Re: A Couple of Midi Tempo and TimeSig Questions
Re: A Couple of Midi Tempo and TimeSig Questions
- Subject: Re: A Couple of Midi Tempo and TimeSig Questions
- From: Brian Willoughby <email@hidden>
- Date: Wed, 14 Apr 2004 20:02:43 -0700
Peter,
I believe that the theoretical maximum Tempo would be 60,000,000 BPM. The
Standard MIDI File encodes a Tempo Meta Event in microseconds per quarter-note,
as a 24-bit integer. The lowest Tempo would be 0.27962 BPM. However, the
Tempo is also effectively modified by the Time Signature Meta Event, which
includes a byte for "Clocks Per Metronome Click" [0-255] and "Notated
32nd-notes Per MIDI Quarter-Note" [0-255]. The math for that is left to the
reader. I couldn't find the SMF spec on hand, and I cannot remember if the
usec count is allowed to range from 1 to 16,777,216 as allowed by the bits
allocated.
I realize that these limits are so large as to be of little help. The only
good news is that the Tempo is not unbounded, although the allowed range is
incredibly large compared to the practical user range.
Brian Willoughby
Sound Consulting
Begin forwarded message:
Date: Thu, 15 Apr 2004 10:59:26 +1000
Subject: Re: A Couple of Midi Tempo and TimeSig Questions
From: Peter Zegelin <email@hidden>
To: email@hidden
>
> Also is there any default maximum Tempo value? I'm generating a
>
> fairly standard squiggly line type Tempo view and was wondering what a
>
> reasonable maximum might be. At the moment I am actually calculating
>
> the maximum tempo for the current file and using that, but is there
>
> some sort of standard?
[...]
However my question was more about what would be a reasonable maximum
for display purposes. All the other events that are commonly displayed
(and edited) as a squiggly line (not sure of the correct term here!)
have defined minimum/maximum values - whereas Tempo events don't, and I
was just wondering if there is a commonly used value (say 500).
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