Re: Analog to MIDI
By Karl Petersen
Larry Smith has presented the most complete and reasonable discussion I've heard of analog audio to MIDI conversion. The genetic approach did not exist when I began to survey the possibilities, and it appears to offer the necessary loops. I am just now reading through the last year's correspondence and will probably run across many letters on the subject, but I would like to note the concepts I have identified with their plusses and minuses.
1. Artistic recreation: A capable musician listens to the audio and recreates the performance on a MIDI recording. Musical ability to interpret the original recording and correlate from memory to the MIDI file and editing time are limitations.
2. Sonogram output edited into note events: Extremely messy data due to overlapping harmonics and loud notes blocking soft ones make this totally impractical in manual translation. [I have examples of sonograms of Ampico rolls that don't correlate even though they're the same data!]
3. Signature analysis through separately recording note signatures (or estimating them from solo audio notes) then performing stepwise identification of individual notes through process iteration: Notes do not play the same twice in harmonic content and decay. The big and separate notes come out marginally well, but the remainder are hidden in a field of hash that does not identify.
4. Number 3 but with subtraction of identified notes before analysis for the next note: This still leaves a field of hash after picking out the big ones.
5. Any or all of the above played back against the original audio by binaural comparison to assess the accuracy by time and stereo location shifts: This helps in the correlation, but gives no clue as to what technique is needed to make a fix.
The genetic analysis technique effectively does item 3 and 4 if I understand it correctly, and can unravel the Gordian knot with enough machine time.
The next question is, what hardware and software are necessary to give this a trial run? I have lots of overnight time available on DOS and UNIX workstations at home, and have my own resident AIX administrator and C-writer, but he has not osmosed the genetic algorithm recommended reading list.
Ok, Larry, Tag, you're It =).
Karl A. Petersen
3116 N. Hearth Ave.
Meridian, ID 83642
208) 884-3488 h
(208) 323-7124 w |
(Message sent Wed 11 Oct 1995, 21:58:28 GMT, from time zone GMT-0600.) |
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