aplay/arecord:
playback:
aplay -D default xxx.wav
list cards & devices:
aplay -l
record:
aplay -C -D defaut -d 10 -f S16_LE -r 48000 -c 2 -t wav xxx.wav
arecord -D defaut -d 10 -f S16_LE -r 48000 -c 2 -t wav xxx.wav
amixer:
show all controls for given card:
amixer -c 0 controls
amixer -Dhw:2 controls
get control contents for one control:
amixer -c 2 cget numid=1
set control contents for one control:
amixer -c 0 cset numid=1,iface=MIXER,name="Master Volume" 50
amixer -c 0 cset name="Master Volume" 50
/proc
list cards:
cat /proc/asound/cards
list devices:
cat /proc/asound/devices
ls -l /dev/snd
list pcm:
cat /proc/asound/pcm
list all devices for given card:
ls -l /proc/asound/card0
list information for given card & pcm & substream
cat /proc/asound/card0/pcm0p/sub0/info
card*/pcm*/info
- The general information of this PCM device: card #, device #, substreams, etc.
card*/pcm*/xrun_debug-
This file appears when
CONFIG_SND_DEBUG=yandCONFIG_PCM_XRUN_DEBUG=y. This shows the status of xrun (= buffer overrun/xrun) and invalid PCM position debug/check of ALSA PCM middle layer. It takes an integer value, can be changed by writing to this file, such as:# echo 5 > /proc/asound/card0/pcm0p/xrun_debug
The value consists of the following bit flags:
- bit 0 = Enable XRUN/jiffies debug messages
- bit 1 = Show stack trace at XRUN / jiffies check
- bit 2 = Enable additional jiffies check
When the bit 0 is set, the driver will show the messages to kernel log when an xrun is detected. The debug message is shown also when the invalid H/W pointer is detected at the update of periods (usually called from the interrupt handler).
When the bit 1 is set, the driver will show the stack trace additionally. This may help the debugging.
Since 2.6.30, this option can enable the hwptr check using jiffies. This detects spontaneous invalid pointer callback values, but can be lead to too much corrections for a (mostly buggy) hardware that doesn’t give smooth pointer updates. This feature is enabled via the bit 2.
card*/pcm*/sub*/info- The general information of this PCM sub-stream.
card*/pcm*/sub*/status- The current status of this PCM sub-stream, elapsed time, H/W position, etc.
card*/pcm*/sub*/hw_params- The hardware parameters set for this sub-stream.
card*/pcm*/sub*/sw_params- The soft parameters set for this sub-stream.
card*/pcm*/sub*/prealloc- The buffer pre-allocation information.
card*/pcm*/sub*/xrun_injection- Triggers an XRUN to the running stream when any value is written to this proc file. Used for fault injection. This entry is write-only.