In-kernel audio mixing ahead
NetBSD's sound device is currently only available for exclusive use.
If one program uses it, another cannot. So if you want to play
some music (mp3, audio stream) that's fine, but if you want
to also have your web browser or mail client make some noise,
this is not possible. Until now.
The solution is to mix
multiple audio sources together, in effect allowing
/dev/sound (etc.) access to be non-exclusive for a
single process but several ones instead.
To make this happen, audio from those sources needs to be
mixed to come out of the same speaker, and since data
writte to /dev/sound gets inside the kernel, that is
a good place to do the mixing.
Challenges in the play are if audio sources are of different
quality (bitrate, stereo/mono, bitrate), so some adjusting
may be needed. All this is met by
the latest patch by Nathanial Sloss,
his posting to tech-kern
for more information.
Also, note his request for review and testing! :-)
[Tags: audio, mixer, sound]