Advanced Linux Sound Architecture/Troubleshooting
The alsa-utils package contains the alsa-info.sh script, which can be used to gather detailed data on the ALSA state.
alsa-info.sh
and share its output if you ask for help.Volume
No output
If speaker-test
produces sound but some other program does not, determine whether PulseAudio is being used:
# fuser -v /dev/snd/*
If it is, try using apulseAUR, as described in Advanced Linux Sound Architecture#PulseAudio compatibility. Alternatively, killing the PulseAudio process may cause sound to start working in the desired process.
Output is muted after reboot
Run the following command:
# alsactl restore
If the problem persists, verify that the Auto-Mute
option in alsamixer is set to Disabled
.
Volume is too low
Run alsamixer and try to increase the value of the sliders, unmuting channels if necessary. Note that if you have many sliders, you may have to scroll to the right to see any missing sliders.
If all the sliders are maxed out, and the volume is still too low, you can try running the following script to reset your codec settings:
$ wget -O hda-analyzer.py https://git.alsa-project.org/?p=alsa.git;a=blob_plain;f=hda-analyzer/run.py
Close the analyzer, and when prompted as to whether you want to reset the codecs, say "yes".
If the volume is still too low, run alsamixer again: resetting the codecs may have caused new sliders to become enabled and some of them may be set to a low value.
Volume is still too low
If you are facing low volume even after maxing out your speakers/headphones, you can give the softvol plugin a try. Add the following to /etc/asound.conf
.
/etc/asound.conf
pcm.!default { type plug slave.pcm "softvol" } pcm.softvol { type softvol slave { pcm "dmix" } control { name "Pre-Amp" card 0 } min_dB -5.0 max_dB 20.0 resolution 6 }
plug
with hw
in the above configuration.After the changes are loaded successfully, you will see a Pre-Amp
section in alsamixer. You can adjust the levels there.
- Setting a high value for
Pre-Amp
can cause sound distortion, so adjust it according to the level that suits you. - Some audio codecs may need to have settings adjusted in the HDA Analyzer (see #Volume is too low) in order to achieve proper volume without distortion. Checking the HP option under widget control in the Playback Switch (Node[0x14] PIN in the ALC892 codec, for instance) can sometimes improve audio quality and volume significantly.
Random lack of sound on startup
You can quickly test sound by running speaker-test
. If there is no sound, you may see something similar to:
ALSA lib pcm_dmix.c:1022:(snd_pcm_dmix_open) unable to open slave Playback open error: -16 Device or resource busy
If you have no sound on startup, this may be because your system has multiple sound cards, and their order may sometimes change on startup. If this is the case, try setting the default sound card.
If you use MPD and the above configuration tips do not work, try following https://mpd.wikia.com/wiki/Configuration#ALSA_MPD_software_volume_control.
Microphone
No microphone input
In alsamixer, make sure that all the volume levels are up under recording, and that CAPTURE is toggled active on the microphone (e.g. Mic, Internal Mic) and/or on Capture (in alsamixer, select these items and press space). Try making positive Mic Boost and raising Capture and Digital levels higher; this may make static or distortion, but then you can adjust them back down once you are hearing something when you record
As the pulseaudio wrapper is shown as "default" in alsamixer, you may have to press F6 to select your actual soundcard first. You may also need to enable and increase the volume of Line-in in the Playback section.
To test the microphone, run these commands (see arecord(1) for further information):
$ arecord --duration=5 --format=dat test-mic.wav $ aplay test-mic.wav
Alternatively, you can run this command:
$ arecord -vv --format=dat /dev/null
alongside alsamixer to easily identify channel which you should select and unmute.
To test a particular device, use the --device
parameter followed by the hardware PCM name in the form hw:C,D
for card C device D, or plughw:C,D
for plugged hardware. For instance:
$ arecord -vvv --format=dat --device=plughw:0,0 /dev/null
If all fails, you may want to eliminate hardware failure by testing the microphone with a different device.
