通过 “cat /proc/asound/cards” 可以查看当前设备的声卡情况。

以笔者的平台为例：

# cat /proc/asound/cards
 0 [PL330B         ]: LINUXV4L2 - PL330B, Audio Capture #00.00
                      PL330B, Audio Capture #00.00 (Long Name)
 1 [PL330B_1       ]: LINUXV4L2 - PL330B, Audio Capture #01.00
                      PL330B, Audio Capture #01.00 (Long Name)
 2 [PL330B_2       ]: LINUXV4L2 - PL330B, Audio Capture #02.00
                      PL330B, Audio Capture #02.00 (Long Name)
 3 [PL330B_3       ]: LINUXV4L2 - PL330B, Audio Capture #03.00
                      PL330B, Audio Capture #03.00 (Long Name)
 4 [PL330B_4       ]: LINUXV4L2 - PL330B, Audio Capture #04.00
                      PL330B, Audio Capture #04.00 (Long Name)
 5 [PL330B_5       ]: LINUXV4L2 - PL330B, Audio Capture #05.00
                      PL330B, Audio Capture #05.00 (Long Name)
 6 [PL330B_6       ]: LINUXV4L2 - PL330B, Audio Capture #06.00
                      PL330B, Audio Capture #06.00 (Long Name)
 7 [PL330B_7       ]: LINUXV4L2 - PL330B, Audio Capture #07.00
                      PL330B, Audio Capture #07.00 (Long Name)
 8 [PL330B_8       ]: LINUXV4L2 - PL330B, Audio Capture #08.00
                      PL330B, Audio Capture #08.00 (Long Name)
 9 [PL330B_9       ]: LINUXV4L2 - PL330B, Audio Capture #09.00
                      PL330B, Audio Capture #09.00 (Long Name)
10 [PL330B_A       ]: LINUXV4L2 - PL330B, Audio Capture #10.00
                      PL330B, Audio Capture #10.00 (Long Name)
11 [PL330B_B       ]: LINUXV4L2 - PL330B, Audio Capture #11.00
                      PL330B, Audio Capture #11.00 (Long Name)
12 [Webcam         ]: USB-Audio - aoni Webcam
                      Sunplus IT Co aoni Webcam at usb-0000:00:14.0-1, high speed

可以看到笔者平台下共有13个主声卡。其中PL330B板占据了12个，USB摄像头占据了1个。

“cat /proc/asound/pcm” 可以看到声卡下面所有的pcm devices，显示了平台所有的playback和capture能力。

仍以笔者平台为例：

# cat /proc/asound/pcm
00-00: PCM #00 : PCM #00 : capture 3
01-00: PCM #01 : PCM #01 : capture 3
02-00: PCM #02 : PCM #02 : capture 3
03-00: PCM #03 : PCM #03 : capture 3
04-00: PCM #04 : PCM #04 : capture 3
05-00: PCM #05 : PCM #05 : capture 3
06-00: PCM #06 : PCM #06 : capture 3
07-00: PCM #07 : PCM #07 : capture 3
08-00: PCM #08 : PCM #08 : capture 3
09-00: PCM #09 : PCM #09 : capture 3
10-00: PCM #10 : PCM #10 : capture 3
11-00: PCM #11 : PCM #11 : capture 3
12-00: USB Audio : USB Audio : capture 1