Re: MTP/AV / Sequencer MIDI problem... design issue?

[Ryan Pavlik <rpav@nwlink.com>]

On Sat, 11 Jan 2003 18:31:51 -0500
Paul Davis <paul@linuxaudiosystems.com> wrote:

<snip>
> not really. the mtpav is a "non-standard" device that uses special
> values in the datastream to switch its output port. the ALSA sequencer
> can't know this, and so it can't have any idea that strange things are
> happening at the hardware level.

That's what drivers are for. ;)  The ALSA sequencer shouldn't have to
know of course, but the driver should be able to handle it, and the
architecture should allow a working driver.

Nothing is "standard", anyway... I would contend that if the system
has to consider something "nonstandard" and treat is specially, when
it's just like any other device (pick a midi device at random), then the
system is wrong.

I do not believe, however, ALSA is this way.

> another example of this that i know a bit more about is on the
> tropez+. this has two MIDI output ports, and you can switch between
> them with 2 "unused" MIDI bytes. what should ALSA do if you deliver
> those bytes in a data stream? how can it know what they will do? why
> should it pay any attention at all to them?

It should pay attention because it's a universal sound architecture that
provides software from low-level driver to API.  The low-level driver
is all that needs to know about this.  The higher-level interface
probably does not.

I'm sure all this has been discussed before---I see evidence of it in
the very design and generalization of ALSA itself.  I can't imagine this
design is by accident.

-- 
Ryan Pavlik <rpav@users.sf.net>

"DEPLOY THE ROCKET BOAT!"


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