Meta-event 0x21 - what is it??
Laurence Tyler
Can anyone identify Standard Midi File meta-events 0x21 and 0x20 for me?
I have come across these two unrecognised events in many MIDI files
pulled from the net, but nowhere can I find an explanation of what they
are supposed to be! 'mftext' lists the events as follows:
Time=0 Meta event, unrecognized, type=0x21 leng=1
Time=0 Meta event, unrecognized, type=0x20 leng=1
The actual byte stream looks like this:
For 0x21: 00 FF 21 01 00
For 0x20: 00 FF 20 01 00
These meta-events seem to occur - if they are found in the file at all -
at the start of every track except for the first (timing) track. 0x21
seems much more common than 0x20.
Anybody got any clues?
(Yes, I am writing Yet Another Midifile Player.. :-)
Laurence.
--
Laurence Tyler | Email: lg...@york.ac.uk
Systems Administrator/Programmer | Phone: +44-(0)1904-433807 (DDI)
University of York Computing Service | Fax: +44-(0)1904-433740
Heslington, York YO1 5DD, UK | Web: http://www.york.ac.uk/~lgt1
Guenter Nagler
Laurence Tyler wrote:
>
> Can anyone identify Standard Midi File meta-events 0x21 and 0x20 for me?
ff 21 01 vv => prefix port
used to address more sound devices (e.g. soundcards) playing
one song together. Also used to increase number of channels
(each device has its own 16 channels).
Its a logical number (0, 1,...,not the interrupt number)
All commands of this track are sent to device vv (default=00)
ff 20 01 vv => prefix channel (vv=00-0f)
used to assign channel numbers (1-16) to meta events and sysex events
(events that have no channel number in standard midi protocol).
Usually if a sysex depends on a channel then the channel is encoded
anywhere in the channel data. So I think that this event is only
for editing purpose, that when splitting a track by channel the
sysex and meta events are also moved to right part.
see also midi2txt, midi2hex
http://hgiicm.tu-graz.ac.at/Cpub .... midi utilities for PC/UNIX