1 Apr
2009
1 Apr
'09
6:10 p.m.
On Wednesday 01 April 2009 at 19:46:30 Clemens Ladisch wrote:
It is a part of the MIDI protocol.
Sorry, I do not get it.
I have checked the ports using aseqdump connecting to the two UM2 ports of the
external USB MIDI interface.
aseqdump did not report any error message, so I think I can assume that at
this connection there is no problem running status vs. normal status.
I connected the two UM2 ports to the MIDI Thru port and checked to see if
merging works, got no error messages from aseqdump either. I checked this
both UM2 connectors at a time, then both merged into one output.
I am also not sure if I got the USB MIDI part correctly: what I have is an
external USB device that offers two IN/OUT ports having standard 5 pin DIN
connectors each to connect to other standard MIDI devices. So this device is
not transferring USB MIDI data - it is imho simply converting ordinary MIDI
data into USB data without further manipulation, then inside the notebook
ALSA applications see the UM2 connectors as a standard MIDI hardware port
each.
So the hardware ports that I see denoted as UM2 have got to be ALSA sequencer
ports.
I have never had any issues related to running status vs. normal status before
until I wanted to use keykit to work on incoming MIDI data. This is where I
cannot find what causes the error.
I suspect it is keykit that needs more than one IN port and it is keykit which
cannot merge two different MIDI streams that come in at its IN port - but I
am not yet 101% sure about that. So in contrast to what is normally possible
(connect more than one OUT port to one IN port) keykit cannot do this.
Kind regards,
Crypto.
Justin Smith wrote:
> On Wed, Apr 1, 2009 at 3:32 AM, Clemens Ladisch <cladisch(a)fastmail.net>
wrote:
Please note that neither the USB MIDI protocol nor
ALSA's sequencer
messages can use running status.
If I understand correctly, running status is not an alternative to the
MIDI protocol, it is an alternative way of interpreting the
bytes (comparable to
nrpn or such), so there should be no issue of MIDI or ALSA
incompatibility.
Running status is a feature of the encoding used by MIDI.
USB MIDI and the ALSA sequencer use different encodings.
A USB MIDI adapter converts from MIDI to the USB MIDI protocol, and the
USB MIDI driver converts that data back to MIDI. It is not possible to
detect from the result whether the original MIDI data used running
status.