAAG10189-205:cvn:ct3:cvr:
It also works if I switch the Pulseaudio output configuration to "Digital Stereo (HDMI) output" and back while the sound is playing. As soon as the first change is done, I hear sound (in stereo, of course) and after the second change I have nice 5.1 sound.
So Pulseaudio is clearly able to do everything necessary to have sound, it just needs to do it automatically when starting playback.