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2023.12.28
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sshlien
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doc/CHANGES
24
doc/CHANGES
@@ -15182,6 +15182,28 @@ case statements were removed since they are unnecessary.
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December 28 2023
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abc2midi: tuplet bug
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The following example produces the error
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Warning in line-char 7-8 : Different length notes in tuple
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X:1
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T:Test
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L:1/4
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Q:1/4=90
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M:3/4
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K:D
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(3[ac']/d'/[ac']/ [ac']/z/ |
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Analysis: though it is legal to have different length notes (and
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rests) in a tuple, this is clearly a bug. The message occurs in the
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function event_note() in store.c. tnote_num and tnote_denom should
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contain the expected length of the note in the tuple based on the
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first note encountered in the tuple. The value of tnote_denom was
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not adjusted by event_chordoff to compensate by the length value
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specified at the end of the [ac'] chord, resulting in the problem.
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107
doc/drums.txt
107
doc/drums.txt
@@ -1,107 +0,0 @@
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Advamced Percussion Analysis
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in the Midistats Program
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This is an addendum to the midistats.1 file.
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The MIDI file devotes channel 9 to the percussion instruments
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and over 60 percussion instruments are defined in the MIDI
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standard. Though there is a lot of diversity in the percussion
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track, for most MIDI files only the first 10 or so percussion
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instruments are important in defining the character of the track. The
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program Midiexplorer has various tools for exposing the percussion
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channel which are described in the documentation. The goal
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here is to find the essential characteristics of the percussion
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track which distinguishes the MIDI files. This is attempted
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in the program midistats. Here is a short description.
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-corestats
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Produces a line with 5 numbers separated by tabs. eg
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1 8 384 4057 375
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It returns the number of tracks, the number of channels, the
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number of divisions per quarter note beat (ppqn),
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the number of note onsets in the midi file, and the maximum
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number of quarter note beats in midi file.
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-pulseanalysis
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Counts the number of note onsets as a function of its onset time
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relative to a beat, grouping them into 12 intervals and returns
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the result as a discrete probability density function. Generally,
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the distribution consists of a couple of peaks corresponding
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to quarter notes or eigth notes. If the distribution is flat,
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it indicates that the times of the note occurrences have not been
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quantized into beats and fractions. Here is a sample output.
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0.3496,0.0000,0.0000,0.1602,0.0000,0.0002,0.2983,0.0000,0.0000,0.1914,0.0002,0.0001
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-panal
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Counts the number of note onsets for each percussion instrument. The first
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number is the code (pitch) of the instrument, the second number is the
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number of occurrences. eg.
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35 337 37 16 38 432 39 208 40 231 42 1088 46 384 49 42 54 1104 57 5 70 1040 85 16
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-ppatfor n
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where n is the code number of the percussion instrument. Each beat
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is represented by a 4 bit number where the position of the on-bit
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indicates the time in the beat when the drum onset occurs. The bits
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are ordered from left to right (higher order bits to lower order
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bits). This is the order of bits that you would expect in a
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time series.
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Thus 0 indicates that there was no note onset in that beat, 1 indicates
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a note onset at the end of the beat, 4 indicates a note onset
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in the middle of the beat, and etc. The function returns a string
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of numbers ranging from 0 to 7 indicating the presence of note onsets
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for the selected percussion instrument for the sequence of beats
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in the midi file. Here is a truncated sample of the output.
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0 0 0 0 0 0 0 0 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 4 4 0
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1 0 0 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 0 0
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1 0 5 0 1 0 5 0 1 etc.
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One can see a repeating 4 beat pattern.
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-ppat
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midistats attempts to find two percussion instruments in the midi file
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which come closest to acting as the bass drum and snare drum.
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If it is unsuccessful, it returns a message of its failue. Otherwise,
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encodes the position of these drum onsets in a 8 bit byte for each
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quarter note beat in the midi file. The lower (right) 4 bits encode the
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bass drum and the higher (left) 4 bits encode the snare drum in the
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same manner as described above for -ppatfor.
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0 0 0 0 0 0 0 0 0 0 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145
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33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145
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33 145 33 145 33 145 33 145 33 145 33 and etc.
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-ppathist
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computes and displays the histogram of the values that would appear
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when running the -ppat. eg.
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bass 35 337
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snare 38 432
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1 (0.1) 64 32 (2.0) 8 33 (2.1) 136 144 (9.0) 8 145 (9.1) 136
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The bass percussion code, the number of onsets, and the snare
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percussion code and the number of onsets are given in the
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first two lines. In the next line the number of occurrences of
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each value in the -ppat listing is given. The number in parentheses
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splits the two 4-bit values with a period. Thus 33 = (2*16 + 1).
