AC3 - SPDIF Passthrough - Pulseaudio - Karmic 9.10

[sammydee]

Try running your media player like this:

pasuspender $MEDIA_PLAYER_APP

This will suspend pulseaudio while the app is running and allow it full control of the sound card.

[lloydsmart]

Thanks for the tip , sammydee, but unfortunately this didn't work too well for me.

My media player app is XBMC (SVN version), and using this option just caused it to crash (freeze) when I select any video to play, bitstream or not.

Maybe I should compile a version of XBMC with pulseaudio support disabled? Or are there any other steps I should be taking to make ALSA available to the app?

Once again thanks for your help.

EDIT: Also, is there any chance we could get the "Solved" tag removed from this thread? We might get more responses that way. Thanks.

[markbuntu]

This has been discussed on the pulseaudio mailing list

On Mon, 05.10.09 14:30, Dave Moore (davewantsmoore@gmail.com) wrote:
>
> > Hi Everyone. I'm really sorry if this has been covered before, I've read
> > back through the past 6 months list history and found nothing.... and my
> OS
> > (ubuntu) and application support forums/lists are not being very helpful.
> >
> > I would like to pass digital audio completely unaltered ("bit-stream") to
> my
> > SPDIF output - Can this be done with pulseaudio?
>
> No. Not at this time. (See other mails in this thread for what is planned)
>
> If you need ac3 pass-thru then you need to bypass PA. Just make sure
> you are not using the SPDIF port for PA (use g-v-c or pavucontrol and
> make sure the sound card is notconfigured for any of the 'digital
> iec985' modes).
>
> Lennart

Message: 4
Date: Tue, 6 Oct 2009 11:56:14 -0700

You could use the device reservation utilities for this. When you have
encoded data for pass through you can PA to let go off the device. See
code in module-reserve
- P

So, there is some hint how to do it. Maybe someone could figure out this module-reserve and get back with a solution. I don't use AC-3 passthough so I cannot do it myself.

[Wyv]

Try running your media player like this:

pasuspender $MEDIA_PLAYER_APP

This will suspend pulseaudio while the app is running and allow it full control of the sound card.

This works for me, thanks. Still a workaround but it is simpler than my GUI method.

[tvcasualty]

Can anyone help me out on giving pulse the boot and seting ALSA back up on 9.10?

This is a huge issue for me, and is the first time I've been let down in any way from a new Ubuntu release. Frankly, I'm not sure how they let this slide through. Happy to fix on my own, but last time I tried I had to reformat. Next try will have me put 9.04 back on...

[whittaker007]

I can't tell you exactly all the steps I have been through to get to where I am since this issue has caused me to try a lot of things that have not worked. However what I have done is install a few ALSA packages into Karmic, so I have both ALSA and Pulse at the same time. Using the Pulse volume controls I set Pulse to output to normal stereo out (so not using iec985). Even though Pulse is set to output to normal stereo, I still hear the standard system audio in stereo through the optical out.

From there I got AC3 passthrough working in both XBMC and VLC by assigning them each to use the iec985 output. This works pretty well but it's not perfect. Here are the issues I still have:

• System sound is muted and volume set to zero every time I restart. This is a real pain since I have to use the gui to set the volume which is a big usability problem for an HTPC and I'm a long way off getting this thing to work with a remote. Setting the volume, storing the preferences and restoring them as a startup item has not worked.
• Occasional audio dropouts: sometimes I lose stereo sound but can still get passthrough. Sometimes it's the other way around. Sometimes it's both. The only cure is a restart.
• I can only get VNC to give me a remote desktop style duplication of the currently logged in user - the same screen I see on my TV. Whenever I try to set it up to start a new user session on a virtual display I can't start gnome, get a login window or anything - just an empty black & white X window. OK this has nothing to do with sound but it's driving me nuts!

[adix87]

I had this problem. Here is what i did.
First, sorry for my bad english.

The problem was that i did not get surround sound from my Toslink optical cable. Only stereo. My soundcard is Xplosion 7.1 something..
Well first i didn't get sound at all but then i enabled IEC958 output from ALSA mixer that i installed from ubuntu software center.
Now i hear stereo sound.

Now for 5.1 passthrough.
Before you remove anything and mess up everything try this. Launch VLC, go to options -> Audio. Enable"Use S/PDIF when available" AND select Output device. "Default" is NOT okay here. You need to choose ALSA audio output. Default is something else i don't know. This will probably work for other players if they let you choose the output. But for example the normal "movie player" doesn't work with DTS or DD for me.
This is how i got it working.. other stuff i did was:
I removed the pulseaudio stuff from my system by launching "Ubuntu Software Center" and searched for pulseaudio and removed all packages i saw.
This step might not be necessary.
And in GNOME ALSA Mixer i have enabled IEC958 5V, IEC958 Copyright and IEC958 Output.
And if you go to System -> Pref -> Sound -> Hardware tab . It is okay that it says "Digital output Stereo". VLC will still play in 5.1 DTS or DD because its passtrough, and youtube clips will play in stereo but also through optical cable.

If this didn't work, reeboot and try in VLC again.


I hope i helped atleast someone.

[whittaker007]

I managed to get it working without removing Pulse. Here is what I did:

1. Install the Alsa libraries
2. Open the Pulse default Sound Preferences
3. Click the Hardware tab
4. Choose Analog Stereo Duplex profile
5. In every application that supports hardware configuration, set sound output to IEC985 or similar

Of course your hardware may differ. The surprising thing for me is that if I select any other non-digital profile other than Analog Stereo Duplex it doesn't work. But I now have automatic 5.1 and stereo out working in VLC and XBMC. I haven't spent enough time with MythTV to get that working yet, and I only get stereo from the other media players, but VLC, XBMC and MythTV are the only ones I care about.

My system volume seems to be stable now and not muting on restart, however I also recently switched to Linux Mint (built on Karmic) so I don't know whether that made a difference in that case. I also fixed my VNC problem, though that's OT.

[LucidParody]

Whittaker, what are the alsa libraries?

[whittaker007]

Whittaker, what are the alsa libraries?

Open a terminal window and type:

sudo apt-get install alsa