MIDI composition with {dplyr}, {midiblender}, and {pyramidi}

midiblender
pyramidi
rstats
dplyr
midi composition
Trying some dplyr composition patterns for creating midi files
Author

Matt Crump

Published

February 12, 2024

Code 
from diffusers import DiffusionPipeline
from transformers import set_seed
from PIL import Image
import torch
import random
import ssl
import os
ssl._create_default_https_context = ssl._create_unverified_context

#locate library
#model_id = "./stable-diffusion-v1-5"
model_id = "dreamshaper-xl-turbo"

pipeline = DiffusionPipeline.from_pretrained(
    pretrained_model_name_or_path = "../../../../bigFiles/huggingface/dreamshaper-xl-turbo/"
)

pipeline = pipeline.to("mps")

# Recommended if your computer has < 64 GB of RAM
pipeline.enable_attention_slicing("max")

prompt = "composing music with rstats. dplyr musical notes. tidyverse. hexagons everywhere. 3d. music inside hexagons floating in the universe. musical notes inside the hexagons. cartoon. linocut"

for s in range(30):
  for n in [5,10]:
    seed = s+21
    num_steps = n+1
    set_seed(seed)
    
    image = pipeline(prompt,height = 1024,width = 1024,num_images_per_prompt = 1,num_inference_steps=num_steps)
    
    image_name = "images/synth_{}_{}.jpeg"
    
    image_save = image.images[0].save(image_name.format(seed,num_steps))

Massive modular synthesizer. Eurorack modular synthesizer. Huge synthesizer room, full or modular synthesizers with patch cords connecting everywer. 80s cartoon. Linocut. - dreamshaper

This morning I added some dplyr style functions to midiblender for row-by-row, explicit construction of a data frame containing midi information. I’ll provide some examples here, and use this post to try a few compositional goals with the dplyr approach.

pyramidi also has examples of composition with dplyr syntax that are worth checking out. My approach relies on several pyramidi internal functions, and is pretty similar overall.

Midi dataframe construction with {dplyr}

Some of these examples are also in the vignette, Midi data frame constructors with dplyr.

The following block of code shows an example of systematically creating a midi data frame, on a row-by-row basis. The functions are mostly wrappers to dplyr::add_row, but they have midi variables in them.

Functions that add a row start with “add”, which makes them easy to find with autocomplete while programming. These functions also pass ..., which is useful for placing a row .before or .after another row.

This code block writes important meta messages, shows that it is possible to write program_change and control_change messages, and writes a couple notes before ending the track.

Code 
library(midiblender)
library(pyramidi)

new_midi_df <- create_empty_midi_df() %>% # initialize columns
  add_meta_track_name(name = "My track") %>%
  add_meta_tempo(tempo = 500000) %>%
  add_meta_time_sig(numerator = 4,
                    denominator = 4,
                    clocks_per_click = 36,
                    notated_32nd_notes_per_beat = 8) %>%
  add_program_change(program = 0,
                     channel = 0) %>%
  add_control_change(control = 0,value = 0) %>%
  add_note_on(time = 0,note = 60) %>%
  add_note_off(time = 8,note = 60) %>%
  add_meta_end_of_track()

# print the data frame.
knitr::kable(new_midi_df)
i_track meta type name time numerator denominator clocks_per_click notated_32nd_notes_per_beat program channel control value note velocity tempo
0 TRUE track_name My track 0 NA NA NA NA NA NA NA NA NA NA NA
0 TRUE set_tempo NA 0 NA NA NA NA NA NA NA NA NA NA 5e+05
0 TRUE time_signature NA 0 4 4 36 8 NA NA NA NA NA NA NA
0 FALSE program_change NA 0 NA NA NA NA 0 0 NA NA NA NA NA
0 FALSE control_change NA 0 NA NA NA NA NA 0 0 0 NA NA NA
0 FALSE note_on NA 0 NA NA NA NA NA 0 NA NA 60 0 NA
0 FALSE note_off NA 8 NA NA NA NA NA 0 NA NA 60 0 NA
0 TRUE end_of_track NA 0 NA NA NA NA NA NA NA NA NA NA NA

Pyramidi object creation and export

This shows how to take a midi dataframe like the above, and export it to disk as a .mid file.

First, pyramidi::MidiFramer$new() creates a new pyramidi object.

Upon creation, it is possible to update new_pyramidi_object$ticks_per_beat with a new value. I believe the default value is 960L, and the code below updates it to a smaller value.

The new_midi_df from above is then updated within the pyramidi object using new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(new_midi_df).

Finally, new_pyramidi_object$mf$write_file("file_name.mid") writes the file to disk.

Code 
#Initialize new pyramidi object
new_pyramidi_object <- pyramidi::MidiFramer$new()

# update ticks per beat
new_pyramidi_object$ticks_per_beat <- 96L

# update object with new midi df
new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(new_midi_df)

# write to midi file
new_pyramidi_object$mf$write_file("file_name.mid")

Composing with a wide data frame, then pivoting to long

Midi files writes note_on and note_off messages in succession with time stamps coding relative time since the last message. For composition, it may be convenient to work with a wider data frame.

