MIDI processing question
MIDI processing question
- Subject: MIDI processing question
- From: Kent Clelland <email@hidden>
- Date: Thu, 1 Apr 2004 13:46:54 +0200
hi doug & bill and everyone else.
I' m experiencing some unexpected behaviour in MIDI processing and
before I go coding myself in circles I want to check and see if my
expectations aren't maybe a little bit too high ; -)
here is what is happening:
I enable MIDI input to my application like this:
::
MIDIInputPortCreate(mClient,CFSTR("Output"),ReadProc,(void*)this,&mInPor
t[inIndex]);
and when I receive MIDIPacketLists in my ReadProc() I am _expecting_
that they are sorted in timestamp - ascending order. although I have
not been able to find any solid documentation for or against this, I am
simply expecting that a modern operating system driver will naturally
place the packets in the list as they arrive and how can a later packet
arrive before an earlier one anyway? (huhuh)
HOWEVER, what I am _experiencing_ is that I am in fact recieving events
in the MIDIPacketList sometimes in ascending order and sometimes in
descending, and I *guess* I will someday maybe get some in an arbitrary
order.
so my question is the following: is it wrong for the application
programmer to expect the osX midi system to deliver sorted packet
lists?
[ or one could formulate it this way ]
is it a mistake that MIDIPacketLists are being delivered with arbitrary
timestamp sorting?
[ in which case : ]
whose mistake is it? the USB driver's author?
http://www.motu.com/downloads/MTPMac/usbx_1.22.hqx
or what???
in fact it seems a little silly that if in 90% of the time packets are
being recieved in a given timestamp ordering, to then insert
application code in the MIDI ReadProc() to (RE)Sort the list because
90% of the time this code will only be overhead. PLUS the method with
which these packets are delivered is not the most conducive to
sorting... walking the list with MIDIPacketNext()..
some colleagues are of the opinion that because this seems to only
happen with one particular driver (at the moment) that the driver
"sucks" and there's not alot we can do about it. *HOWEVER* I
personally am of the opinion that since the documentation is not 100%
comprehensive it is a better idea to field the issue here in this
forum, because maybe on the other side of the sargasso they are saying
that those music apps "suck" because they don't sort their incoming
MIDI ... documentation interpretations can lead to such pithy
situations... soooo---> am I missing some documentation? maybe I'm
looking in the wrong place?!
so this all boils down to this multiple choice question:
1) it is the MIDI driver's responsibility to deliver MIDI packets in
the correct order.
[ OR ]
2) it is the application developer's responsibility to (re)sort all
recieved MIDI packets.
Thanks in advance!!!
best from berlin.
|K<
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