[chris2922]

I've had a good read on this subject here and on the and the HTPC section of the 'avforums' but cannot find a solution for my sound problem (or definative response that it not possible).

I have my Zotac ION-ITX-A connected to an Onkyo 605 amp via HDMI.

I have a 16gb USB flash drive with 9.04.1 installed and have updated the nvidia drives with the newer version - restrictedDrivers.NVIDIA.185_18_14.zip - by dropping them onto the USB using a windows pc. They work fine for movie playback with VDPAU enabled.

My problem is with the sound outputted via HDMI. My amp shows this as PCM regardless of the sound stream the movie contains. I have a copy of Wolverine with AAC 5.1 sound. I can confirm this by pressing 'o' during playback. This comes through on the amp display as PCM.

To try and get the HDMI connection to pass DTS/DD(AAC) to my amp i selected the following settings in 'audio hardware' under 'system':

Audio ouptut device: Digital
Dolby Digital (AAC) capable: Yes
DTS capacble: Yes
Audio Output device: hdmi (lowercase)
Passthrough Output device: hdmi (lowercase)
Downmix Multichannel to Stereo: No

I have also tried using a co-ax lead instead of traferring the sound via hdmi. In this case i got Navigation sounds (which HDMI does not provide on my system oddly) but the problem with PCM sound is still the same. With a co-ax lead my settings are:

Audio Output device: iec958 (lowercase)
Passthrough Output device: iec958 (lowercase)

This was just for testing though - i need to use the HDMI lead for my sound if my system is to work correctly. (I feed the HDMI sound from XBMC back up to my tv (for late night viewing when i cant have my speakers on) and this is not possible with a co-ax connection - only HDMI.)

Im not sure what to do now to proceed. I have bought this to replace my xbox 360 which i was using to stream video. It only supported 2 channel stereo in MP4 files so i was having to re-code 5.1 channel audio to 2 channel on my pc first. I wanted to use full surround sound so bought this hardware, but now im stuck with stereo on my new system as well!

Hope someone can help me sort this. Otherwise ive gained some (admittedly very) nice menus and no improved sound support!

[topfs2]

Could you pastebin your Debug Log. And your alsa version would also be interesting you can do

Code:

cat /proc/asound/version

in the terminal to obtain the version

[chris2922]

Thanks for your assistance. Do you want me to enable debug logging before pasting my Debug Log to one of the pasting websites?


My alsa version is 1.0.18rc3.

Now you have highlighted it, i have done a search and found the current version is 1.0.21a.

I have so far been unable to find out how to upgrade to it though. Being a windows user i keep thinking i need to find a file to download and copy over to my thumb drive. It is the method i used to update my nvidia drivers. In linux its all about command prompt lines though isn't it.

Can you help me out with the syntax please? I've had a search around and keep finding different suggestions. I dont want to make matters worse by implementing something incorrectly.

Also, i cannot enter Terminal from XBMC Live as it requires 3 keys to be pressed - and my ps2 keyboard wont allow it. Im using Putty on my Windows PC to SSH into the Linux session to run terminal - in case that makes a difference.

[chris2922]

I have found the following guide for upgrading alsa. Im using Putty on a Windows PC to access Ubuntu.

Can someone familiar with process please have a read through and check this is safe to perform on my XBMC Live usb flash drive install. Is there a way of rolling back the settings if this goes wrong?

Will this reset my ALSA settings and potentially make things worse?

(i'd substitute the entries with the lastest 21 or 21a versions where appropriate)

http://webupd8.blogspot.com/2009/08/how-...buntu.html

[chris2922]

Well, i followed the guide i posted above through 'putty' and it went fine - im now on ALSA version 1.0.21(a).

Running 'alsoconf' went fine and detected my nvidia hdmi chipset, and running 'alsamixer' i checked everything was turned up full - which it was.

Sadly, this has made no difference to my situation.

Im still outputting PCM Stereo to my Onkyo 605 via hdmi when the source file has AAC 5.1 sound. Can someone pleeease help me out!

I can post a debug log if it will help but i need to know what actions to perform once im logging to make it useful.

