Subject: Re: [linux-audio-dev] an open letter to Linus re: low latency
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Fri Jun 23 2000 - 05:34:40 EEST
>> I wonder if UCB would have any interest in developing an advanced audio
>> subsystem, in the same manner that MIT developed X Window?
With all due respect to those thinking along such lines, I think this
is simultaneously premature and too late.
At the driver level, ASIO is emerging as an excellent de-facto
standard from the Windows and MacOS world, and it has very clear
parallels in ALSA (to the extent that I think ALSA could support an
ASIO API). Any attempt to "redefine" these API's will be met with
fairly stiff resistance from the involved parties.
In user-space, there is a need for a multi-app-accessible interface
(like esd), as well as networked audio services.
However, I think that X has shown us the way here: it turns out that
as useful as the networking stuff is, there are a whole class of
things that really work much better when they have "direct" access to
the underlying device drivers, and in some cases will not work without
it. X does try to hide this, but sometimes at a cost (though to be
fair, recents tests of DRI-based XFree86 4.0 drivers for various video
cards showed them to often be remarkably close to the fastest, newest
Windows drivers, despite supporting the full multi-app, multi-user,
networked model that X does).
This distinction between "close to the h/w" and "i want my API" is
even more true for audio. There is no way in hell that you would
sensibly do real-time FX on a networked audio connection. For such
things, you want to sit nice and close to the audio interface. But for
many things (WM audio messages, for example), you really want a nice
API that handles networking transparently.
As a result of this distinction we should not expect a single uniform
"audio subsystem" that all audio apps could use. The same thing is now
happening with X, with the emergence of DRI and Berlin, except that
its happening after X's widespread adoption.
In closing, I would note that the acronym ALSA stands for "Advanced
Linux Sound Architecture", and that the ALSA project has been
approached by other companies thinking of using ALSA as the API for
their own sound systems.
--p
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