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-nseqfor -n
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Note sequence for channel n. This option produces a string for bytes
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indicating the presence of a note in a time unit corresponding to
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an eigth note. Thus each quarter note beat is represented by two
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bytes. The pitch class is represented by the line number on the
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staff, where 0 is C. Thus the notes on a scale are represented
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by 7 numbers, and sharps and flats are ignored. The line number is
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then converted to a bit position in the byte, so that the pitch
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classes are represented by the numbers 1,2,4,8, and etc. A chord
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of consisting of two note onsets would set two of the corresponding
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bits. If we were to represent the full chromatic scale consisting
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of 12 pitches, then we would require two-byte integers or
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twice of much memory.
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Though the pitch resolution is not sufficient to distinguish
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major or minor chords, it should be sufficient to be identify some
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repeating patterns.
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182
doc/midistats.1
182
doc/midistats.1
@@ -1,4 +1,4 @@
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.TH MIDISTATS 1 "17 November 2023"
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.TH MIDISTATS 1 "27 December 2023"
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.SH NAME
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\fBmidistats\fP \- program to summarize the statistical properties of a midi file
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.SH SYNOPSIS
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@@ -55,6 +55,8 @@ file.
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.PP
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pitchbends specifies the total number of pitchbends in this file.
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.PP
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pitchbendin c n specifies the number of pitchbends n in channel c
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.PP
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progs is a list of all the midi programs addressed
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.PP
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progsact the amount of activity for each of the above midi programs.
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@@ -74,9 +76,20 @@ instruments.
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pitches is a histogram for the 11 pitch classes (C, C#, D ...B)
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that occur in the midi file.
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.PP
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key indicates the key of the music, the number of sharps (positive) or
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flats (negative) in the key signature, and a measure of the confidence
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in this key signature. The key was estimated from the above pitch histogram.
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A confidence level below 0.4 indicates that the pitch histogram does
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not follow the histogram of a major or minor scale. (It may be the
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result of a mixture of two key signatures.)
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.PP
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pitchact is a similar histogram but is weighted by the length of
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the notes.
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.PP
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chanvol indicates the value of the control volume commands in the
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midi file for each of the 16 channels. The maximum value is 127.
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It scales the loudness of the notes (velocity) by its value.
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.PP
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chnact returns the amount of note activity in each channel.
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.PP
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trkact returns the number of notes in each track.
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@@ -87,21 +100,172 @@ all channels except the percussion channel.
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collisions. Midistats counts the bar rhythm patterns using a hashing
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function. Presently collisions are ignored so occasionally two
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distinct rhythm patterns are counted as one.
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.SH Advance Percussion Analysis Tools
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.PP
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In addition the midistats may return other codes that describe
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other characteristics. They include
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unquantized - the note onsets are not quantized
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.br
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triplets - 3 notes played in the time of 2 notes are present
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.br
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qnotes - the rhythm is basically simple
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.br
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clean_quantization - the note onsets are quantized into 1/4, 1/8, 1/16 time units.
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.br
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dithered_quantization - small variations in the quantized note onsets.
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.br
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Lyrics - lyrics are present in the meta data
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.br
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programcmd - there may be multiple program changes in a midi channel
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.SH Advanced Percussion Analysis Tools
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.PP
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The MIDI file devotes channel 9 to the percussion instruments
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and over 60 percussion instruments are defined in the MIDI
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standard. Though there is a lot of diversity in the percussion
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track, for most MIDI files only the first 10 or so percussion
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instruments are important in defining the character of the track. The
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program Midiexplorer has various tools for exposing the percussion
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channel which are described in the documentation. The goal
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here is to find the essential characteristics of the percussion
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track which distinguishes the MIDI files. This is attempted
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in the program midistats. Here is a short description.
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.br
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A number of experimental tools for analyzing the percussion channel
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(track) were introduced into midistats and are accessible through
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the runtime arguments. When these tools are used in a script which
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runs through a collection of midi files, you can build a database
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of percussion descriptors. Some more details are given in the
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file drums.txt which comes with this documentation.
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of percussion descriptors.
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.SH OPTIONS
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.TP
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.B -corestats
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.TP
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.B -pulseanalysis
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.TP
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.PP
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-corestats
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.br
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outputs a line with 5 numbers separated by tabs. eg
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.br
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1 8 384 4057 375
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.br
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It returns the number of tracks, the number of channels, the
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number of divisions per quarter note beat (ppqn),
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the number of note onsets in the midi file, and the maximum
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number of quarter note beats in midi file.
