[openbeos-midi] Re: MIDI parser source (bytestream->MIDImessages)
- From: Christian Packmann <Christian.Packmann@xxxxxx>
- To: openbeos-midi@xxxxxxxxxxxxx
- Date: Wed, 28 Jan 2004 00:13:28 +0100
Matthijs Hollemans wrote:
> > any hints where I can find source code which takes a raw byte stream
> > and parses it into MIDI messages?
>
> The midi_server does something like that already. The code is in
> PortDrivers.cpp. It appears to work on at least some systems, but it is
> not finished yet. The code to split the raw bytes into MIDI message is
> actually pretty simple:
> http://cvs.sourceforge.net/viewcvs.py/open-beos/current/src/servers/midi/PortDrivers.cpp
Thanks! That will help alot - having the switch() and case statements
written out saves a lot of typing. :)
But I think there's a bug, or rather a missing workaround, in the code.
IIRC, some MIDI units don't send proper End-Of-SysEx messages (e.g. Yamaha
DX7), and might simply send normal channel messages after a SYX-dump. So
the code should sense that the SYX-dump is complete after reading any byte
with 0x80 set - SysEx data bytes are always only 7 bit.
> There is also supposed to be a midi_parser kernel module, but this is
> only intended to be used by device drivers. I don't know how it works, or
> whether we already have it in the OpenBeOS CVS.
Didn't find it, but I only had time for a quick look. Anybody knows where
it is (supposed to be) located? I currently don't have time to dig through
the CVS tree...
>> [...] there already is serial_midi, but it only does MIDI-Out, not
>> MIDI-In, and this isn't acceptable.
>
> Hmm, I didn't know that.
I found out the hard way. With a self-made cable, which I resoldered n
times. Desperation. Then I tried out a CBX driver under Windows, which gave
me MIDI-In on the first try... <sob>
> You could always write a replacement driver for
> serial_midi, of course :-) Then the midi_server will take care of parsing
> the raw byte stream.
Hmm, later maybe. AFAIK OBOS will get a new driver system anyway, so it
might be better to wait 'til then. And I don't have any experience with
writing kernel drivers yet, and am still a bit respectful of that...
Bye,
Chris
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