calculate absolute seconds for midi notes using midilib in ruby, plus some pretty file summary
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File Summary
SEQ PPQN:192 TRACKS:2
TRACK [00] EVENTS:6
\CHAN[00] PROGS: 1 <Acoustic Grand Piano>
\TEMPO 500000 BPM: 120
\TEMPO 1000000 BPM: 60
\TEMPO 2000000 BPM: 30
TRACK [01] EVENTS:13
\CHAN[00] NOTES: 6 (A#4- C5) [ 2] <C5,A#4>
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Tempo to seconds map
TEMPO BPM:120 START: 0/ 0.0000 END: 764/ 1.9896 DURATION: 1.9896
TEMPO BPM: 60 START: 764/ 1.9896 END: 1535/ 6.0052 DURATION: 4.0156
TEMPO BPM: 30 START: 1535/ 6.0052 END: 2302/13.9948 DURATION: 7.9896
NOTE C5 ( 72) CH:00 TIME: 0/ 0.0000
NOTE A#4 ( 70) CH:00 TIME: 384/ 1.0000
NOTE C5 ( 72) CH:00 TIME: 768/ 2.0104
NOTE A#4 ( 70) CH:00 TIME: 1152/ 4.0104
NOTE C5 ( 72) CH:00 TIME: 1536/ 6.0156
NOTE A#4 ( 70) CH:00 TIME: 1920/10.0156