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.PP
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-pulseanalysis
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.br
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counts the number of note onsets as a function of its onset time
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relative to a beat, grouping them into 12 intervals and returns
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the result as a discrete probability density function. Generally,
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the distribution consists of a couple of peaks corresponding
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to quarter notes or eigth notes. If the distribution is flat,
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it indicates that the times of the note occurrences have not been
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quantized into beats and fractions. Here is a sample output.
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.br
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0.349,0.000,0.000,0.160,0.000,0.000,0.298,0.000,0.000,0.191,0.000,0.000
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.PP
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-panal
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.br
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Counts the number of note onsets for each percussion instrument. The first
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number is the code (pitch) of the instrument, the second number is the
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number of occurrences. eg.
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.br
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35 337 37 16 38 432 39 208 40 231 42 1088 46 384 49 42 54 1104 57 5 70 1040 85 16
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.PP
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-ppatfor n
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.br
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where n is the code number of the percussion instrument. Each beat
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is represented by a 4 bit number where the position of the on-bit
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indicates the time in the beat when the drum onset occurs. The bits
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are ordered from left to right (higher order bits to lower order
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bits). This is the order of bits that you would expect in a
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time series.
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Thus 0 indicates that there was no note onset in that beat, 1 indicates
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a note onset at the end of the beat, 4 indicates a note onset
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in the middle of the beat, and etc. The function returns a string
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of numbers ranging from 0 to 7 indicating the presence of note onsets
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for the selected percussion instrument for the sequence of beats
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in the midi file. Here is a truncated sample of the output.
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.br
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0 0 0 0 0 0 0 0 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 0 0 4 1 4 4 0
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1 0 0 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 5 0 1 0 0 0
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1 0 5 0 1 0 5 0 1 etc.
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.br
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One can see a repeating 4 beat pattern.
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.PP
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-ppat
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.br
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midistats attempts to find two percussion instruments in the midi file
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which come closest to acting as the bass drum and snare drum.
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If it is unsuccessful, it returns a message of its failue. Otherwise,
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encodes the position of these drum onsets in a 8 bit byte for each
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quarter note beat in the midi file. The lower (right) 4 bits encode the
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bass drum and the higher (left) 4 bits encode the snare drum in the
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same manner as described above for -ppatfor.
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.br
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0 0 0 0 0 0 0 0 0 0 33 145 33 145 33 145 33 145 33 145 33 145 33 145
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.br
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33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145 33 145
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.br
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33 145 33 145 33 145 33 145 33 145 33 and etc.
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.PP
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-ppathist
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.br
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computes and displays the histogram of the values that would appear
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when running the -ppat. eg.
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.br
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bass 35 337
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.br
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snare 38 432
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.br
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1 (0.1) 64 32 (2.0) 8 33 (2.1) 136 144 (9.0) 8 145 (9.1) 136
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.br
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The bass percussion code, the number of onsets, and the snare
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percussion code and the number of onsets are given in the
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first two lines. In the next line the number of occurrences of
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each value in the -ppat listing is given. The number in parentheses
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splits the two 4-bit values with a period. Thus 33 = (2*16 + 1).
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.PP
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-pitchclass
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.br
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Returns the pitch class distribution for the entire midi file.
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.PP
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-nseqfor
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.br
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Note sequence for channel n. This option produces a string of bytes
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indicating the presence of a note in a time unit corresponding to
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an eigth note. Thus each quarter note beat is represented by two
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bytes. The pitch class is represented by the line number on the
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staff, where 0 is C. Thus the notes on a scale are represented
|
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by 7 numbers, and sharps and flats are ignored. The line number is
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then converted to a bit position in the byte, so that the pitch
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classes are represented by the numbers 1,2,4,8, and etc. A chord
|
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of consisting of two note onsets would set two of the corresponding
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bits. If we were to represent the full chromatic scale consisting
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of 12 pitches, then we would require two-byte integers or
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twice of much memory.
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.br
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Though the pitch resolution is not sufficient to distinguish
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major or minor chords, it should be sufficient to be identify some
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repeating patterns.
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-ver (version number)
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.B etc. (See drums.txt in doc folder.)
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@@ -6,7 +6,7 @@ abc2abc version 2.20 February 07 2023
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yaps version 1.92 January 06 2023
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abcmatch version 1.82 June 14 2022
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midicopy version 1.39 November 08 2022
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midistats version 0.82 December 17 2023
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midistats version 0.83 December 26 2023
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24th January 2002
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Copyright James Allwright
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Reference in New Issue
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