Running status for DIN

[dlundqvist]

Hi,

Didn't see anything in the User Manual about running status, but if it's clarified in some other place please link to it. I assume that running status on DIN input won't be a problem, but will it create running status on DIN output?

[Jesse Johannesen]

I am not too familiar with running status, but a quick google search indicates it has to do with sending 0 velocity note messages instead of "note offs" as a way to avoid breaking up note on messages? If that's the case it should be totally doable as MRCC in almost every case just pumps out what is input, but just to be sure I will ask Steve to clarify this and report back.

[Royce]

Hi,
Didn't see anything in the User Manual about running status, but if it's clarified in some other place please link to it. I assume that running status on DIN input won't be a problem, but will it create running status on DIN output?

Normal Midi
Mod wheel
Status = CC channel 3 - type =1 - value
CC channel 3 - 1 - 10
CC channel 3 - 1 - 23
CC channel 3 - 1 - 29
CC channel 3 - 1 - 32

3 bytes per message

Midi running status is when the Status byte (Note On, CC, PC etc + channel) is sent and then just a stream of 2 byte data is sent until the status is changed.

On a Midi breath controller like a WX5 you will see a
Note On (channel 3) + key + velocity,
then a status change to
CC (channel 3)  + type 2 (breath control)  + value,
2 + value,
2 + value,
2 + value,
2 + value...

then a status change - say mod wheel (CC 1), but as we are already sending status CC on channel 3 the WX will just send CC type and value...
1 + value,
1 + value,
1 + value,
1 + value,
1 + value,
1 + value...

This way you can reduce the amount of Midi data by not repeatedly sending the status byte.
This is very important for controllers that send lots of data.
Microsoft decided that this was too hard and forced Midi driver developers to convert all running status midi to repeated status form before it was passed to Windows.
This is why you won't see running status inside your PC without a special driver.

[dlundqvist]

I am not too familiar with running status, but a quick google search indicates it has to do with sending 0 velocity note messages instead of "note offs" as a way to avoid breaking up note on messages? If that's the case it should be totally doable as MRCC in almost every case just pumps out what is input, but just to be sure I will ask Steve to clarify this and report back.

Well, that is one use of running status. It just a form of compression for the bytes going over the wire. Here, http://midi.teragonaudio.com/tech/midispec/run.htm, is a good overview of what it is and what the benefit is.

[Jesse Johannesen]

I asked Darryl and he said it shouldn't be any problem. Thanks for the link, I'll go have a look at that.

[oldgearguy]

FWIW, I sent the running status spec to the MRCC guys back in August of 2022

[dlundqvist]

I asked Darryl and he said it shouldn't be any problem. Thanks for the link, I'll go have a look at that.

It's not clear to me, but do you confirm that MRCC will create/use running status when there is a chance to do so on DIN ports?

[oldgearguy]

I don't think the MRCC will take 'long' MIDI messages and create running status versions. I think what Darryl and Jesse are saying is that gear that sends running status is handled properly.

[dlundqvist]

I don't think the MRCC will take 'long' MIDI messages and create running status versions.  I think what Darryl and Jesse are saying is that gear that sends running status is handled properly.

Well, that is exactly what it must/should do when message is from USB since the concept of running status does not exist there.

[oldgearguy]

I don't think the MRCC will take 'long' MIDI messages and create running status versions.  I think what Darryl and Jesse are saying is that gear that sends running status is handled properly.

Well, that is exactly what it must/should do when message is from USB since the concept of running status does not exist there.

Again,  it's up to the sending thing (hw, sw) to generate running status, not up to any middleman since they have no idea what msg is coming next. 

USB in and of itself does not dictate whether running status is allowed.  The MIDI protocol defines the messaging.  USB is really just a transport mechanism.