[linux-audio-dev] audio routing (was: Re: LADSPA GUI Issues)

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Subject: [linux-audio-dev] audio routing (was: Re: LADSPA GUI Issues)
From: Kai Vehmanen (kaiv_AT_wakkanet.fi)
Date: Sun Mar 12 2000 - 12:20:17 EST

On Sat, 11 Mar 2000, Alexander König wrote:

> But now for the other thing I wanted to ask: Let's say we have something
> like a LADSPA-OSS-output plugin. How should that behave? My concern is
> on locking /dev/dsp for example. I see 3 ways this could be handled:

Hmm, I'm not so sure whether this is a good idea. As you pointed out,
additional functions are needed to the API. And handling audio devices can
get rather complex. Multichannel cards, synchronization, etc. etc... But
still, this is a really important subject.

I'd really like to use all these sound generation/synthesis apps that are
currently available for Linux. Csound, Quasimodo, terminatorX, aRts,
ST, oolaboola, etc etc ... this list is a long one. But currently it's
really hard to use multiple audio apps at the same. Nearly all apps
just use /dev/dsp as the output target and have disk-streaming as
an option. I'd like to hear your opinions about this. Here're some
possible solutions:

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.

2) Some kind of loopback/capture system. I've done some experimenting
   with ALSA's (<0.5.x) loopback devices, and while it works (I've
   managed to record SoundTracker's output to ecasound, and to use
   ecasound as a FX box), but this is still rather clumsy.

3) Standard UNIX IPC-mechanisms (pipes, sockets, etc). These of course
   work, but are too clumsy for every day use.

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).

5) MuCoS/LADSPA - could someone help me with these... 

---

Of course, if you have a separate machines for software synthesis, sequencing 
and recording, this is not an issue. The above problem arises, when you want to 
do it all on one machine (live recording, software synths,
samplers and sequencers --> multitrack-recording software --> master).

-- 
Kai Vehmanen <kaiv_AT_wakkanet.fi> -------- CS, University of Turku, Finland
 . http://www.wakkanet.fi/ecasound/ - linux multitrack audio processing
 . http://www.wakkanet.fi/sculpscape/ - ambient-idm-rock-... mp3/ra/wav

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