[mythtv-users] Strange Audio Problem 0.25

[Igor Cicimov]

On Wed, Jun 13, 2012 at 2:02 PM, Igor Cicimov <icicimov at gmail.com> wrote:

>
>
> On Wed, Jun 13, 2012 at 1:43 PM, jr <jraymyth at gmail.com> wrote:
>
>> On Tue, Jun 12, 2012 at 11:03 PM, Igor Cicimov <icicimov at gmail.com>
>> wrote:
>> > Did you try with "ALSA:hdmi:CARD=NVidia,DEV=3" or DEV=7 in the audio
>> setup?
>> > Sorry fot top post im typing this on my phone. If not available as
>> selection
>> > i think you can manually edit it.
>> >
>>
>> Hmmm.  This is confusing.  Using 7 in that line resulted in a no
>> device found error.  But it got me wondering, so I went thru all of my
>> listed devices with DEV=7, and found one that works.
>>
>> ALSA:dmix:CARD=NVidia,DEV=7
>>
>>
One other thing that comes to mind ... Do you have the "Software mixer"
option ticked or not?

Igor

> This is good, but I dont understand why the HDMI line does not.
>>
>> I have an
>> ALSA:hdmi:CARD=NVidia,DEV=0
>> ALSA:hdmi:CARD=NVidia,DEV=1*
>> ALSA:hdmi:CARD=NVidia,DEV=2
>> ALSA:hdmi:CARD=NVidia,DEV=3
>>
>> *A connection is found by MythTV.  Clicking "Test" yields the test
>> hiss in alternating speakers.  No sound when playing a recording.
>>
>> Also:
>> ALSA:hw:CARD=NVidia,DEV=3
>> ALSA:hw:CARD=NVidia,DEV=7**
>> ALSA:hw:CARD=NVidia,DEV=8
>> ALSA:hw:CARD=NVidia,DEV=9
>> **A connection is found by MythTV.  Clicking "Test" yields the test
>> hiss in alternating speakers.  I hear a fast fluttering sound when
>> playing a recording.
>>
>> Also:
>> ALSA:plughw:CARD=NVidia,DEV=3
>> ALSA:plughw:CARD=NVidia,DEV=7**
>> ALSA:plughw:CARD=NVidia,DEV=8
>> ALSA:plughw:CARD=NVidia,DEV=9
>> **A connection is found by MythTV.  Clicking "Test" yields the test
>> hiss in alternating speakers.  I hear a fast fluttering sound when
>> playing a recording.
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>>
>
> Yep now that you mentioned it I remembered, the HDMI option was not
> working for me too. I think has something to do with the channels, format
> and sampling rate which needs to be 48KHz for the digital output (I think).
> That's why you need to choose the software mixing plugin device and not the
> hardware device it self. Then the dmix plugin probably uses the hardware
> device as slave PCM.
>
> So it goes something like this:
>
> # This is the DMIX device you chose and it uses a PCM slave called here
> "digital-hdmi"
> pcm.dmix {
>   type dmix
>   ipc_key 1235
>   slave {
>     pcm "digital-hdmi"
>     period_time 0
>     period_size 1024
>     buffer_size 4096
>     rate 48000
>   }
> }
>
> # This is the hardware device it self, Nvidia HDMI, which is
> card=1,device=7 in your case
> # and is being used in the above dmix device as slave
> pcm.digital-hdmi {
>   type hw
>   card 1
>   device 7
> }
>
>
> Please note that this is from my understanding of how ALSA works :) It's
> little bit complicated and I'm sure you can get much better explanation
> from some of the audio experts here like Jean-Yves. I would also appreciate
> if they correct me if I'm wrong so we both learn something too :)
>
> Igor
>
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