Re: user mode sequencer timer?

[Takashi Iwai <tiwai@suse.de>]

At Mon, 19 Aug 2002 17:42:07 +0200 (CEST),
Tim Goetze wrote:
> 
> Takashi Iwai wrote:
> 
> >At Mon, 19 Aug 2002 09:22:10 +0200 (CEST),
> >Tim Goetze wrote:
> >> 
> >> Is it possible to register a sequencer client that acts as a timer
> >> (not only an event consumer/producer), and if so, how would one go 
> >> about implementing one?
> >
> >timer = event producer in a certain schedule, isn't it ??
> >it will deliver "tick" events in a programmed rythm.
> 
> You mean it is sufficient to emit SND_SEQ_EVENT_SETPOS_TICK or *_TIME 
> periodically, and transport control events accordingly? Are these 
> events then used by alsa-lib to update the queue timing information?

well, sorry, then i misunderstood your question.

do you mean that a sequencer client as a timer source, or as a
controller of the queue?

the former is difficult, because the queue is driven by interrupts
from a timer source.  that is, a sequencer client must give signals at
the constant and fine period.  this is not a job what a user process
does.

the latter, controlling a queue, would be feasible.
in this case, you can change the tempo or time skew dynamically by
sending events via system-timer port (0:0) to a specified queue.
but anyway, a queue must run individually from the client.

maybe i can give more specific answer if i understand your question
more clearly...


ciao,

Takashi


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