[linux-audio-user] Keyboardist jitter detection?

[Alexandre Ratchov]

On Sat, Feb 10, 2007 at 02:52:28PM +0100, Mario Lang wrote:
> Hi.
> 
> I recently started to play a little keyboard.  After guitar
> and traverse flute, the keyboard seemed the logical next step.
> 
> I guess its totally normal to have a little problem with
> exactness.  I wonder if there is a MIDI tool that
> could be used to measure my average jitter so that I could
> test myself and see if I improve?
> 
> For instance, when playing BWV 846, it should be actually
> fairly easy measurable since that piece consists of mostly
> only 16th notes.
> 
> Does such a program exist?  I know the concept isn't that
> strange, Stanley Jordan told in a master session he
> was doing something like this with his MIDI-fitted guitar.
> 

hi,

recent development snapshots (not releases) of midish display the
average jitter when a track is quantized. This isn't really a
feature, it's here mainly for debugging purposes. Once MIDI devices
are setup, you can use it as follows:

$ rmidish
send EOF character (control-D) to quit
1> nt mytrack			# create a new track
2> r				# record with metronome
press control-C to finish
^C
--interrupt--

3> sel 100			# select 100 first measures
4> n 16				# set quantization step to 16th note
5> q 100			# quantize the selection
track_quantize: fluct = 109, notes = 155, avg = 70% of a tick
6> 

so the average jitter is 70% of a MIDI tick (there are 24 ticks in
a quarter note). Above commands could be embedded in a shell
script. Feel free to contact me if you encounter problems.

cheers,

-- Alexandre