Subject: Re: [linux-audio-dev] Alsa /dev/sequencer stuff
From: Paul Davis (paul_AT_linuxaudiosystems.com)
Date: Tue May 20 2003 - 07:47:41 EEST
>In my app (RTMix) I will be soon implementing multiple midi-input device
>opens, so that the app can be controlled from as many of the midi
>controllers simultaneously as possible. One way of devising this was to
>design a separate thread for every open device (using raw midi /dev/midi
>etc., although I will be re-implementing that to use ALSA devices
>directly).
although i've been a big advocate of using raw midi ports in the past,
i've pretty swung around on this issue. i think you should use the
ALSA sequencer API instead. that way you can connect applications to
each other, rather than just applications to h/w. same thinking as
JACK in this regard.
> However, this might not be the most elegant way of doing
>this, so what I was wondering is how does the /dev/sequencer correspond
>to this issue? I mean, does it work the same way like addressing the raw
>midi ports, are the message formats the same, and most importantly does
>one SINGULAR /dev/sequencer encompass all of the midi ports that are
>currently available?
no, just one port. the OSS sequencer /dev/sequencer is only a
scheduler - it has no routing capabilities at all.
the ALSA sequencer (/dev/snd/seq etc.) is a multiplexer/demultiplexer,
and handles both scheduling and routing, and covers all available h/w
ports and registered s/w clients.
don't leave home without it :)
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