我想让程序使用 openal 直接使用 alsa 库通过我的 nvidia 卡的 hdmi 输出发送声音。这是我的配置：
root@localhost /root % cat /proc/asound/cards
0 [PCH ]: HDA-Intel - HDA Intel PCH
HDA Intel PCH at 0xef420000 irq 136
1 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xef080000 irq 17
root@localhost /root %
似乎没有为 Nvidia 声卡加载内核模块（Windows® 中有特定的声卡驱动程序）。如果需要，我不知道要加载哪个内核模块。
root@localhost /root % lsmod | grep snd
snd_hda_intel 36864 0
snd_hda_codec_realtek 90112 1
snd_hda_codec_generic 73728 1 snd_hda_codec_realtek
snd_hda_codec_hdmi 49152 2
snd_hda_codec 135168 4 snd_hda_intel,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek
snd_hda_core 81920 5 snd_hda_intel,snd_hda_codec,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek
snd_hwdep 16384 1 snd_hda_codec
snd_pcm 114688 4 snd_hda_intel,snd_hda_codec,snd_hda_core,snd_hda_codec_hdmi
snd_timer 32768 1 snd_pcm
snd 86016 8 snd_hda_intel,snd_hwdep,snd_hda_codec,snd_timer,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek,snd_pcm
soundcore 16384 1 snd
root@localhost /root %
所以我在 alsamixer 中取消了 spdif 输入的静音：
但声音仍然被发送到我的电脑扬声器而不是 hdmi（也许这是正常的，因为我的显卡上没有 spdif 输入线）。
我读过.asoundrc，但我不知道该选择哪个设备（HDMI 音频）：
root@localhost /root % aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
default:CARD=PCH
HDA Intel PCH, ALC887-VD Analog
Default Audio Device
sysdefault:CARD=PCH
HDA Intel PCH, ALC887-VD Analog
Default Audio Device
front:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
Front speakers
surround21:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Digital
IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=PCH,DEV=0
HDA Intel PCH, HDMI 0
HDMI Audio Output
hdmi:CARD=PCH,DEV=1
HDA Intel PCH, HDMI 1
HDMI Audio Output
hdmi:CARD=PCH,DEV=2
HDA Intel PCH, HDMI 2
HDMI Audio Output
dmix:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
Direct sample mixing device
dmix:CARD=PCH,DEV=1
HDA Intel PCH, ALC887-VD Digital
Direct sample mixing device
dmix:CARD=PCH,DEV=3
HDA Intel PCH, HDMI 0
Direct sample mixing device
dmix:CARD=PCH,DEV=7
HDA Intel PCH, HDMI 1
Direct sample mixing device
dmix:CARD=PCH,DEV=8
HDA Intel PCH, HDMI 2
Direct sample mixing device
dsnoop:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
Direct sample snooping device
dsnoop:CARD=PCH,DEV=1
HDA Intel PCH, ALC887-VD Digital
Direct sample snooping device
dsnoop:CARD=PCH,DEV=3
HDA Intel PCH, HDMI 0
Direct sample snooping device
dsnoop:CARD=PCH,DEV=7
HDA Intel PCH, HDMI 1
Direct sample snooping device
dsnoop:CARD=PCH,DEV=8
HDA Intel PCH, HDMI 2
Direct sample snooping device
hw:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
Direct hardware device without any conversions
hw:CARD=PCH,DEV=1
HDA Intel PCH, ALC887-VD Digital
Direct hardware device without any conversions
hw:CARD=PCH,DEV=3
HDA Intel PCH, HDMI 0
Direct hardware device without any conversions
hw:CARD=PCH,DEV=7
HDA Intel PCH, HDMI 1
Direct hardware device without any conversions
hw:CARD=PCH,DEV=8
HDA Intel PCH, HDMI 2
Direct hardware device without any conversions
plughw:CARD=PCH,DEV=0
HDA Intel PCH, ALC887-VD Analog
Hardware device with all software conversions
plughw:CARD=PCH,DEV=1
HDA Intel PCH, ALC887-VD Digital
Hardware device with all software conversions
plughw:CARD=PCH,DEV=3
HDA Intel PCH, HDMI 0
Hardware device with all software conversions
plughw:CARD=PCH,DEV=7
HDA Intel PCH, HDMI 1
Hardware device with all software conversions
plughw:CARD=PCH,DEV=8
HDA Intel PCH, HDMI 2
Hardware device with all software conversions
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
root@localhost /root %
此外，此列表中的 Nvidia 设备均不适用于aplay -D
root@localhost /root % aplay -Dhw:1 /usr/share/kde4/apps/kolf/sounds/blackhole.wav
aplay: main:788: No such file or directory
使用 strace 查看，它似乎试图打开一个不存在的设备文件：
root@localhost /root % strace aplay -Dhw:1 /usr/share/kde4/apps/kolf/sounds/blackhole.wav 2>&1 | grep /dev/snd
open("/dev/snd/controlC1", O_RDONLY|O_CLOEXEC) = 3
open("/dev/snd/controlC1", O_RDWR|O_CLOEXEC) = 3
open("/dev/snd/pcmC1D0p", O_RDWR|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
root@localhost /root %
这看起来很正常，因为设备 1-1 不存在：
root@localhost /root % cat /proc/asound/devices
1: : sequencer
2: [ 0] : control
3: [ 0- 0]: digital audio playback
4: [ 0- 0]: digital audio capture
5: [ 0- 1]: digital audio playback
6: [ 0- 3]: digital audio playback
7: [ 0- 7]: digital audio playback
8: [ 0- 8]: digital audio playback
9: [ 0- 0]: hardware dependent
10: [ 0- 2]: hardware dependent
11: [ 1] : control
12: [ 1- 3]: digital audio playback
13: [ 1- 7]: digital audio playback
14: [ 1- 8]: digital audio playback
15: [ 1- 9]: digital audio playback
16: [ 1- 0]: hardware dependent
33: : timer
root@localhost /root %
此外，我发现 pavucontrol 声称 HDMI 端口已拔出，而电视上有视频信号。