[sdiy] Anyone know of a device that does no-added-delay MIDI filtering?

[ASSI]

On Samstag, 4. März 2006 19:33, Colin f wrote:
> If the filtering device is receiving broken messages, the devices on
> the other side would have received bad messages anyway.

It is still better to filter out (or correct, if possible) such errors.

> Why triple the latency at all times just to be able to recover from a
> situation that would never occur if you have good MIDI output and
> input circuits and a decent cable ?

The way I read the MIDI spec the status byte (sometimes called opcode) 
is not really part of the message. At least that way running status 
makes much more sense to me... anyway, when I was talking about the 
MIDI message, I was assuming that status was already taken care of.

> There are even cases where you might get a broken message it would
> still be better to pass on.

Do some error handling, yes; pass on the error, no. But that's just me.

> For example, if you receive a note on message intact such as 90 30
> 7F, then a note off message 80 30 ... with the last byte missing.
> If you drop that message, you'll get a hung note.

In that case you'd notice no earlier then when the next status byte 
comes along (there is no requirement that I can find to send the two 
bytes of that message in a limited timeframe), and then you can fix the 
message wih some arbitrary velocity value or send an All Notes Off (as 
you can't really be sure how much and what did you miss in the 
meantime).

> If you pass it on, most likely a responding synth will be ignoring
> note-off velocity anyway, and the note will end as you wanted.

I'd say this synth would have a broken MIDI implementation (not that 
this would be unheard of). For a two-byte message, the time to release 
the note is when you receive the second byte of the message, not the 
first.


Achim.
-- 
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Waldorf MIDI Implementation & additional documentation:
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