Re: [Jack-Devel] Dispersing MIDI messages: one to multiple

@Christian Schoenebeck wrote:
- Good point about JACK MIDI input implementation, etc.

Yes, exactly.
I'll add the following re Hardware MIDI / software MIDI, just for
completeness and future reference.

On Sat, Jan 31, 2015 at 6:16 AM, Happy <[hidden]> wrote:
> For whatever it is worth, many older devices any even modern devices
> (For example I can guarantee it for the Roland TR-8, released in 2014)
> still apply running status on their MIDI outs.
Yes indeed: and it makes sense for *hardware* MIDI units to do so. The
MIDI cable[1] runs at a baud rate of 31250, which limits the amount of
messages that can be sent over the cable in a certain time-period.
Using running-status increases the amount of events that can be sent.

On the software side, having running status is a bad idea: the 4 bytes
duplicated to have a status per message is well worth spending, if
consideration is given to ease of implementation of MIDI code.

So in a best-of-both-worlds, hardware uses running status (as the
hardware you mention does), and software always includes the status
byte, so implementations check the first byte of the message and
easily deal with it.

As Christian noted, this is exactly what JACK does - MIDI input
drivers add the running status byte to messages that did not include a
status byte, and provides the JACK MIDI graph (and hence all JACK
clients) with normalized "status byte included" MIDI messages.

Cheers, -Harry

[1] Note that an actual 5 pin DIN MIDI cable is meant: USB MIDI
generally runs at 115200 baud, allowing many more events per unit
time.

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