Here’s an example of using dplyr to create a series of notes over time. The notes are randomly chosen from the vector possible_notes. The rhythm defining when a note occurs is generated by bresenham_euclidean(), which can produce some nice sounding rhythms. The code chunk will generate as many bars as defined in bars, and the shortest note is a 16th note.

Code 
library(dplyr)

# note parameters
bars <- 4 # number of bars
bar_time_steps <- 16 # number of time steps in a bar
note_duration <- 24 # note duration in ticks
possible_notes <- c(60, 63, 65, 66, 67, 70, 72, 75) # midi note values to pick

# create a tibble to compose notes in time 
compose_notes <- tibble::tibble(note_id = integer(),
                             note = integer(),
                             beat_on = integer(),
                             note_on = integer(),
                             note_off = integer()) %>%
  # add multiple bars worth of notes
  add_row(beat_on = c(replicate(bars,bresenham_euclidean(sample(c(2:15),1),
                                            bar_time_steps,
                                            start=1))),
          note = sample(possible_notes, 
                        size = bar_time_steps*bars, 
                        replace= TRUE)
          ) %>%
  # handle note times
  mutate(note_id = 1:n(),
         note_on = (1:n()-1)*note_duration,
         note_off = note_on+note_duration) %>%
  # keep events where a beat occurred
  filter(beat_on == 1) 

#print to show
knitr::kable(head(compose_notes))
note_id note beat_on note_on note_off
1 65 1 0 24
9 72 1 192 216
17 63 1 384 408
19 65 1 432 456
20 72 1 456 480
21 72 1 480 504

At this point the compose_notes dataframe contains note_on and note_off information in wide format. A quick call to tidyr::pivot_longer, along with subtracting the time stamps to get them into relative time, and we have a dataframe that is nearly ready for export.

Code 
compose_notes <- compose_notes %>%
  # pivot to long
  tidyr::pivot_longer(c("note_on","note_off"),names_to="type",values_to="time") %>%
  # relative time
  mutate(time = time - lag(time,default=0))

#print to show
knitr::kable(head(compose_notes))
note_id note beat_on type time
1 65 1 note_on 0
1 65 1 note_off 24
9 72 1 note_on 168
9 72 1 note_off 24
17 63 1 note_on 168
17 63 1 note_off 24

Now we have a body of midi messages. The last step is to put them into a full-fledged midi dataframe, and export them.

Code 
# create new midi_df

## add to a new midi df
new_midi_df <- create_empty_midi_df() %>% # initialize
  add_meta_track_name(name = "My track") %>%
  add_meta_tempo(tempo = 500000) %>%
  add_meta_time_sig(
    numerator = 4,
    denominator = 4,
    clocks_per_click = 36,
    notated_32nd_notes_per_beat = 8
  ) %>%
  add_program_change(program = 0,
                     channel = 0) %>%
  add_control_change(control = 0, value = 0) %>%
  # add new notes <---------------Adding stuff from compose_notes
  add_row(i_track = rep(0,dim(compose_notes)[1]), 
          meta = rep(FALSE,dim(compose_notes)[1]),
          note = compose_notes$note,
          type = compose_notes$type,
          time = compose_notes$time,
          velocity = 64) %>%
  add_meta_end_of_track()

#write midi

#Initialize new pyramidi object
new_pyramidi_object <- pyramidi::MidiFramer$new()
# update ticks per beat
new_pyramidi_object$ticks_per_beat <- 96L
# update object with new midi df
new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(new_midi_df)
# write to midi file
new_pyramidi_object$mf$write_file("file_name.mid")

Making it less of a wall of code

I’m not working on this right now. Going with walls of code.

Frequency biased sequences

I’ve got a project coming up where I will likely need to generate a whole bunch of “musical” sequences with specific kinds of statistical structure. I’m not sure whether I will use the {dplyr} style code for this. This is a note to future self about what it might look like.

  • got something that will work later
  • need to write functions for creating unequal frequency vectors with specific constraints
  • Move development on this issue to another castle.
Code 
# note parameters
bars <- 4
possible_time_steps <- 16
note_duration <- 24
possible_notes <- c(60, 63, 65, 66, 67, 70, 72, 75)

total_notes <- 8
total_beats <- bars*possible_time_steps

# need to work out some algorithms for unequal frequency distribution generation, these are enough for an example
equal_frequencies <- rep(total_beats/8,8)
half_frequencies <- equal_frequencies + (equal_frequencies * rep(c(.5,-.5),each = total_notes/2))
most_unequal_frequencies <- c(rep(1,(total_notes-1)),(total_notes*(total_notes-1)+1))

note_frequency_matrix <- rbind(equal_frequencies,
                              half_frequencies,
                              most_unequal_frequencies)

compose_notes <- tibble::tibble(note_id = integer(),
                             note = integer(),
                             beat_on = integer(),
                             note_on = integer(),
                             note_off = integer()) %>%
  # 1 beat every time_step
  rowwise() %>%
  add_row(beat_on = 1,
          note = sample(rep(sample(possible_notes),
                     times = note_frequency_matrix[3,])),
          ) %>%
  ungroup() %>%
  # handle note times
  mutate(note_id = 1:n(),
         note_on = (1:n()-1)*note_duration,
         note_off = note_on+note_duration) %>%
  filter(beat_on == 1) %>%
  #pivot to long
  tidyr::pivot_longer(c("note_on","note_off"),names_to="type",values_to="time") %>%
  mutate(time = time - lag(time,default=0))

