Subject: Re: [linux-audio-dev] audio routing (was: Re: LADSPA GUI Issues)
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Sun Mar 12 2000 - 13:29:25 EST
>1) A new audio I/O API that is similar to ALSA's sequencer API.
> Apps would register input and output ports, and the daemon
> side would take care of routing and handling connections.
This is the much-debated "replacement for esd". Some heat and not much
light was generated over on alsa-devel last week about this.
>3) Standard UNIX IPC-mechanisms (pipes, sockets, etc). These of course
> work, but are too clumsy for every day use.
Actually, the two IPC mechanisms you list *don't* work. A Unix pipe is
5K long. For decent sampling rates, it doesn't hold enough data to
handle a couple of context switches between the processes at each
end. A unix domain socket is also a pipe, same limitation, and an IP
domain socket, well it might work, but as you said later, you were
interested in the case where everything was on the same machine.
>4) MIDI-sequencer controls everything (all audio apps MIDI-controllable).
> I don't see this happening (with Linux audio apps.. Windows/Mac world
> is a different thing).
I try to do this for most of my apps. I am just starting to add MIDI
Machine control to libmidi++ in preparation for using it with ardour.
>do it all on one machine (live recording, software synths,
>samplers and sequencers --> multitrack-recording software --> master).
if any more than one of the above has to run SCHED_FIFO, i expect that
concurrent execution of them will not work unless you are operating
with long latencies (large buffers). you need about 100msec of
buffering to record+playback 24 tracks of audio from the hammerfall
without SCHED_FIFO; if you go smaller than that, a regular thread will
create clicks and pops (and thats on a dual PII-450!)
roll on the 4 way athlons :)
--p
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