[PD] midi latency test

[Chris McCormick]

On Thu, 6 Mar 2003 16:45:20 +0100 (MET)
Johannes Taelman <Johannes.Taelman at rug.ac.be> wrote:

> On Wed, 5 Mar 2003, Greg Rippin wrote:
> 
> > Do MIDI In jacks still use opto-isolator components?  I think they did
> > in the original spec...  The rise- and fall-times could account for the
> > added delay perhaps?
> 
> Not possible.
> 1 bit at midi rate is 1/31250Hz = 32 microseconds
> The rise- and fall-time of this optocoupler should be a fraction of that.
> 
> I also heard the myth more than once that there is a substantial delay
> between midi-in and midi-thru ports. There is a delay from midi-in to
> midi-out or a 'soft' midi-thru, because the midi-commands are parsed
> before thay're retransmitted. A dedicated midi-thru is just a signal
> buffer.

I've built a pc-joystick-port to midi box, and at least in my version the midi thru was directly wired to the midi in, giving almost exactly zero latency (factoring in the movement of electrons through copper wire media).

Chris.
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