[mythtvnz] Audio on HDMI NVidia Card

[Stephen Worthington]

On Mon, 22 Oct 2012 12:30:53 +1300, you wrote:

>Hi,
>
>I spent yesterday upgrading my Mythbuntu box from 11.10 to 12.04.  I
>had a few problems that I managed to fix, but I still have 2
>outstanding issues with audio.
>
>I have an NVidia GT 520 video card and that plugs in to the HDMI input
>on my TV.  My TV has an optical audio cable that goes to the home
>theatre system.
>
>01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [GeForce
>GT 520] (rev a1)
>01:00.1 Audio device: NVIDIA Corporation HDMI Audio stub (rev a1)
>
>After lots of experimentation yesterday I managed to get it to work
>with MythTV.  When I watch a recording I seem to be getting sound from
>all of the 5.1 channels.  This is good.
>
>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.
>
>If I run aplay -l I see this.
>
>**** List of PLAYBACK Hardware Devices ****
>card 0: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
>card 0: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
>
>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.
>
>I've been searching all day for something to fix my problems, but I'm
>not getting anywhere.  Does anyone have a similar system that is
>working for them?  Any ideas how to fix my system?  It used to work in
>Mythbuntu 11.10.
>
>
>Thanks
>
>David Kirk

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.