[chris2922]

Does anyone have the Zotac IONITX-A Motherboard outputting bitstream 5.1 sound via HDMI under XBMC Live or XBMC over Ubuntu?

I havent given up with this yet, but if its not possible and im wasting my time id like to know now.

[HitchHiker]

I will go home and test it tonight.

[HitchHiker]

I checked it with a fresh install of 9.04.1 Live, to a 4gb SD card. I was able to get both DTS and DD via HDMI. I didn't update any drivers or make any changes to the install other than to setup the audio, the same as your first post. My receiver is a Sony STR-DG850. I don't know if that has anything to do with it or not.

[chris2922]

Thank you for taking the time to test that for me.

I suppose the only element that differs between our setup's are the amps.

I have no idea why mine is not working. If i switch the just the Onkyo on and leave it standing, the display on the dvd input reads: PCM HDMI DSP.

If i then turn the Zotac on the display flashes for a second (while it reads the Zotac output i guess) then reverts back to the above.

I would expect when a movie with a AAC 5.1 soundtrack was played the Onkyo would recognise this and change to DD. It does not.

It does take both DD and DTS quite happily from my Pioneer dvd player and Xbox 360 though. I have no idea what to do next!

[chris2922]

Followed instructions for putting up Debug Log. If anyone can help from this information please do:

http://pastebin.com/m5b622aaf

[ubiq]

Im still outputting PCM Stereo to my Onkyo 605 via hdmi when the source file has AAC 5.1 sound.

I would expect when a movie with a AAC 5.1 soundtrack was played the Onkyo would recognise this and change to DD. It does not.

AAC is not DD. Unless XBMC is capable to encode AAC track on-the-fly to DD you are not supposed to see your receiver to detect the audio stream as DD. What you would like to have is XBMC sending AAC 5.1 track as multichannel PCM over HDMI to your receiver. If the audio system is unable to send multichannel PCM to your receiver it falls back to sending 2 channel PCM (that it supports) for you AAC 5.1 track.

There are also some receivers out there that directly support AAC tracks. Unfortunately even if XBMC would passthrough AAC track over HDMI to your receiver, Onkyo 605 does not support that.

I would also like to know if current alsa version is able to send 7.1 LPCM over HDMI with modern NVidia chipsets so I can start looking for a new receiver and get more then just 2 channel PCM from my FLAC tracks.

[chris2922]

Thanks ubiq - i was wasting my time afterall!

Right; so AAC is not dolby digital. Great - and thats what all my HD MKV files have as audio tracks!

I've read up a bit and it seems the best option for me is to convert the AAC audio to AC3.

If i do this, will i keep the digital surround track, and will XBMC output a signal to my amp that it will interpret as DD?

[ubiq]

I've read up a bit and it seems the best option for me is to convert the AAC audio to AC3.

If i do this, will i keep the digital surround track, and will XBMC output a signal to my amp that it will interpret as DD?

If you convert your AAC track to DD (same as AC3) it will suffer from lossy to lossy conversion and sound quality will not be optimal. If you mux transcoded DD track back to your mkv XBMC will play that track like any other DD track and your receiver will detect it as DD track.

The best way for you is to configure your HTPC to output AAC tracks as multichannel PCM to your receiver. This way you will get the best possible audio quality from your audio tracks and you don't need to transcode AAC tracks and mux them back for all your movies. You should read this thread to help you configure your alsa.

[chris2922]

I've read through that post twice now and im no nearer understanding it all. There's no way im hacking my alsa install like that, i barely understaood the process i followed to update it to .21.

I suppose ill just have to live with AAC audio playing as stereo. I waited years for a suitable small, cost effective htpc platform to come along and i thought the zotac board fitted the bill. Why theres always *something* that doesnt work is beyond me. Just build a board that works for christ's sake.

If so many av amps cannot decode AAC audio why the hell are so many people insisting to encode audio in AAC? What's wrong with AC3?

Im really pi&*ed off with the whole thing. Unless NVidia/ALSA release drivers that make this dodgy hack job official, im staying well away.