[sdiy] MIDI running status implementation - status bytes

[Tom Wiltshire]

Thanks all.

I've never found System Realtime to be a problem. Its behaviour suggests to me that it was intended to be stripped out in the MIDI Rx interrupt and dealt with directly. So that's what I've always done. If it's a System Realtime byte, I either deal with it or ignore it. Anything else goes into the MIDI message buffer. That way, the buffer is clear of System Realtime and (for example) I don't have to worry about random MIDI clock bytes in the middle of my Note On message.

Tom


On 1 Feb 2014, at 08:44, Ullrich Peter <Peter.Ullrich at kapsch.net> wrote:

> And don't forget that the System Realtime bytes can happen EVERY TIME!
> So also between status and data bytes...
> 
> So even if your software doesn't need the System realtime messages you have to 
> completely ignore them otherwise your MIDI decoding could get in trouble.
> So just throw them away without putting them in a buffer or further processing if not needed.
> 
> I had this proble with my very old Korg MS10 MIDI to CV converter lotsa years ago...
> 
> Ciao
> Peter
> 
> http://www.ullrich.at.tt
> 
> ________________________________________
> Von: synth-diy-bounces at dropmix.xs4all.nl [synth-diy-bounces at dropmix.xs4all.nl]" im Auftrag von "rsdio at sounds.wa.com [rsdio at sounds.wa.com]
> Gesendet: Samstag, 01. Februar 2014 09:06
> An: Neil Johnson
> Cc: synth-diy
> Betreff: Re: [sdiy] MIDI running status implementation - status bytes
> 
> and don't forget that System Real-Time is the exception to the rule.
> Although System Real-Time messages are technically Status Bytes, they
> do not interrupt Running Status. This is possible only because System
> Real-Time messages are only one byte in length, so they will never
> confuse the multi-byte state machine in your MIDI parser.
> 
> Brian Willoughby
> Sound Consulting
> 
> 
> On Jan 31, 2014, at 07:03, Neil Johnson wrote:
>> Andre,
>> 
>>> Tom, your question and Neil's replies leave me slightly
>>> confused.
>>> 
>>> Why do you say "in the case of channel status bytes" ? Running
>>> status only applies to channel status bytes.
>> 
>> While Running Status only _applies_ to channel status messages, it is
>> _terminated_ by _any_ status byte.
>> Of course, if the exact same status byte is received it is as if
>> Running Status was in effect. And if another channel status byte
>> arrives then a new running status starts.
>> 
>> Neil
> 
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