From alsa-devel-owner@alsa.jcu.cz  Thu Jun 25 10:17:19 1998
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Date: Thu, 25 Jun 1998 10:17:24 +0200
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From: Winfried Ritsch <ritsch@iem.mhsg.ac.at>
To: alsa-devel@jcu.cz
Subject: Re: Time resolution needed for sequencer
In-Reply-To: <35917805.4677DF9C@bath.ac.uk>
References: <199806241944.VAA25193@obelix.fvdpol.inter.nl.net>
	<35917805.4677DF9C@bath.ac.uk>
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Paul Leonard writes:
 > Frank van de Pol wrote:
 > > 
 > > Hi,
 > > 
 > > I'm working on a prototype for the ALSA sequencer and would like to know
 > > what timing resolution / what unit for timestamps is needed. Please give
 > > some input on this subject.
 > 
 >  1ms is fine by me. 
 > 

The fact there is MIDI defined as 31.25KB with 10bits per byte,
a byte is ca. 0.3ms and realtime messages (which are the critical
ones) are 1 byte long so the miminum resolution should be 1/31250 =
0.311 ms to be perfect.

since note on offs are 3(2)bytes 1ms are also not so bad, 
(but if you
dont read midibytes at maximum rate from input then there is the
possibility there are some lost if you output them again with wrong
time stamps.)


msg winfried

--- DI Winfried Ritsch - ritsch@iem.mhsg.ac.at ---
 INSTITUT FUER ELEKTRONISCHE MUSIK-
 University of Music and Dramatic Art
 Tel. ++43-316-389-7210, Fax.++43-316-389-7008

 





