FAQ (archived)

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The FAQs have been reorganized. The new location of this question is FAQ

This is an unofficial Wiki-based ALSA FAQ that can be freely edited or added to by anyone. If you have some time to spare, please also take a look at those questions that have not been answered yet and answer them if you know the solution..

FAQ001: How can I see which audio [pcm], midi [seq] and mixer [ctl] devices my ALSA installation sees?

FAQ002: Can I use my old OSS apps with ALSA?

FAQ003: Nothing works at all. I tried everything!

FAQ004: My ALSA modules seem to be loaded fine but I hear no sound. Why is that?

FAQ005: Loading my driver module fails with "no such device" [or something similar]

FAQ006: Loading my driver module fails with "unresolved symbols"

FAQ007: How can I check whether ALSA works?

FAQ008: How can I see if a channel is muted in alsamixer?

FAQ009: How can I enable "digital out" on my soundcard?

FAQ010: Can I have OSS and ALSA modules loaded at the same time?

FAQ011: How can I find out whether I have OSS emulation modules loaded?

FAQ012: Where are the ALSA drivers installed?

FAQ013: How can I connect ALSA MIDI-applications?

FAQ014: Where can I talk to real people about ALSA if I have questions not answered in the FAQ or other ALSA-documentation?

FAQ015: MIDI timing is very unstable. How can I improve that?

FAQ016: My sound crackles when the system is under load. How can I improve that?

FAQ017: My usb-audio device has problems when using sample rates above 22kHz. Why's that?

FAQ018: Can I use several applications at once? The second program I try to run seems to block until the first one releases the device.

FAQ019: Is there an official FAQ?

FAQ020: "aplay -D rear <soundfile>" fails with "Invalid type for PCM rear definition" What does this error mean? How do you fix it?

FAQ021: Every time I boot my computer all volumes are at zero and all channels are muted

FAQ022: What are the relationships among devices, subdevices, PCM definitions, channels, and speakers? Does a PCM correspond to a device or a subdevice? To a channel?

FAQ023: When I try to play Enemy Territory or other games based on the Quake 3 engine, I get an "/dev/dsp: Input/output error Could not mmap /dev/dsp" message

FAQ024: How can I update the ALSA version when running a 2.6.x kernel?

FAQ025: ALSA utilities don't work unless I'm root on my Linux system. What's up with that?

FAQ026: How can I change the default ALSA device?

FAQ027: What's all this dmix/dshare/dsnoop/asym stuff? How does it work?

FAQ028: Can I play stereo files over all speakers of my 4.0, 5.1 or 7.1 surround-sound setup?

FAQ029: How can I find out whether I have the OSS sound driver modules loaded?

FAQ030: I am seeing (and hearing) xruns whenever the hard disk is accessed

FAQ031: What is a "mixer"?

FAQ032: I get "no such file or directory" errors from all alsa-utils. What's wrong?

FAQ033: Are there any VU meters available for ALSA?

FAQ034: Is there a way to get mplayer working with ALSA plug:dmix ?

FAQ035: Can I use multiple soundcards with JACK / in sync

FAQ036: I cannot record from the microphone

FAQ037: Which is the relationship between ALSA and sound daemons, like ARTS or Esound? May be possible in the future to replace ARTS and Esound by ALSA, so every program doesn't have to support different sound servers?

FAQ038: The headphones volume is independent by the master volume, so my keyboard special keys won't affect it. Is there a way to modify this behaviour?

FAQ039: How does the move to udev with the 2.6 kernels change the configuration methods?

FAQ040: How can I create a virtual device that can switch between one of several different soundcards during playback (without interruption)?

FAQ041: How can I tell ALSA to swap the left and right stereo channels on my soundcard?

FAQ042: The order of my cards changes whenever I reboot or as devices are plugged and unplugged. How can I create PCMs that refer to cards by name instead of number?

FAQ043:How come my gnome mixer panel has so many sliders in it? I only have a built in AC97 Stereo soundcard?? Where is the docs that describe each slider?

FAQ044:Is there a way to combine more than one alsa device into a single OSS compatible device? For instance a USB Microphone for capture and an onboard soundcard for output that can be accessed as a single OSS compatible device??

FAQ045:How can I find which processes are using Alsa devices?

FAQ046:How do I enable MIDI I/O (MPU401 etc.)?

FAQ047:When I use FAQ018 method to get more than one app play sound at time, all apps plays at 100% volume independently of what is set in alsamixer (or gnome-alsamixer or whichever)

FAQ048:How do I use LIRC's alsa_usb plugin for my SB Extigy/Audigy remote control?

FAQ049:How do I get AC3 surround sound with my Sound Blaster Extigy?

FAQ050:How can I make my USB device the default device upon plugin?

FAQ051:Is there an alsa plugin I can use to normalize my audio output volume?

FAQ052:How can I use alsa with shoutcast/icecast to create a "fake" sound card on one (sound-card-less) machine that I can listen to on another machine?

FAQ053:What is known to be broken or incomplete in ALSA?

FAQ054:How can I select plugins depending on the input type? Eg. having "duplicate" for Stereo sound and "copy" for 5.1.

FAQ055:How can I combine 2.0->5.1 upmixing with dmix and front/rear speaker selection?

FAQ056:I configured dmix but still get "unable to open slave" or "Device or resource busy"

FAQ057: aplay -D hw:0,0 -f U8 /usr/share/firefox/res/samples/test.wav Playing WAVE '/usr/share/firefox/res/samples/test.wav' : Unsigned 8 bit, Rate 22050 Hz, Mono aplay: set_params:896: Sample format not available -- What does this mean?

Retrieved from "http://alsa.opensrc.org/FAQ_(archived)"
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