Re: Kernel OSS vs ALSA

Bill Huey (billh@burn.ucsd.edu)
Thu, 14 Oct 1999 12:28:40 -0700 (PDT)


> If you're allowing applications to play audio data, then unless you
> have a very cunning mixer daemon, you're trusting them not to drown
> each other out with white noise. In which case, why not map the
> soundcard's DMA buffer into the address space of each application
> that's using the card, and let each application do its own mixing?

And maybe the resister set too and map some library to fully utilize
the DSP chip in these modern cards.

The current ALSA and /dev/dsp conventions can't really respect the
complexity of 3D psychoacoustics modeling through DSP trickery in it's
current form. That might have changed, since I haven't seen ALSA in
about a month or so.

Just reading the EAX SDK stuff make that pretty clear.

bill

> (i.e. the app gets told what volume it's meant to be playing at, scales
> its output accordingly, and just adds each sample to the current
> contents of the next slot in the buffer. On an SMP machine this
> obviously has some drawbacks, but on a UP machine it can work well.
>
> See http://www.cl.cam.ac.uk/~dr10009/audio/ for an implementation of
> this technique.

> Paul

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