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PostPosted: Wed Mar 24, 2010 7:20 am 
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Joined: Sun Oct 30, 2005 7:07 pm
Posts: 72
Folks,

I just replaced my KM5.5 install with R6.02 on my dragon v1.0 system with Chaintech AV-710 sound card. With 5.5, I had digital audio pass-through working great with the spdif output, but after installing R6.02, it stopped working. I was not concerned at first, as this happened often with upgrades. To start, I copied over my asound.conf file I used with 5.5 and made sure that MythTv was configured correctly for digital passthrough in the General menu (Screen 3). I restarted the machine, but still no digital audio. I started to check the forums at this point. I found posts from others having trouble, but did not see any mention of the AV-710. Since this card is part of the KRP - KnoppMyth Reference Platform, I had thought it would always be supported.

Here is what I have read and tried with no success:

http://mysettopbox.tv/phpBB2/viewtopic. ... if+working

http://www.mythtv.org/wiki/AllensDigitalAudioHowto

I see that R6.02 has Alsa 1.0.18, which should support digital audio fine, according to Allen's guide. Also, using Allen's guide, I was able to use a WAV file to ensure that the hardware is still working (I can play the file using aplay successfully). I also checked that the IEC958 output was enabled using alsamixer. And I tried the different asound.conf settings... but still, there is no digital output when using MythTv or any of its plugins.

Can someone please tell me if they have an AV-710 and have digital audio working with R6.02? I have spend 4 days now debugging and trying out different things, and am about at wits end. Thanks for any help!

Trevor


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PostPosted: Wed Mar 24, 2010 8:07 am 
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Joined: Fri Jun 23, 2006 10:57 am
Posts: 106
I don't have any suggestions for you but just wanted to say that pretty much out of the blue my digital audio broke recently. It was the oddest thing. Worked one day and then not the next. The last software update I had done was a week earlier.

It's not a system problem as mplayer works fine. Between this issue and random recording failures I have become quite frustrated with mythtv. I've run mythtv for a long time and debugging these things always reminds me that I'm not a C++ programmer :?

So I've done the unthinkable (no not Windows Media Center - not THAT unthinkable), I have begun a project to replace mythtv functionality. My own code so when it's broken I can fix it. Yeah it's a lot of work. Perhaps some day I will release it to the world when it's ready.

As for the audio issue I really haven't taken the time to even check the logs. I just no longer run mythtv where I need the digital audio. No audio issues using analog sound at other TVs in the house.

So like I said I don't have any solutions for you but I'll watch this thread in case someone comes up with something.


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PostPosted: Wed Mar 24, 2010 5:17 pm 
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Joined: Tue Mar 22, 2005 9:18 pm
Posts: 1422
Location: Brisbane, Queensland, Australia
I had a very similar problem just last night, my problem however was tied directly to PCM audio as when I was watching a HD channel the audio when through fine. I could do a speaker-test with PCM audio and that would work, so it was directly related to a MythTV error. I played with my settings and finally got it to work, however I don't know exactly what I did.

When I first install 6.02 I had no sound such as yourself and the way I fixed it was with the settings in the General area of MythTV. With the audio page (I am going from memory here) I had the output as default, the next one I had set to the dgital output on mine it is something like iec968 0x02. The number of channels is Stereo and I have both AC3 and DTS passthrough checked. On the next page I have the internal mixer turned off.

It wasn't until I had my settings like this did my digital audio work at all.

Good Luck

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Girkers


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PostPosted: Wed Mar 24, 2010 5:36 pm 
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Joined: Sun Oct 30, 2005 7:07 pm
Posts: 72
Girkers,

Thanks for the tip. Do you have a Chaintech AV-710 also, by chance? I will try playing around some more as you did... but I think my settings are very close to what you describe.

Another thought I had was to pull the AV-710 card and try the onboard Nvidia NForce 4 audio - the K8N Neo8 Platinum board has a SPDIF optical output also. In the past it was not supported by linux (hence the reason for the Dragon systems having the AV-710). But now, I wonder if this device would work?