For at least some computers, muting a microphone (MM) simply means its input does not go immediately to the speakers. It still receives input.
Many Dell laptops need -dmic
to be appended to the model
kernel module parameter:
options snd_hda_intel model=dell-m6-dmic
Some programs use try to use OSS as the main input software. If you have enabled the snd_pcm_oss
, snd_mixer_oss
or snd_seq_oss
kernel modules previously (they are not loaded by default), try unloading them.
See also:
- https://www.alsa-project.org/main/index.php/SoundcardTesting
- https://alsa.opensrc.org/Record_from_mic
Setting the default microphone/capture device
Some applications (Pidgin, Adobe Flash) do not provide an option to change the capture device. It becomes a problem if your microphone is on a separate device (e.g. USB webcam or microphone) than your internal sound card. To change only the default capture device, leaving the default playback device as is, you can modify your ~/.asoundrc
file to include the following:
~/.asoundrc
pcm.usb { type hw card U0x46d0x81d } pcm.!default { type asym playback.pcm { type plug slave.pcm "dmix" } capture.pcm { type plug slave.pcm "usb" } }
Replace U0x46d0x81d with your capture device's card name in ALSA. You can use arecord -L
to list all the capture devices detected by ALSA.
Internal microphone not working
First make sure the volume is enabled under the Capture
view in alsamixer. In some cases, the "Internal Microphone" is not displayed in the capture list available when pressing F4. If so, specifying the card number given by aplay -l
to start alsamixer (for example alsamixer -c 0
) can make it appear.
Audio Quality
Crackling sound through mini-jack (headphones connector)
Following Advanced Linux Sound Architecture#Simultaneous output might lead to crackling sound through headphones or external speakers. This can be fixed by muting or setting the volume to 0% on Mic. Use alsamixer
or amixer
:
$ amixer sset "Mic" 0% $ amixer sset "Mic" mute
Popping sound after resuming from suspension
You might hear a popping sound after resuming the computer from suspension. This can be fixed by editing /etc/pm/sleep.d/90alsa
and removing the line that says aplay -d 1 /dev/zero
Sound skipping during playback
Run alsamixer, and if channels exist for nonexistent output devices then disable them (e.g. alsamixer showing a center speaker but you not having one).
Poor sound quality or clipping
If you experience poor sound quality, try setting the PCM volume (in alsamixer) to a level such that gain is 0.
If snd_usb_audio
driver has been loaded, you could try to enable softvol
:
/etc/asound.conf
pcm.!default { type plug slave.pcm "softvol" } pcm.dmixer { type dmix ipc_key 1024 slave { pcm "hw:0" period_size 4096 buffer_size 131072 rate 50000 } bindings { 0 0 1 1 } } pcm.dsnooper { type dsnoop ipc_key 1024 slave { pcm "hw:0" channels 2 period_size 4096 buffer_size 131072 rate 50000 } bindings { 0 0 1 1 } } pcm.softvol { type softvol slave { pcm "dmixer" } control { name "Master" card 0 } } ctl.!default { type hw card 0 } ctl.softvol { type hw card 0 } ctl.dmixer { type hw card 0 }
Pops when starting and stopping playback
Some modules (e.g. snd_hda_intel
) can power off your sound card when it is not used. This can make an audible noise (like a crack/pop/scratch) when turning on/off your sound card. Sometimes even when moving the volume slider or opening and closing windows on some desktop environments. If you find this annoying, try modinfo your_module
and look for a module option that adjusts or disables this feature.
For example, to disable the power saving mode for the snd_hda_intel
module, add the following kernel module parameter:
options snd_hda_intel power_save=0
You may also need to disable power saving for the audio card controller:
options snd_hda_intel power_save=0 power_save_controller=N
You may also have to unmute the 'Line' ALSA channel for this to work. Any value will do (other than '0' or something too high). For example, on an onboard VIA VT1708S (using the snd_hda_intel
module) these cracks occurred even when power_save
was set to 0. Unmuting the 'Line' channel and setting a value of '1' solved the problem.
