[mythtv-users] ac3 passthrough problems

[Glen Ditchfield]

On Sat, 2006-09-30 at 16:57 -0400, Richard Krehbiel wrote:
> I'm building a mythtv system now (about as slowly as anyone possibly
> can), and I'm stumped on the S/PDIF problem.
> 
> I have an MSI K9NGM2-FID - Socket AM2, nVidia GeForce 6150, and I'm
> using on-board sound with Intel HDA drivers (snd-intel-8x0).  I
> installed Fedora Core 5, current updates...

I'm in much the same position, right down to the "slowly" part.  My system is 
an MSI K8NGM2 (the Socket 939 variant) with a GeForce 6150, nForce 430, and a 
Realtek ALC880, running Ubuntu 6.06 and alsa 1.0.10.  "aplay -l" prints
    **** List of PLAYBACK Hardware Devices ****
    card 0: NVidia [HDA NVidia], device 0: ALC880 Analog [ALC880 Analog]
      Subdevices: 1/1
      Subdevice #0: subdevice #0
    card 0: NVidia [HDA NVidia], device 2: ALC880 Digital [ALC880 Digital]
      Subdevices: 1/1
      Subdevice #0: subdevice #0
The output of "aplay -L" is identical to his.

A file in my /etc/modprobe.d directory contains 
    alias snd-card-0 snd_hda_intel
    options snd-card-0 index=0
    options snd_hda_intel index=0
    options snd_hda_intel model=3stack-digout

In alsamixer, "IEC958" is not muted.  (I don't see a graph bar above 
it.)  "PCM" is set to 90, "Surround", "Center", and "LFE" are set at 100, "PC 
Speak" is set at 97, and none are muted.  "Channel" is set to "6ch".  
The "Playback" view also includes "Headphon", "Front 
Mi", "Line", "CD",  "Mic", and three "Input So" devices, which seems weird to 
me...

I used "speaker-test" to test sound with no .asoundrc file.  
- "speaker-test -c2" produces hisses from my front left and front right 
speakers in turn, as expected.
- "speaker-test -c6" prints messages ending in "0 - Front Left", and pauses 
forever.
- "speaker-test -Dspdif" prints "Playback open error: -2,No such file or 
directory" repeatedly.  Note that "aplay -L" output included a line that 
said "spdif 'cards.pcm.iec958'".  Can anyone suggest what file it wants to 
open -- something under /dev/snd, perhaps?
- "aplay /usr/share/sounds/alsa/Front_Left.wav" produces sound on all six 
speakers.  Is that what should happen?
- "aplay /usr/share/sounds/alsa/Front_Left.wav -Dspdif" produces the error 
message "aplay: main:544: audio open error: No such file or directory".

I tried the .asoundrc file from 
http://www.mythtv.org/wiki/index.php/Configuring_Digital_Sound, modified so 
that pcm.digital-hw contains "device 2".  With that set-up,
- "speaker-test -c6 -Dmixed-analog" produces hisses from the front left and 
right speakers.  Speaker-test *claims* that it is sending sound to the other 
four speakers, but I hear nothing.  The display on my receiver shows "PCM 48" 
when the left and right front are hissing, and nothing when the other four 
speakers should be taking their turns.  The display also suggests that the 
receiver is only getting left, right, center, and subwoofer channels.
- "speaker-test -c6 -Dmixed-digital" produces a hiss on the front left 
speaker, a hideous noise on the front right, and silence on the other four.