Unable to get 5.1 over intel HDMI correctly
I'm writing because I've a problem that I'm unable to solve; I've try everything I've found with no result
I have a PC with an Intel Haswell processor that is connected via HDMI to an AV, and from the AV to the TV. In Windows 7 i have sound over HDMI in 5.1 perfectly but linux is another story (kubuntu 13.10), so it's a configuration problem.
There is no problem with sound throught HDMI in stereo, but when I select 5.1 it's not ok. When 5.1 in some of the speakers (the most of them) sound is outputted over the speaker it's supposed to, but over another speaker too, with a distorsion and noise (like scratches).
I mean, front left sound ok, but rear left sounds via itself but via font left too, and right ones sounds via front and rear.
In audio preferences I have two HDMI stereo and two HDMI surround, ¿why? I think it could be part of the problem:
I didn't pay attention to this when I used stereo since works ok, but now that I need 5.1 it makes me think that it's not ok.
In pulseaudio I've the same think, but each one appears three times:
The first thing I tried is edit /etc/pulse/daemon.con file and add lines:
default-sample-channels = 6
enable-lfe-remixing = yes
I also tryed to edit /etc/modprobe.d/alsa-base.conf and add:
options snd-hda-intel model=3stack-6ch-dig
But problem reamains
Then I installed PulseAudio Manager to check all volumen on it was at 100% and not below, but nothing...
In alsamixer there is no much to do, it appears on the sound card:
From the two HDMI 5.1 that appears on audio preferences, the working one (bad working) matches with left one in alsamixer (named SPDIF2), I know it becouse when I mute it with "M" key sound mutes, when muting the other ones in alsamixer nothing happends.
I've been handling volumes of each speaker in pulseadio and it seems that 6 channels are correctely recognized, but some of the channels transmit sound via more than one speaker. When I silent for example all speakers but front right, i get sound only when I try this front left on audio preferences, but rear front also sounds, and I have noise and scratches.
I've been reading something about mapping channels and editing He estado ley /etc/asound.conf file. My system had not this file, I created it and include a code that is supposed to solve the problem, but problem remains exactly the same. Perhaps I need the content of asound.conf for just this model of sound card (the one on Intel HD Haswell).
To sum up, I can't get sound over 5.1 correctly and I don't know what to do, so I really thank any help.
Thanks in advance.
What exactly are you trying to do?
Do you just want movies to be in 5.1? I usually have HDMI stereo selected and the DTS or DD signal from a movie is still send to my AV so you get 5.1 there. For everything else you get stereo which usually is enough (post-proessing is done on the AV, such as 4channel stereo and others).
Thanks for the answer, droste,
Originally Posted by droste
Yes, it's for using the computer as HTPC.
I've not try what you say, but I suppose that if I've to decode the sound in the computer I'll have the problem of being limited to stereo, and since with windows 7 there is no problem at all (5.1 works ok in the windows test) I see it's a software problem, so I would like to solve it.
Yes you would be limited to stereo for pre-decoded surround sound. But does this actually happen?
It's most probably a bug in the ALSA driver, because 5.1 over HDMI is a pretty recent change I wasn't even aware of until I read your post.
Best idea would be to file a bug against the ALSA driver (snd_hda_intel IIRC).
You need to make sure that the application is set up to pass through the 5.1 signal without decoding to PCM. If you are using PulseAudio, this is only supported in very recent versions.