Hello ALSA users,
I've recently been playing with a n-Vidia NVS 510 (GK107) which has four
display port outputs. The idea is to connect each output to a different
monitor with potentially different resolutions and just run a fullscreen
mplayer instance over them.
By using the propietary nvidia driver with a stock Ubuntu 12.04.3 it is
possible to create four independent screens on the same display.
However, the audio is not working completely.
The setup is the following, relevant packages and versions:
linux-image-3.2.0-56-lowlatency 3.2.0-56.58
libasound2 1.0.25-1ubuntu10.2
nvidia-319-updates 319.32-0ubuntu0.0.1
PCI information:
01:00.0 VGA compatible controller: NVIDIA Corporation Device 0ffd (rev a1) (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device 0967
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at f6000000 (32-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at f0000000 (64-bit, prefetchable) [size=32M]
I/O ports at e000 [size=128]
[virtual] Expansion ROM at f7000000 [disabled] [size=512K]
Capabilities: <access denied>
Kernel driver in use: nvidia
Kernel modules: nvidia_319_updates, nouveau, nvidiafb
01:00.1 Audio device: NVIDIA Corporation Device 0e1b (rev a1)
Subsystem: Hewlett-Packard Company Device 0967
Flags: bus master, fast devsel, latency 0, IRQ 17
Memory at f7080000 (32-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: snd_hda_intel
Kernel modules: snd-hda-intel
Contents of /proc/asound/cards while running the X server:
0 [PCH ]: HDA-Intel - HDA Intel PCH
HDA Intel PCH at 0xf7630000 irq 73
1 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xf7080000 irq 17
2 [NVidia_1 ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xf5080000 irq 18
Note that there are two PCIe cards. But now I'm focusing only on the
first one. The reported ALSA devices for the first card (aplay -L) are:
hdmi:CARD=NVidia,DEV=0
HDA NVidia, HDMI 0
HDMI Audio Output
hdmi:CARD=NVidia,DEV=1
HDA NVidia, HDMI 1
HDMI Audio Output
hdmi:CARD=NVidia,DEV=2
HDA NVidia, HDMI 2
HDMI Audio Output
hdmi:CARD=NVidia,DEV=3
HDA NVidia, HDMI 3
HDMI Audio Output
dmix:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
Direct sample mixing device
dmix:CARD=NVidia,DEV=7
HDA NVidia, HDMI 1
Direct sample mixing device
dmix:CARD=NVidia,DEV=8
HDA NVidia, HDMI 2
Direct sample mixing device
dmix:CARD=NVidia,DEV=9
HDA NVidia, HDMI 3
Direct sample mixing device
dsnoop:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
Direct sample snooping device
dsnoop:CARD=NVidia,DEV=7
HDA NVidia, HDMI 1
Direct sample snooping device
dsnoop:CARD=NVidia,DEV=8
HDA NVidia, HDMI 2
Direct sample snooping device
dsnoop:CARD=NVidia,DEV=9
HDA NVidia, HDMI 3
Direct sample snooping device
hw:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=7
HDA NVidia, HDMI 1
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=8
HDA NVidia, HDMI 2
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=9
HDA NVidia, HDMI 3
Direct hardware device without any conversions
plughw:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
Hardware device with all software conversions
plughw:CARD=NVidia,DEV=7
HDA NVidia, HDMI 1
Hardware device with all software conversions
plughw:CARD=NVidia,DEV=8
HDA NVidia, HDMI 2
Hardware device with all software conversions
plughw:CARD=NVidia,DEV=9
HDA NVidia, HDMI 3
Hardware device with all software conversions
According to the official NVidia documentation [1], this card can
reproduce as many concurrent audio streams as active (i.e. connected)
outputs. And, theroetically, I can use hw:1,3 hw:1,7 hw:1,8 and hw:1,9
as outputs.
[1] http://http.download.nvidia.com/XFree86/gpu-hdmi-audio-document/gpu-hdmi-audio.html
Now the fun part. I have two displays connected so Xorg creates two
screens 0.0 and 0.1. And I try all audio outputs to find the correct
one:
mplayer -display :0.1 -vo vdpau -ao alsa:device=hw=1.3 sample.mp4
mplayer -display :0.1 -vo vdpau -ao alsa:device=hw=1.7 sample.mp4
mplayer -display :0.1 -vo vdpau -ao alsa:device=hw=1.8 sample.mp4
mplayer -display :0.1 -vo vdpau -ao alsa:device=hw=1.9 sample.mp4
All of the above commands have the same result: video displaying on the
TV attached to display 0.1 and audio sounding on the TV connected to
display 0.0.
After some other experiments, I noticed that there is a correspondence
in physical outputs between the Xorg and ALSA points of view. The
"port_id" field in /proc/asound/card1/eld#0.? matches the information
reported by the nvidia-settings utility:
$ grep port_id /proc/asound/card1/eld#0.?
/proc/asound/card1/eld#0.0:port_id 0x80000
/proc/asound/card1/eld#0.1:port_id 0x10000
/proc/asound/card1/eld#0.2:port_id 0x20000
/proc/asound/card1/eld#0.3:port_id 0x40000
$ nvidia-settings -n -c :0 -q EnabledDisplays
Attribute 'EnabledDisplays' (avgw1:0.0): 0x00010000.
'EnabledDisplays' is a bitmask attribute.
'EnabledDisplays' is a read-only attribute.
'EnabledDisplays' can use the following target types: X Screen, GPU.
Attribute 'EnabledDisplays' (avgw1:0.1): 0x00020000.
'EnabledDisplays' is a bitmask attribute.
'EnabledDisplays' is a read-only attribute.
'EnabledDisplays' can use the following target types: X Screen, GPU.
When I add more simultaneous videos to the other screens, other weird
things may happen. But listening different audio streams over different
outputs is possible. Therefore I have two questions:
1. Is it possible to create an alias or somehow "virtual" audio device
where I can configure the output using the "port_id" information
previously mentioned? There is a PCM route plugin, but I'm not
sure about its possibilities or if appropriate.
2. Otherwise, is it an ALSA configuration at all or is more related to
the nvidia propietary driver?
My apologies for the lengthy message and thank you for reading up to
this point.
Best regards.
--
Isaac Jurado
OmniAccess S.L.
Parque Tecnológico ParcBit
Edificio W, 2ª planta
07121, Palma de Mallorca
Baleares, Spain
Phone +34 971 221 979
Fax +34 971 221 978
http://www.omniaccess.com
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