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Audio not being captured on PVR-250
http://forum.linhes.org/viewtopic.php?f=2&t=19385		 Page 1 of 1
Author:  Das Hammer [ Thu Jan 01, 2009 7:39 am ]
Post subject:  Audio not being captured on PVR-250
Searched around for "audio and pvr", got a lot of threads about the tinny audio problem, but this one is different. I am not getting any sound in the recordings (including live tv) from my pvr-250.

Ok, so first things first, let's check the audio connections. Yes, it is confirmed working. Pulled the audio cable from the pvr-250 and plugged it into the a/v receiver directly. Got sound. Hooked the cables back up to the pvr-250, booted into Windows, fired up MediaPortal and got sound there from the pvr-250 card. So, it is definitely connected properly and there is definitely audio being sent to the pvr-250.

What about sound in general on the rest of the system? I have digital audio output enabled per the instructions in the very informative R5.5 hints and hazards. No sound with music yet, but not worried too much about that at the moment. Working AC3 and DTS passthrough coming in while watching movies or ATSC channels.

I have the same problem with capturing analog audio/video on my Nova Shttp://mysettopbox.tv/phpBB2/viewtopic.php?t=19344. So, it has to be a sound setting somewhere that affects the input. I checked alsamixer and cranked all of the capture settings up just to make sure I was covered. Still nothing.


Not sure what else to try. Any suggestions??
Author:  cecil [ Mon Jan 05, 2009 2:23 am ]
Post subject: 
With the 250, the audio and video are muxed in the same stream. There is not need to configure ALSA for capture, etc.
Author:  Das Hammer [ Tue Jan 27, 2009 8:39 am ]
Post subject: 
Thanks for your reply, cecil.

------------

After some more experimenting, it seems the problem is somehow related to AC3 pass through.

My A/V receiver is connected to the computer via coaxial s/pdif only. Anything going to the A/V receiver must go through this cable.

I selected AC3 passthrough on the Utilities/Setup -> Setup -> General section. AC3 passthrough works brilliantly for ATSC channels.
If I turn OFF this passthrough I still get audio from ATSC channels, but it is sent as PCM rather than AC3. However, I THEN could get audio from my STB channels via the PVR-250. Yay!

----------------

Being how I am, I just can't live with decoded AC3 coming from the Myth box and would rather have the pure AC3 stream. The next test is going to be connecting a second audio output from the sound card's line-out jack to the a/v receiver. This should only get picked up by the a/v receiver when there is no digital audio present (whenever I'm watching channel captured by the pvr-250).

It sure seems like there should be a better way of doing this, but I have yet to run across it. I thought, perhaps, the default output should be alsa:spdif, but if I remember correctly, that ended up causing havoc when AC3 was getting passed through.

----------------

I'd rather use a DVB-S card and skirt this whole issue, but ever since they changed MythTV way back when to NOT use vpid/apid to tune DVB channels, it is impossible to tune a few particular channels I enjoy.
Author:  knappster [ Tue Jan 27, 2009 1:54 pm ]
Post subject: 
What are your other audio settings in myth? I have a similar setup to yours, and I have both working through the spdif cable. In the menu there is an option for something like maximum number of speakers or similar and it had to be set to 2 otherwise I wouldn't get audio (I think). I'll double check my settings later tonight to verify this.
Author:  Das Hammer [ Tue Jan 27, 2009 3:05 pm ]
Post subject: 
Off the top of my head, I know that that the number of maximum audio channels is set to "stereo" which sounds like what you are describing, knappster.

The other settings I will have to look at again when I get home.

Are you running 5.5?
Author:  slowtolearn [ Tue Jan 27, 2009 6:58 pm ]
Post subject: 
Do the settings in this post help?
Author:  Das Hammer [ Tue Jan 27, 2009 7:17 pm ]
Post subject:  Rectified....somehow???!
Ok, I did a fresh install of 5.5 tonight after getting home.

I don't know what I did differently this time to get it working, but I now have AC3 passthrough working on ATSC channels and I have the audio captured from the PVR-250 coming through the s/pdif. :lol: I'm standing here beside myself.

So, instead of leaving it at that...I'm going to list my config just in case someone else (or maybe even myself down the road) needs to look at it.

I'm using an Asus M2N-E mainboard which has an AD1988B onboard audio chip. It also has s/pdif output with a coax connector already affixed to the board.

In alsamixer I had to UNmute the IEC958 control (as usual) and I also cranked the PCM control all the way up. ( don't forget to save the alsamixer settings using #alsactl store ).

In the frontend: utilities/setup -> setup -> general this is what I have set:

Audio Output Device: ALSA:default
Passthrough output device: ALSA:iec958:{ AES0 0x02 }
(this was the only selectable option other than "default")

Max Audio Channels is set to "Stereo" and upmix is set to Passive.
Enable AC3 to SPDIF passthrough is checked
Enable DTS to SPDIF passthrough is checked
Use Internal Volume Controls is Checked

Mixer Device: ALSA:default
Mixer Controls: PCM

Master Mixer Volume and PCM Mixer volume both cranked up

--------------------------------------

Thanks, fellas, for giving me some hope to get this thing working again like it should.
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