linux alsa配置

1 查看系统audio设备

查看audio设备摘要信息

1	$ aplay -l

可能的输出：

**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC662 rev1 Digital [ALC662 rev1 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 7: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 8: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 9: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

查看audio详细信息

1	$ aplay -L

可能输出：

null
    Discard all samples (playback) or generate zero samples (capture)
front:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    Front speakers
surround40:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Intel,DEV=0
    HDA Intel, ALC662 rev1 Digital
    IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=NVidia,DEV=0
    HDA NVidia, HDMI 0
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=1
    HDA NVidia, HDMI 0
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=2
    HDA NVidia, HDMI 0
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 0
    HDMI Audio Output

2 配置文件

最简单的/etc/asound.conf格式如下(用户配置文件为~/.asoundrc):

1	defaults.ctl.card 0

2	defaults.pcm.card 0

3	defaults.timer.card 0

4

5	pcm.!default {

6

typehw

7

card 0

8

device 0

9

}

10

11	ctl.!default {

12

typehw

13

card 0

14

device 0

15

}

其中card和device的确定从aplay -l命令得到。对比aplaya -l的输出，可以看到上面的配置文件使用了Intel的音频设备。

2.1 设置默认输出设备

首先根据aplay -l的输出来确定声卡ID和设备ID

把Intel模拟输出作为默认audio输出设备

1	defaults.ctl.card 0

2	defaults.pcm.card 0

3	defaults.timer.card 0

4

5	pcm.!default {

6

typehw

7

card 0

8

device 0

9

}

10

11	ctl.!default {

12

typehw

13

card 0

14

device 0

15

}

另一种简化格式:

1	defaults.pcm.card 0

2	defaults.pcm.device 0

3	defaults.ctl.card 0

把Nvidia HDMI数字输出作为默认audio输出设备

1	defaults.ctl.card 1

2	defaults.pcm.card 1

3	defaults.timer.card 1

4

5	pcm.!default {

6

typehw

7

card 1

8

device 7

9

}

10

11	ctl.!default {

12

typehw

13

card 1

14

device 7

15

}

另一种简化格式:

1	defaults.pcm.card 1

2	defaults.pcm.device 7

3	defaults.ctl.card 1

3 测试audio设备

测试指定audio设备

1	$ speaker-test-D front:Intel -c2 -r44100 -FS16_LE -twav

或者

1	speaker-test-c 2 -r 48000 -D hw:1,7

测试默认audio设备

1	$ speaker-test-c2 -r44100 -FS16_LE -twav

4 调节audio设备

1	$ alsamixer -c 0 <---[声卡编号]

5 配置文件的保存和还原

1	$ alsactl store -f /var/lib/alsa/asound.state

2	$ alsactl restore -f /var/lib/alsa/asound.state

6 一些其它问题

怎样改变声卡的识别顺序

可以编辑/etc/modprobe.d/50-sound.conf文件，比如：

1	options snd slots=snd-hda-intel,snd-hda-intel

2	# u1Nb.XgOz+05oSl4:Intel Corporation

3	aliassnd-card-0 snd-hda-intel

4	# NXNs.vUieta7noB9:nVidia Corporation

5	aliassnd-card-1 snd-hda-intel

6

7	options snd-hda-intel index=1,0

这里需要关心的是最后一行的index=1,0
重启机器后使用命令 cat /proc/asound/cards 参看输出：

0 [NVidia         ]: HDA-Intel - HDA NVidia
                      HDA NVidia at 0xeb000000 irq 17
 1 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xeb300000 irq 42

ftp://download.nvidia.com/XFree86/gpu-hdmi-audio-document/gpu-hdmi-audio.html