[LAD] [64studio-users] MIDI jitter

[fons at kokkinizita.net]

On Wed, Jun 30, 2010 at 02:27:09PM +0200, Adrian Knoth wrote:

> Let me just show you the result from my Midisport USB 2x2 (standard
> edition when it was still produced by midiman, not the anniversary
> edition):
> 
> set_realtime_priority(SCHED_FIFO, 20).. done.
> clock resolution: 0.000000001 s
> 
> > latency distribution:
> ...
>   3.1 -  3.2 ms:        1 #
> ...
>   3.9 -  4.0 ms:        1 #
>   4.0 -  4.1 ms:     9903 ##################################################
> ...
>   5.0 -  5.1 ms:       95 #
> 
> > SUCCESS
> 
>  best latency was 3.13 ms
>  worst latency was 5.00 ms, which is great.

I've no idea how this test works, but if it uses the same
interface for TX an RX the results should be treated with
a healthy dose of scepticism. 

To be really reliable, the transmitter and receiver should
be on different machines. Measuring absolute latency can
be difficult in the case (but not impossible) but jitter
is easy.

Ciao,

-- 
FA

O tu, che porte, correndo si ?
E guerra e morte !