[mythtvnz] Audio on HDMI NVidia Card

[David Kirk]

Hi Stephen,

>>When I watch live TV, I only get sound from the centre speaker.  This
>>is not so good.
>>
>>Worse luck.  When I load up a web browser (Chromium) and try to watch
>>a Youtube clip or TV on demand I get no audio at all.
>>
>>Card 0, device 7 is the one that seems to work.  I can test it with
>>speaker-test -c 2 -D hw:0,7 and I get this.
>>
>>speaker-test 1.0.25
>>
>>Playback device is hw:0,7
>>Stream parameters are 48000Hz, S16_LE, 2 channels
>>Using 16 octaves of pink noise
>>Rate set to 48000Hz (requested 48000Hz)
>>Buffer size range from 64 to 16384
>>Period size range from 32 to 8192
>>Using max buffer size 16384
>>Periods = 4
>>was set period_size = 4096
>>was set buffer_size = 16384
>> 0 - Front Left
>> 1 - Front Right
>>Time per period = 5.639946
>>
>>I'm getting noise from both those speakers.  I can't seem to get 5.1
>>sound using speaker-test, but for web audio 2 channels should be fine.

> For a start, I would recommend that you normally use the "plughw"
> devices, rather than "hw".  The "plughw" ones will use all available
> means in ALSA to convert whatever input they are given to a format
> that the corresponding "hw" device will be able to handle.  That means
> for example, if you play a video file with 11025 Hz audio, it will
> work, as it will be converted to 22050 Hz or 44100 Hz which the
> hardware can normally do, or even resampled to 48000 Hz if necessary.
>
> Second, I presume you have found alsamixer?  If not, run it from a
> terminal and make sure you have all the right inputs and outputs
> enabled and set to full volume.
>
> Third, in 12.04 you will normally have Pulse Audio installed as well
> as ALSA.  I found that when I moved from 11.04 to 12.04 on my laptop,
> I had to also fiddle with the Pulse mixer settings along with
> alsamixer to make things work.  But you may already have Pulse in
> 11.10 - I never used that version so I am not sure.  I used the Pulse
> mixer applet from xfce4.

I have had some success.  I was reading the documentation about
.asoundrc http://www.alsa-project.org/main/index.php/Asoundrc#dmix.  I
copied the configuration it has for the dmix plugin and changed it to
use device 0,7.  Did some testing and I get audio in MythTV, vlc and
on YouTube.  Even Live TV seems to be working with 5.1 channels.

I tried using plughw as you suggested.  The speaker-test worked, but I
couldn't figure out how to adapt the .asoundrc file to use it so I'm
sticking with what I've got for now.

I did forget to mention a few things in my original post.  First, I
have been in to alsamixer and it only shows 2 spdif outputs.  Both are
unmuted, but there doesn't seem to be any controls to adjust the
volume.  I guess that isn't necessary.

My box is a frontend and backend.  I've gone in to the frontend audio
setup and told it to use ALSA:plughw:CARD=NVidia,DEV=7.  On the second
page I had do use the software mixer.

I don't seem to have Pulse audio installed.  I don't know why, but as
long as it is working, I don't care.


Thanks for your help.

David Kirk