timing accuracy of a Yamaha keyboard's MIDI sequencer

Hi there--

I've written some simple Perl scripts that can analyze midi Note On data to see how closely they match an input template over, say, 8 beats. The idea is to study my timing / consistency as a keyobard player, and see if I can tighten up my timing. Say I'm trying to play straight quarter notes. I will create a template of quarter notes over a single measure. My scirpts will take a MIDI file as input, fit each Note On data to the nearest quarter note, and continue over all the measures until I end up with 4 distributions, one for each quarter note. At each distribution, I can see the average and std-dev of the timing of the hits for that quarter note in milliseconds.

Right now, when I play a montuno figure, my stddev in the hits is about 10ms: that is, from measure to measure, I vary my placement of each hit about 10 ms from the previous one, on average. Ideally, then, I would want my sequencer to have around 1 ms accuracy in how it records each note press, so that I can detect improvemnt in my timing.

My concern is with my Yamaha keyboard's accuracy in recording the MIDI events ( it's a ypg-625 ). I am playing / recording a song file directly onto the keyboard, then transferring this later to my laptop for analysis. When the tempo is around 110bpm, the smallest delta between consecutive note on events is 2 ms---this occurs when I play octaves that are meant to be simluataneous. However, when I dial the tempo down to about 70bpm, that figure jumps to 9 ms. Three questions:

- what's the best way to tell the timing accuracy of my keyboard? I looked up the specs and couldn't find anything.

- is there another keyboard / method that will produce better accuracy?

- is the accuracy bound to the tempo? I remember hearing about midi time clock being tied to something like 480 ticks per beat on a professional sequeencer, which implies that tempo is locked to the accuracy of the ticks.

Thanks

Isaac

Reply to
zikester
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I don't know the answer to your question, but I wonder... what would happen if you didn't use the keyboard to record the file, but connected the midi output to sequencer software on the computer? Then the tempo setting on the synthesizer shouldn't enter in.

--
John
Reply to
John O'Flaherty

zikester wrote: [ ... ]

(Off topic, but it's something I've worked with.) IIRC There's a field in the MIDI file header specifying the number of ticks per quarter note used in that recording. This is commonly a number like

240, sometimes as low as 96. Your MIDI recorder might let you specify a setting, but otherwise it is, as you say, locked in with the tempo.

If you can't specify that setting, you best bet is to run the recorder at the highest available tempo setting purely to get the time resolution; physically play your keyboard at a different tempo that's musically interesting, and look only at the tick times in the recording, ignoring what should or shouldn't be a quarter-note, etc. in the recorded file.

Mel.

Reply to
Mel

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