From alsa-user-owner@alsa.jcu.cz  Mon Apr 27 23:09:54 1998
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From: Frank van de Pol <F.K.W.van.de.Pol@inter.nl.net>
Message-Id: <199804272040.WAA32291@obelix.fvdpol.inter.nl.net>
Subject: Re: gus modplayer (take #2)
To: alsa-devel@jcu.cz
Date: Mon, 27 Apr 1998 22:40:54 +0200 (MET DST)
Cc: alsa-user@jcu.cz
In-Reply-To: <Pine.LNX.3.96.980424092107.6191B-100000@entry.jcu.cz> from "Jaroslav Kysela" at Apr 24, 98 10:10:46 am
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Jaroslav Kysela wrote:
> 
> On Fri, 24 Apr 1998, Smoke of Crap wrote:
> 
> > whether a buffer that starts after 0.25 seconds is usable.. For a tracker 
> > for example one wants to play music on the keyboard.. Well it might be 
> 
> This is problem... There is some delay for system delivers MIDI data to
> application and next delay can be caused by application which should 
> compute and write new data for digital audio stream...
> 
> I'm planning emulate MIDI THRU in driver which passes MIDI data from some
> input interface (for example) to internal syntesizer in interrupt routine.
> Delay should be minimal in this case. Maybe something should be done for
> programmed syntesizer interface (for modplayers/trackers) and tracker
> should only record (with some buffering) input events. This can't be done
> for digital audio stream (PCM) of course (even driver should support
> software mixing, but there will be delay in all cases)..

I don't think this approach to do MIDI THRU is good enough. If you simply
copy the MIDI bytes from one device to another, one might not get the events
to the channel the events should go to.

To overcome this, the MIDI THRU driver will have to do some channel
remapping, perhaps some MIDI filtering, some merging, and will at the end
not be that simple anymore (from application's point of view).

I'll post a proposal to get us a framework that overcomes these problems.

Regards,
Frank.

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