I'll post back after I try your suggestion, Girkers (iec968 0x02)


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 Post subject: SOLVED!
PostPosted: Wed Mar 24, 2010 7:33 pm 
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To all weary digital audio users....

The suggestion by Girkers led me to get my digital audio pass-through working again with R6.02! I am happy to say that I am receiving Dolby Digital and PCM digital audio now through my SPDIF output to the receiver.

I kept my asound.conf file from R5.5 - it was not the problem. Initially, I had used the "LinHES Configuration" menu -> Audio Settings. In there, I had chosen ALSA sound driver, Type digital, and Finish. This changed settings in the MythTv Setup -> General settings for audio, but unfortunately they did not work (so, LinHES development may want to make note of this for future LinHES versions).

To fix it, I modified the General page 3 (Audio System) a different way as suggested by Birkers and now digital audio is restored for me also.

Here so, is what I ended up with:

1) re-used working asound.conf from previous installation of Myth
2) In General (screen 3) -> Audio System I set:
Audio output device: /dev/adsp
Passthrough output device: ALSA:iec958:{ AES0 0x01 }
Max Audio Channels: Stereo
Upmix: Passive
Enable AC3 to SPDIF - checked
Enable DTS to SPDIF - checked
Aggressive Sound card buffering - unchecked

NOTE: my use of "AES0 0x01" for the Passthrough output device is specific to my system. The "0x01" maps to my card's digital output of hw:0,1. Make sure you use http://www.mythtv.org/wiki/AllensDigitalAudioHowto to find the value to use for your sound card. Also, I had to edit this value, as it was pre-populated with 0x02 to start.

NOTE: Other values for Audio output device also worked. But some that you would think would work did not, e.g. ALSA:digital.

3) General (screen 4) -> Audio Mixer
Use internal volume controls - unchecked

That's it. I hope this is helpful to others.

Thanks for your help, Girkers!


Last edited by twbutler on Sun Mar 28, 2010 12:34 pm, edited 2 times in total.


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PostPosted: Sat Mar 27, 2010 1:12 am 
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Joined: Tue Mar 22, 2005 9:18 pm
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Location: Brisbane, Queensland, Australia
Just for the record I don't have a Chaintech card, just using the onboard with the Motherboard.

Glad it worked out for you, it took me a frustrating time to work it out. Lucky my daughter was asleep and my wife at work when I was setting it up, otherwise the swear jar would have been very full. :)

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Girkers


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PostPosted: Sat Mar 27, 2010 1:21 pm 
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Joined: Fri Jun 23, 2006 10:57 am
Posts: 106
Still was odd that mine "broke" since it was working fine for a week after my last software update. I know there is a reasonable explanation but I cannot find one.

Anyway, to get it to work I did have to change it to "Stereo" from "5.1", which of course doesn't make any sense. My receiver is reporting it is getting 5.1 audio though so it works as it did before.

It was funny running mythfrontend on that setup (projector w/100" screen) since I've been running my own code the last few weeks. I like my code better. :D

Thanks for the help guys...


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 Post subject: Edited my settings
PostPosted: Sun Mar 28, 2010 12:24 pm 
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Joined: Sun Oct 30, 2005 7:07 pm
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Folks,

I worked on my Myth system more this weekend and have made more tweaks to the audio settings. The settings I posted here above originally worked if the audio was Dolby Digital or DTS, but not for plain old PCM. I modified the settings a little and got PCM to work again. So, the post above this one from me will now show the final settings which totally worked for me.

Trevor


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PostPosted: Wed Mar 31, 2010 8:04 am 
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Joined: Tue Mar 22, 2005 9:18 pm
Posts: 1422
Location: Brisbane, Queensland, Australia
To add to this issue I had just finished watching a mkv file and digital audio and when I went back to normal TV found that PCM audio no longer worked. Rebooted the computer still no good.

Changed my output device from ALSA:default to /dev/adsp as suggested in this topic and it all good again.

Thanks for the help

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Girkers


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