See https://docs.kernel.org/sound/designs/powersave.html
Hardware and Cards
Verifying output parameters
Check the contents of /proc/asound/cardX/pcmYp/subZ/hw_params
, where X
, Y
, and Z
are system dependent.
In order to find this file, execute the following command while outputting anything via ALSA:
$ find /proc/asound/ -name hw_params | xargs -I FILE grep -v -l "closed" FILE | grep '/proc/asound/card./pcm.p/sub./hw_params'
If nothing is playing there should be no results.
Here is an example output for audio with a bit depth of 24 bits and a sampling frequency of 44.1 kilohertz:
$ cat /proc/asound/card1/pcm0p/sub0/hw_params
access: RW_INTERLEAVED format: S24_3LE subformat: STD channels: 2 rate: 44100 (44100/1) period_size: 5513 buffer_size: 22050
More info is available in the ALSA documentation.
Error 'Unknown hardware' appears after kernel update
The following messages may be displayed during ALSA's initialization:
Unknown hardware "foo" "bar" ... Hardware is initialized using a guess method /usr/bin/alsactl: set_control:nnnn:failed to obtain info for control #mm (No such file or directory)
or:
Found hardware: "HDA-Intel" "VIA VT1705" "HDA:11064397,18490397,00100000" "0x1849" "0x0397" Hardware is initialized using a generic method /usr/bin/alsactl: set_control:1328: failed to obtain info for control #1 (No such file or directory) /usr/bin/alsactl: set_control:1328: failed to obtain info for control #2 (No such file or directory) /usr/bin/alsactl: set_control:1328: failed to obtain info for control #25 (No such file or directory) /usr/bin/alsactl: set_control:1328: failed to obtain info for control #26 (No such file or directory)
Simply store ALSA mixer settings again:
# alsactl -f /var/lib/alsa/asound.state store
It may be necessary configure ALSA again with alsamixer
Fix wrong audio pin mapping
If the mappings to your audio pins(plugs) do not correspond but ALSA works fine, you could try HDA Analyzer -- a pyGTK2 GUI for HD-audio control can be found at the ALSA wiki. Try tweaking the Widget Control section of the PIN nodes, to make microphones IN and headphone jacks OUT. Referring to the Config Defaults heading is a good idea.
python
in the run.py
file with python2
to point the script to the Python 2 version. Then make the script executable and run it.S/PDIF output does not work
S/PDIF (IEC958) utilizes two modes:
- Audio mode is digital PCM signal, so the receiver just converts the data with digital-to-analog converter (DAC).
- Non-audio mode is an encoded bitstream, so the receiver must decode the data first, and put it to DAC then. Dolby Digital and DTS Digital Surround are examples of encoded bitstream formats.
ALSA should detect appropriate mode automatically, but if it fails, you can force the mode with iecset(1) (on
—audio, off
—non-audio):
# iecset audio on # iecset audio off
For more information, see DigitalOut.
No sound when S/PDIF video card is installed
Discover available modules and their order:
$ cat /proc/asound/modules
0 snd_hda_intel 1 snd_ca0106
Disable the undesired video card audio codec in /etc/modprobe.d/modprobe.conf
:
/etc/modprobe.d/modprobe.conf
install snd_hda_intel /bin/false
If both devices use the same module then you can use the enable
kernel module parameter from snd_hda_intel module; it is an array of booleans that can enable/disable the desired sound card.
options snd_hda_intel enable=1,0
Wrong sound card model type
Although ALSA detects your soundcard through the BIOS, at times ALSA may not be able to recognize your model type. The sound card chip can be found in alsamixer (e.g. ALC662) and the model can be set as kernel module parameter:
options snd_hda_intel model=MODEL
Intel onboard sound
No headphone sound with onboard intel sound card
With some laptops, you may need to add the following kernel module parameter:
options snd_hda_intel model=MODEL
Where MODEL is any of the ones listed in the kernel documentation, but check that it is the correct version of that document for your kernel version.
