Michael
08-28-2003, 11:18 PM
Hi,
I'm working on a midi sequencer, and am trying to determine the best way to
handle time signature messages in a midi file. In particular, how to
interpret the "bb" param of the time sig meta-event, as described in the
midi spec. This is the param that defines "the number of notated 32nd notes
in what MIDI thinks of as a quarter note (24 MIDI Clocks)".
I've been testing the behavior of Cakewalk Sonar (2.1), Pro Tools Free for
Windows and Emagic Logic 5.5 on OS 9. Cakewalk and Logic always seem to
disregard the "bb" paramter of the time signature. I've tested with time
signature of 4/4, 6/8 and 4/16 with different values for the "bb" param, but
they always play back with the tempo relative to a musical quarter note.
Technically, if I define, for example, the "bb" param as 4, the tempo should
be relative to an 1/8 note and not a 1/4 note. In Pro Tools, the files all
open up with the quarter note taking the beat for tempo's sake no matter
what the time signature "bb" value, but it can be manually overridden. In
addition, the midi clock output is always relative to a musical quarter note
as well, ie 24 clocks. In Pro Tools, if I change the note value that takes
the tempo, the clock count is _still_ 24 / musical quarter note, which then
makes things goofy, I think.
So is this some sort of de facto standard way of treating tempo of midi
files? ie to ignore the "bb" param?
Also, less importantly, Cakewalk and Logic ignore the "cc" param of the time
sig which defines the number of midi clocks per metrenome click, whereas Pro
Tools Free seems to honor it, albeit with one exception I find which is
possibly a bug.
Does anyone have experience with this, or maybe know of a detailed
discussion I could reference?
Many thanks,
Michael
I'm working on a midi sequencer, and am trying to determine the best way to
handle time signature messages in a midi file. In particular, how to
interpret the "bb" param of the time sig meta-event, as described in the
midi spec. This is the param that defines "the number of notated 32nd notes
in what MIDI thinks of as a quarter note (24 MIDI Clocks)".
I've been testing the behavior of Cakewalk Sonar (2.1), Pro Tools Free for
Windows and Emagic Logic 5.5 on OS 9. Cakewalk and Logic always seem to
disregard the "bb" paramter of the time signature. I've tested with time
signature of 4/4, 6/8 and 4/16 with different values for the "bb" param, but
they always play back with the tempo relative to a musical quarter note.
Technically, if I define, for example, the "bb" param as 4, the tempo should
be relative to an 1/8 note and not a 1/4 note. In Pro Tools, the files all
open up with the quarter note taking the beat for tempo's sake no matter
what the time signature "bb" value, but it can be manually overridden. In
addition, the midi clock output is always relative to a musical quarter note
as well, ie 24 clocks. In Pro Tools, if I change the note value that takes
the tempo, the clock count is _still_ 24 / musical quarter note, which then
makes things goofy, I think.
So is this some sort of de facto standard way of treating tempo of midi
files? ie to ignore the "bb" param?
Also, less importantly, Cakewalk and Logic ignore the "cc" param of the time
sig which defines the number of midi clocks per metrenome click, whereas Pro
Tools Free seems to honor it, albeit with one exception I find which is
possibly a bug.
Does anyone have experience with this, or maybe know of a detailed
discussion I could reference?
Many thanks,
Michael