I forgot the most important part in the original, the kernel!
(I hope the ASCII art doesn't get mangled)
I have been working a while trying to get a big picture of how Linux
handles sound processing and after much work I have put together this
little representation of what I have learned.
Please send me any additional comments or components that I may have
missed.
I hope it helps somebody though who may be struggling in getting
sound to work and just needs some idea of how all the parts fit
together.
There really needs to be some concise, up-to-date Wiki on Linux
sound processing and how the different applications work and
work together (or not).
Linux Sound Architecture
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
X Linux Sound Applications X
X X
X XXXXXXXXXXXXXXXXXXXXXXXXX
X X Sound Servers X
X X ESD/Arts/NASD/Pulse X
X X X
X XXXXXXXXXXXXXXXXXXXXX X
X X Third Party APIs X X
X X GStreamer X X
X X X X
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
X X OSS Compatibility API X
X ALSA Sound API XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
X X
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
X Linux Kernel X
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
X Sound Hardware X
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Ross S. W. Walker
Information Systems Manager
Medallion Financial, Corp.
437 Madison Avenue
38th Floor
New York, NY 10022
Tel: (212) 328-2165
Fax: (212) 328-2125
WWW: http://www.medallion.com <http://www.medallion.com/>
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On Tue, 2008-03-11 at 11:59 -0400, Ross S. W. Walker wrote:> I have been working a while trying to get a big picture of how Linux > handles sound processing and after much work I have put together this > little representation of what I have learned. > > Please send me any additional comments or components that I may have > missed.Some corrections (PulseAudio contains an ALSA module that can redirect audio back into PA):> Linux Sound Architecture > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > X Linux Sound Applications X > X XX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X X Third-Party APIs X X X X GStreamer/Phonon/ X Sound X X X xine-lib X Servers X X X XXXXXXXXXXXX X X X X ^ X X X X esd/aRts/NAS/JACK | X X X X | X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | X X X aoss X X OSS Compatibility API X X | X X XXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXX X PA X X X X | X X X XXX | X X X alsa-lib API X >-/ X X X XXXXXXXXX X X X> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Linux Kernel (ALSA driver) X> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > X Sound Hardware X > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXYes, audio on Linux is a mess. -- Ignacio Vazquez-Abrams <ivazqueznet at gmail.com> PLEASE don't CC me; I'm already subscribed -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part URL: <http://lists.centos.org/pipermail/centos/attachments/20080311/215b1794/attachment-0002.sig>
Ignacio Vazquez-Abrams wrote:> > On Tue, 2008-03-11 at 11:59 -0400, Ross S. W. Walker wrote: > > I have been working a while trying to get a big picture of how Linux > > handles sound processing and after much work I have put together this > > little representation of what I have learned. > > > > Please send me any additional comments or components that I may have > > missed. > > Some corrections (PulseAudio contains an ALSA module that can redirect > audio back into PA):ALSA provides an ALSA driver in it's plugins to send audio to a PulseAudio server, so that part is pure ALSA. I mean sure it uses PulseAudio's protocol to send over the network, but as far as ALSA is concerned it's just another ALSA kernel driver for communicating with sound hardare. The PulseAudio server by itself is of course a pure sound server. Having said that, I don't believe that the ALSA driver for PulseAudio counts as yet another interface. AOSS is merely a shim for the builtin OSS Compatibility API to force older OSS apps to use the API properly, because of that I count AOSS as part of the OSS Compatibility API. Also sound servers can and do use third party API products such as GStreamer. Often GStreamer provides those plugins on behalf of the sound server (cause no one else wants to), but the plugin is still part of the sound server and as far as the sound server is concerned it is just sending audio directly to the hardware API. GStreamer/Phonon also have plugins for communicating with sound servers as well as HW APIs such as ALSA or OSS. When diagramming these third party APIs things can ugly pretty darn fast. Thanks for the additional examples, but I still stand by my original diagram. Maybe someone can take each part of the diagram, zoom in on it and show which apps/apis/modules from which project interface between each other and in which direction.> > Linux Sound Architecture > > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > X Linux Sound Applications X > > X X > > X XXXXXXXXXXXXXXXXXXXXXX > > X X Sound Servers X > > X X ESD/aRts/NAS/JACK X > > X X X > > X XXXXXXXXXXXXXXXXXXXXX X > > X X Third-Party APIs X X > > X X GStreamer/Phonon/ X X > > X X xine-lib X X > > X X X X > > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > X X OSS Compat API X > > X ALSA API XXXXXXXXXXXXXXXXXXXXXX > > X X > > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > X Linux Kernel (ALSA driver) X > > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > X Sound Hardware X > > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > Yes, audio on Linux is a mess.This I do agree with though! -Ross ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.