S/PDIF output has all channels but center?

[bnorman]

Ok, I'm stumped. When I play a 5.1 AC3 or DTS file with mplayer ("hwac3" passthrough) in Fedora 10, I get all channels except center. I know the center speaker works because I can play through it from other sources. Motherboard is an eVGA NForce 730i. I have tried specifying "options snd_hda_intel model=6stack-dig" with identical results.

I've beat my head against this for hours. Any suggestions would be welcome!

Thanks,
Ben

motherboard sound in lspci:

00:08.0 Audio device: nVidia Corporation MCP79 High Definition Audio (rev b1)

motherboard sound in dmesg:


hda_codec: Unknown model for ALC883, trying auto-probe from BIOS...
ALSA sound/pci/hda/hda_codec.c:3021: autoconfig: line_outs=4 (0x14/0x15/0x16/0x17/0x0)
ALSA sound/pci/hda/hda_codec.c:3025: speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
ALSA sound/pci/hda/hda_codec.c:3029: hp_outs=0 (0x0/0x0/0x0/0x0/0x0)
ALSA sound/pci/hda/hda_codec.c:3030: mono: mono_out=0x0
ALSA sound/pci/hda/hda_codec.c:3038: inputs: mic=0x18, fmic=0x19, line=0x1a, fline=0x0, cd=0x0, aux=0x0

uname:


Linux gandalf 2.6.27.15-170.2.24.fc10.x86_64 #1 SMP Wed Feb 11 23:14:31 EST 2009 x86_64 x86_64 x86_64 GNU/Linux

aplay -l:


card 0: NVidia [HDA NVidia], device 0: ALC888 Analog [ALC888 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 1: ALC888 Digital [ALC888 Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0


aplay -L:


default:CARD=NVidia
HDA NVidia, ALC888 Analog
Default Audio Device
front:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
Front speakers
surround40:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=NVidia,DEV=0
HDA NVidia, ALC888 Digital
IEC958 (S/PDIF) Digital Audio Output
null
Discard all samples (playback) or generate zero samples (capture)


running mplayer:


mplayer -ac hwac3,hwdts -ao alsa:device=iec958 test.dts
mplayer -ac hwac3,hwdts -ao alsa:device=iec958 test.ac3