Re: alsa userspace interface

["Clemens Ladisch" <cladisch@fastmail.net>]

Andrea Guzzo wrote:
> we are wondering if it's possible to register an alsa device from
> userspace.

It is not possible to register a kernel device from userspace, but it is
possible to write a plugin that is used by the alsa library like a
kernel device.

Have a look into the alsa-plugins package.

> Is there any working or experimental one?

The FreeBoB project is writing an ALSA plugin for some IEEE1394 devices.

> Another interesting use of an hypothetical alsa userspace interface  
> for device drivers implementation would be the possibility to
> implement virtual audio devices ....for example you could implement a
> transparent sound server that doesn't require applications to support  
> it explicitly and to link specific libraries, but it would be simply
> accessed like any other alsa device and, with the use of substreams,
> it would allow multiple applications to access audio facilities....
> but this is another story :P

This story is called dmix.  This plugin has been part of alsa-lib for
years, and it doesn't need a server.  :-)


Regards,
Clemens

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