GTS450 - only stereo HDMI audio in Mint 10

[moltek]

Hello,

I am trying to setup my Linux Mint 10 based new HTPC. The only issue I have left is lack of multichannel audio via HDMI connection. My GTS450 HDMI output is connected to Denon 1911 receiver and then to TV. Originally I had no sound at all but after upgrade to newest NVidia driver (currently 270.26) and kernel (2.6.38rc4) and ALSA (1.0.24) I enjoyed stereo sound.

I had noticed today the update to the GPU HDMI Audio document: ftp://download.nvidia.com/XFree86/gp...dmi-audio.html and installed 2.6.38rc6 kernel.

I installed the kernel first then reinstalled NVidia drivers (X would not start otherwise). After this when I used sount-test with -c8 option I was able to hear all 8 channels but only through front speakers.
Next thing I did was to reinstall ALSA 1.0.24 as I noticed that after kernel upgrade ALSA went back to 1.0.23. This however restored the previous result from sound-test -c8: I am only able to hear sound for front speakers.

I have posted this on ubuntuforums.org too, but got no help there.

- PulseAudio detects HDMI as Digital Stereo only.
- Switching on and off on-board audio changes nothing.
- probe_mask works (leaving only one device available) but it only removes unnecessary devices not influencing numbers of useful channels
- ELD data seems to be correct and in dmesg I can see 10 speakers reckognised

Any ideas?

[cehoyos]

Originally Posted by moltek

- probe_mask works (leaving only one device available) but it only removes unnecessary devices not influencing numbers of useful channels

Did you remove probe_mask and run speaker-test (with four different devices) as explained in the "HDMI Audio" document?

Carl Eugen

[moltek]

Originally Posted by cehoyos

Did you remove probe_mask and run speaker-test (with four different devices) as explained in the "HDMI Audio" document?

Yes, I tried this too. Only one of the devices (the one selected by probe_mask) produces sound in stereo. Others are completely quiet (they are not muted in alsamixer).

[moltek]

I have recompiled ALSA 1.0.24 from sources but this time I applied to ALSA sources patch to multichannel issue mentioned in "NVidia HDMI Audio" document.
This made the trick!!!!

Well, the multichannel issue above was patched in kernel but still the same modules are part of ALSA (patch_hdmi.c file). Does this mean ALSA is a part of kernel?? (seems I need to learn more )

Using speaker-test for 8 channels I can hear all of them. It is not as it should be though: I have LFE working, but all left channels are audible in FL, all right channels - in FR. Centre channel is reproduced in both FL and FR. They are all mixed together into 2.1.
My receiver however recognizes the signal as 7.1 multichannel (for the first time). Pulseaudio still displays my hardware as "HDA NVidia Digital Stereo (HDMI)".
I am also able now to bitstream DTS and DTS-EX to the receiver (but not DTS HDMA). Dolby does not work (AC3, TrueHD). I am not sure though if I have proper samples for these HD formats.

Any ideas how to solve channel mixing issue?

EDIT: pulseaudio does not seem to be an issue as turning it off changes nothing

[moltek]

Having no luck with Mint, I decided to start from fresh Maverick install (using USB disk). Here are the steps
- install Ubuntu 10.10 Desktop x86
- no sound, audio does not work (aplay -l does not show any NVidia devices),
- install 270.39 NVidia driver from ppa:ubuntu-x-swat/x-updates
- still no sound, aplay -l does not show any audio devices (my onboard audio is switched off),
- install alsa update from ppa:ubuntu-audio-dev/ppa
- aplay -l shows HDA Nvidia, sound is played by sound-test (but only 2 channels, rest of them are not audible).

ELD data is correct, showing possible 8 channels and all multichannel codecs.

Again, any comments on how to solve this? Should I simply wait for Natty and hope for the best?

[moltek]

Final update: issue fixed.

The issue was caused by a HDMI cable (as surprising as it may sound). It was quite cheap HDMI 1.4 cable.

Now I have full 7.1 sound and passthrough for all formats (including HD codecs using Anssi's ffmpeg patch).