Re: Genetics and Analog to Midi
By Robbie Rhodes
I received a note from Artis Wodehouse inquiring how to analyze a live-recorded phonograph performance for the statistics of the note- and chord-attack timing. She would like to properly "randomize" the timing of a heavily-edited piano roll performance in order to make it sound more like a live performance.
Artis referred me to two recent articles which I'm now reviewing:
[1] J. Berger, R. Coifman and M. Goldberg, "Removing Noise from Music Using Local Trigonometric Bases and Wavelet Packets," J. Audio Eng. Soc., Vol 42, No. 10, pp. 808-818 (October 1994)
[2] J. Berger and C. Nichols, "Bhrams at the Piano: an Analysis of Data from the Brahms Cylinder," Leonardo Music Journal, Vol. 4, pp. 23-30 (1994)
Author Jonathan Berger is a composer and music professor and also directs the Center for Studies in Music Technology at Yale University. The JAES paper [1] uses a "cost function" to evaluate the progress of a noise-removing algorithm, and steer its progress in the proper direction.
The second article [2] describes how this method, and others, were applied to an audio recording of Johannes Brahms, himself, playing a segment of his "Hungarian Dance No. 1" at the piano.
The authors created a synthesized sound file from their analyzed data (I'm not sure if it was .wav. or Midi) and "overlaid" it with the original Brahms sound record to test their analysis results.
Artis's desire is rather thought-provoking. She is currently editing the set of 12 piano rolls recorded in 1923 by Jelly Roll Morton, and adding realistic velocities/expression in preparation for playback on a Midi solenoid reproducing piano. I presume that, at the current stage of editing, the timing is very metronomic, and even with expression and accents, it still sounds a little too good, i.e., "unreal". Simply introducing a little random noise into the Midi file timing just make the song sound "live-played" sounds like an umpteenth-generation piano roll copy, because the random timing is truly random.
Howzat again? Yes: true random noise on the time base doesn't sound right, either. Therefore, the original performer was NOT random in his timing, and there must be some sort of correlation with the musical figure he's performing.
Artis would welcome constructive advice on this task. Any ideas out there?
-- Robbie Rhodes <rrhodes@foxtail.com> 30 October 1995 |
(Message sent Tue 31 Oct 1995, 05:03:26 GMT, from time zone GMT-0800.) |
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