New subject: [Bug 33126] divided SysEx and coalesced midiOutLongMsg

5 Mar 2013


      http://bugs.winehq.org/show_bug.cgi?id=33126
Bug #: 33126
           Summary: divided SysEx and coalesced midiOutLongMsg
           Product: Wine
           Version: 1.5.25
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: winealsa.drv
        AssignedTo: wine-bugs@winehq.org
        ReportedBy: hoehle@users.sourceforge.net
    Classification: Unclassified
Johannes Kroll reported in wine-patches that the KORG Kontrol Editor software
hung after sending an ill-formed SysEx via winealsa's midiOutLongMsg.
http://www.winehq.org/pipermail/wine-patches/2013-January/121335.html
The MIDIHDR data is F0 ... F7 00 00 00 (125 bytes).
http://www.winehq.org/pipermail/wine-devel/2013-February/098852.html
He observed that no hang occurs when skipping the trailing 3 zero bytes.  F7 is
the "End Of SysEx" (EOX) marker.
It is still unclear what happens.  MIDI HW is expected to skip over bogus
bytes, thus the zero bytes should cause no harm.  OTOH, ALSA might be getting
into trouble processing ill-formed messages, and we don't know if or how many
bytes ALSA actually sent out through the serial port.
In any case, midiOutLongMsg handling in Wine needs fixes.
- winealsa should extract the F0...F7 part and send that as a SysEx.
- More generally, midiOutLong is known to accept not only SysEx packets, but
also coalesced status messages.  Some MIDI authors prefer to send e.g. chords
via one LongMsg rather than successive calls to midiOutShortMsg, arguing that
it's faster.  Hence all Wine MIDI drivers need to decompose midiOutLongMsg into
packets consisting of status message, regular SysEx ... and possibly junk.
- All APIs (MS, ALSA, OSS, CA) acknowledge the existence of divided SysEx.  As
a result, framing SysEx with F0 ... F7 is entirely under application control. 
The current winealsa framing code is simply wrong.
- winecoreaudio always declared 3 bytes for short messages, even program
change.
I have written a sequence of patches to fix all of this.  The only thing that
is unclear is how to encapsulate garbage data like the above 3 zero bytes or
real time messages with ALSA.  What ALSA API function and what ALSA message
type to use?  Heck, I'm not even sure winealsa.drv/midi.c:modData is ok to send
a 2-byte MTC quarter frame via snd_seq_ev_set_sysex instead of using a
primitive that sets the type SND_SEQ_EVENT_CLOCK/TICK.
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[Bug 33126] New: divided SysEx and coalesced midiOutLongMsg