Re: I/O Latency (Was: Layman with a mission)
Re: I/O Latency (Was: Layman with a mission)
- Subject: Re: I/O Latency (Was: Layman with a mission)
- From: "Angus F. Hewlett" <email@hidden>
- Date: Wed, 13 Oct 2004 12:50:51 +0100
Dennis Gunn wrote:
OS 9 Macs are General Purpose computers and running RME hardware they
can apparently accomplish that buffering in 6 samples each direction
for a total of 12 samples when a DAW application is run on them.
Sorry, but an OS 9 Mac is in many ways not really a general purpose
computer in the modern sense. I know that sounds kind of crazy from an
end-user perspective, but from a technical point of view it really is
the case.
It may be true that OS9 has lower latency,
It is true and is very well known.
Yes, when used in certain specific ways, which treat the computer more
like a piece of dedicated hardware and not as a general purpose desktop
machine. These techniques also force application and plug-in software
engineers to think like driver programmers or embedded systems
programmers, and that ain't a good thing either.
Excuse me I did not mean to say that I thought that the safety buffer
could be *eliminated* just reduced to something like what it was in OS9.
Unfortunately, it just isn't possible. Stability & flexibility vs
latency vs overall system efficiency is always a tradeoff - if you like,
OS X puts cast iron "safety rails" between applications, hardware and
the system itself (as do Unix and WinXP; OS9, being an '80s throwback,
does not), and policing and maintaining those rails requires some system
time. There is no sane way of turning those rails off, and most software
developers and other technology professionals see that as a Very Good
Thing. It does, however, cost something in minimum system latency, and
nobody is denying that.
Once again I am talking about the function of core audio to conduit
the audio stream between an audio sequencer and Audio hardware and the
safety offset buffer that it seems to need to accomplish that end. In
OS9 it was MUCH smaller and that is a documented fact that is very
well known in the audio community.
Indeed. However, to understand why CoreAudio works the way that it does,
and why the extra buffering is needed, requires some understanding of
the truly V-A-S-T architectural differences between OS 9 and OS X.
Best regards,
Angus.
--
=========================================================
Angus F. Hewlett, Managing Director (CEO)
FXpansion Audio UK Ltd - http://www.fxpansion.com
Registered in the UK - #4455834 - VAT: GB 798 7782 33
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