Subject: Re: [linux-audio-dev] [ardour] custom graphics + MIDI control for LADSPA plugins
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Thu Nov 23 2000 - 17:37:35 EET
>I've thought of using the ALSA API directly at least for figuring out
>HW capabilities. But on the other hand, this makes the virtual
>studio model completely dependen t of ALSA without having a way to
>easily exchange the audio backend API (ALSA in this case).
two comments:
1) at some point, you have to *commit*. despite all my criticism
of some of the bumps in the road of ALSA development, i really
don't have any problem committing to ALSA. if all you want
is a simplistic, naive audio API, then OSS will work for you,
and ALSA will support that. but if you want more, why not
commit to ALSA ? you can waste a lot of time endlessly
building meta-API's to handle the theoretical day when
ALSA is replaced.
2) in my experience of writing linux audio s/w, the abstractions
required by a lot of audio apps can be embodied very easily
in a simple API. ardour's ALSA::MultiChannelDevice is an
example of one such API - its not perfect or comprehensive,
but it for low latency mmap-using applications, its pretty
good. It would not be hard to make a more generic one that
could satisfy almost all applications. This doesn't mean, BTW,
that I think that ALSA is overly complex - it contains
capabilities that a few programs need some of the time,
and thats great. And in fact, the basic ALSA API "template":
snd_pcm_{open,params,prepare,[read,write....],close}
is also very simple.
A notable exception is when dealing with odd audio formats, and
facing the whole question of whether to convert them first or
relying on the h/w or device driver to take care of it. I
believe that ALSA (alsa-lib) 0.6.0's "plugin" model combined
with the new 0.6.0 config files can solve this problem very
easily without creating more application complexity.
>That way the virtual studio API could even run under OSS,
>(and any other audio API)
As detailed by me the other day, "the virtual studio API" cannot use
OSS with pro audio cards. Why waste time on this ?
--p
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