To know your chip name type the following command (with * being corrected to match your files). Note that some chips could have been renamed and do not directly match the available ones in the file.
$ grep Codec /proc/asound/card*/codec*
HDMI
HDMI Output does not work
The procedure described below can be used to test HDMI audio. Before proceeding, make sure you have enabled and unmuted the output with alsamixer
.
Connect your PC to the Display via HDMI cable and enable the display with xrandr.
Use aplay -l
to discover the card and device number. For example:
$ aplay -l
**** List of PLAYBACK Hardware Devices **** card 0: SB [HDA ATI SB], device 0: ALC892 Analog [ALC892 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: SB [HDA ATI SB], device 1: ALC892 Digital [ALC892 Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: Generic [HD-Audio Generic], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0
Send sound to the device. Following the example in the previous step, you would send sound to card 1
, device 3
:
$ aplay -D plughw:1,3 /usr/share/sounds/alsa/Front_Center.wav
If aplay does not output any errors, but still no sound is heard, "reboot" the receiver, monitor or tv set. Since the HDMI interface executes a handshake on connection, it might have noticed before that there was no audio stream embedded, and disabled audio decoding. If you are using a standalone window manager, you may need to have sound playing while plugging in the HDMI cable.
mplay and other application could be configured to use special HDMI device as audio output. But flashplugin could only use default device. The following method is used to override default device. But you need to change it back when your TV is disconnected from HDMI port.
If the test is successful, create or edit your ~/.asoundrc
file to set HDMI as the default audio device.
~/.asoundrc
pcm.!default { type hw card 1 device 3 }
Or if the above configuration does not work try:
~/.asoundrc
defaults.pcm.card 1 defaults.pcm.device 3 defaults.ctl.card 1
Or if you alternatively succeed with
$ speaker-test -Dplug:hdmi
for your HDMI or DisplayPort port the following configuration will work (successfully tested on Lenovo ThinkPad T430s):
~/.asoundrc
pcm.!default { type plug slave.pcm "hdmi" }
HDMI 5.1 sound goes to wrong speakers
Sound can be redirected to the intended speakers using ALSA's remap
function.
/etc/asound.conf
pcm.!hdmi-remap { type asym playback.pcm { type plug slave.pcm "remap-surround51" } } pcm.!remap-surround51 { type route slave.pcm "hw:0,3" ttable { 0.0= 1 1.1= 1 2.4= 1 3.5= 1 4.2= 1 5.3= 1 } }
Applications
SDL: No sound with SDL applications
If you get no sound using SDL based applications, try setting the environment variable SDL_AUDIODRIVER
to alsa
.
OpenAL: No sound in applications that use OpenAL
OpenAL defaults to PulseAudio. To instruct it to try ALSA first:
/etc/openal/alsoft.conf
drivers=alsa,pulse
Others: Generic application problems
For other applications who insist on their own audio setup, e.g., XMMS or MPlayer, you would need to set their specific options.
For MPlayer or mpv, add the following line to the respective configuration file:
ao=alsa
Eg. for XMMS2, go into their options and make sure the sound driver is set to ALSA, not oss.
To do this in XMMS:
- Open XMMS
- Options > Preferences.
- Choose the ALSA output plugin.
For applications which do not provide a ALSA output, you can use aoss from the alsa-oss package. To use aoss, when you run the program, prefix it with aoss
, e.g.:
aoss realplay
pcm.!default{ ... } doesnt work for me anymore. but this does:
pcm.default pcm.dmixer
Other Issues
Simultaneous playback problems
If you are having problems with simultaneous playback, and if PulseAudio is installed, its default configuration is set to "hijack" the soundcard. Some users of ALSA may not want to use PulseAudio and are quite content with their current ALSA settings. One fix is to edit /etc/asound.conf
and comment out the following lines:
# Use PulseAudio by default pcm.!default { type pulse fallback "sysdefault" hint { show on description "Default ALSA Output (currently PulseAudio Sound Server)" } }
Commenting the following out also may help:
ctl.!default { type pulse fallback "sysdefault" }
This may be a much simpler solution than completely uninstalling PulseAudio.
