[comp.music] MIDI FILE answer

bri%midiline@vlsi-mentor.jpl.nasa.gov (brian benison) (04/10/90)

>It is not specified whether event deltas should refer to
>a time interval computed at the time of the previous event and
in
>the current time base, or whether the time interval must account
for
>any tempo changes (and thus delta unit size changes) during the
time span
>preceding the event.

It seems to me that the next event after a tempo-change event
would occur at the time based on the new tempo specified by that
tempo-change event, figured from the delta time of the tempo
change event.

DeltaTime(decimal)   Event                       Data
0                    $FF5103 meta event(tempo A) <microsecs per
quarter>
0                    $903C40 deltaEvent(noteOn)  --
4                    $803C40 deltaEvent(noteOff) --
0                    $FF5103 meta event(tempo B) <microsecs per
quarter>
                                 -- let's say tempo B is 2 *
tempo B --
8                    $903C40 deltaEvent(noteOn)  --
8                    $803C40 deltaEvent(noteOff) --

This example represents a note(middle C), a rest, and another
note, with a tempo change at the end of the 1st note.  The number
of microsecs of each note or rest in this example is the same.
Hope this helps.
Brian Benison, Briter Music