Effectively, here is an example of a working /etc/asound.conf
:
pcm.dmixer { type dmix ipc_key 1024 ipc_key_add_uid 0 ipc_perm 0660 } pcm.dsp { type plug slave.pcm "dmix" }
/etc/asound.conf
file was intended for and used successfully with a global MPD configuration. See #Problems with availability to only one user at a time.dmix
to work with vanilla ALSA, see the upstream documentation. In particular, you probably want to replace dsp
in the above config with !default
. Also, if you notice this causes certain applications to skip while playing (i.e. sound "glitchy"), and complain about underrun occurring, you may want to tweak the slave.buffer_size
inside pcm.dmixer
.Removing old ALSA state file (asound.state)
The alsa-utils package provides alsa-store.service
which automatically stores the current ALSA state to /var/lib/alsa/asound.state
upon system shutdown. This can be problematic for users who are trying to reset their current ALSA state as the asound.state
file will be recreated with the current state upon every shutdown (e.g., attempting to remove user-defined channels from the mixer). The alsa-store.service
service may be temporarily disabled by creating the following empty file:
# mkdir -p /etc/alsa # touch /etc/alsa/state-daemon.conf
The presence of state-daemon.conf
prevents alsa-store.service
from saving asound.state
during shutdown. After disabling this service, the asound.state
file may be removed as such:
# rm /var/lib/alsa/asound.state
After rebooting, the previous ALSA state should be lost and the current state should be reset to defaults. Re-enable alsa-store.service
by deleting the condition file we created:
# rm /etc/alsa/state-daemon.conf
On the next shutdown, the asound.state
file should be recreated with ALSA defaults. The file may also be generated immediately using:
# alsactl store
If you want to clean ALSA state without rebooting, you can use rmmod
to remove the sound driver module, then manually delete the unwanted entries in asound.state
, and then use modprobe
to reinstall the sound driver module.
Problems with availability to only one user at a time
You might find that only one user can use the dmixer at a time. This is probably ok for most, but for those who run mpd as a separate user this poses a problem. When mpd is playing a normal user cannot play sounds though the dmixer. While it is quite possible to just run mpd under a user's login account, another solution has been found. Adding the line ipc_key_add_uid 0
to the pcm.dmixer
block disables this locking. The following is a snippet from asound.conf
, the rest is the same as above.
... pcm.dmixer { type dmix ipc_key 1024 ipc_key_add_uid 0 ipc_perm 0660 slave { ...
Crackling/popping on Dell laptops
Check if you have i8kutilsAUR installed and if anything (e.g. i8kmon.service
) is reading or writing to the interface exposed by the module, as i8kutils BIOS system calls block the kernel for a moment on some systems. See warning in Fan speed control#Dell laptops for more details.
Message Signaled Interrupts
Message Signaled Interrupts (MSI) on HD Audio cards are controlled by the enable_msi
option of the snd_hda_intel
module. Whether it should be enabled or not hardly depends on the hardware. In the case of wrong autodetection different kinds of bad things could happen: erroneous disablement might lead to the sound card is not detected, erroneous enablement might lead to poor audio quality (stuttering) or even kernel lockup. To check the MSI capability status, run lspci -vv -nn -d ::0403
with root user privileges.
::0403
here means
Audio device subclass of the Multimedia controller PCI device class.DMA pointer
Click noises (crackling, popping) on input and/or output of a HD Audio card might be caused by DMA position problem. Try to change the position_fix
option of the snd_hda_intel
module.