## add to a new midi df
new_midi_df <- create_empty_midi_df() %>% # initialize
  add_meta_track_name(name = "My track") %>%
  add_meta_tempo(tempo = 500000) %>%
  add_meta_time_sig(
    numerator = 4,
    denominator = 4,
    clocks_per_click = 36,
    notated_32nd_notes_per_beat = 8
  ) %>%
  add_program_change(program = 0,
                     channel = 0) %>%
  add_control_change(control = 0, value = 0) %>%
  #use dplyr::add_row to add a bunch of notes
  add_row(i_track = rep(0,dim(compose_notes)[1]), 
          meta = rep(FALSE,dim(compose_notes)[1]),
          note = compose_notes$note,
          type = compose_notes$type,
          time = compose_notes$time,
          velocity = 64) %>%
  add_meta_end_of_track()

#write midi
#Initialize new pyramidi object
new_pyramidi_object <- pyramidi::MidiFramer$new()
# update ticks per beat
new_pyramidi_object$ticks_per_beat <- 96L
# update object with new midi df
new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(new_midi_df)
# write to midi file
new_pyramidi_object$mf$write_file("most_unequal.mid")

12-bar blues sequence

I like a good blues scale. Undoubtedly, whatever happens next won’t be bluesy, but that’s ok.

Algorithm components

  1. Sample notes from a blues scale
  2. Eavery bar, randomly sample a euclidean rhythm to fill the bar
  3. randomly assign notes to the beats in the euclidean rhythm
  4. Create a few tracks of this.
  5. try shifting chords, do 12 bar blues

Got it working, nice

Code 
all_tracks <- data.frame()
# loop for each track
for(t in 1:3) {
  
  # note parameters
  bars <- 12 * 4 * 4
  possible_time_steps <- 16
  note_duration <- 24
  possible_notes <- c(60, 63, 65, 66, 67, 70, 72, 75)
  
  key_vector <- rep(rep(c(0,0,0,0,5,5,0,0,7,5,0,7),each=possible_time_steps),4*4)
  
  compose_notes <- tibble::tibble(
    note_id = integer(),
    note = integer(),
    beat_on = integer(),
    note_on = integer(),
    note_off = integer()
  ) %>%
    # use euclidean rhythm
    rowwise() %>%
    add_row(
      beat_on = c(replicate(
        bars,
        bresenham_euclidean(sample(c(1, 2, 2, 2, 3, 4,5,5,6, 8, 15), 1),
                            possible_time_steps,
                            start = 1)
      )),
      note = sample(possible_notes,
                    size = possible_time_steps * bars,
                    replace = TRUE) + key_vector
    ) %>%
    ungroup() %>%
    # handle note times
    mutate(
      note_id = 1:n(),
      note_on = (1:n() - 1) * note_duration,
      note_off = note_on + note_duration
    ) %>%
    filter(beat_on == 1) %>%
    #pivot to long
    tidyr::pivot_longer(c("note_on", "note_off"),
                        names_to = "type",
                        values_to = "time") %>%
    mutate(time = time - lag(time, default = 0))
  ######################
  # End composition 
  
  #######################
  ## add composition to a new midi df
  new_midi_df <- create_empty_midi_df() %>% # initialize
    add_meta_track_name(name = "My track") %>%
    add_meta_tempo(tempo = 500000) %>%
    add_meta_time_sig(
      numerator = 4,
      denominator = 4,
      clocks_per_click = 36,
      notated_32nd_notes_per_beat = 8
    ) %>%
    add_program_change(program = 0,
                       channel = 0) %>%
    add_control_change(control = 0, value = 0) %>%
    # Composition added here
    add_row(
      i_track = rep(0, dim(compose_notes)[1]),
      meta = rep(FALSE, dim(compose_notes)[1]),
      note = compose_notes$note,
      type = compose_notes$type,
      time = compose_notes$time,
      velocity = 64
    ) %>%
    add_meta_end_of_track() %>%
    mutate(i_track = t) # set current track number
  
  all_tracks <- rbind(all_tracks,new_midi_df)
  
}

#write midi
#Initialize new pyramidi object
new_pyramidi_object <- pyramidi::MidiFramer$new()
# update ticks per beat
new_pyramidi_object$ticks_per_beat <- 96L
# update object with new midi df
new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(all_tracks)
# write to midi file
new_pyramidi_object$mf$write_file("bluesy_A.mid")

I put three midi tracks into ableton, added synth voices and drums, and that’s what it sounds like.

Hmmm, the dplyr style worked out. I didn’t think it would be so easy to get a 12-bar blues thing going. It still sounds like a computer made it, but a computer did make it, so that’s fair.

Adding parameters per track in a list.

Code 
library(midiblender)
library(dplyr)
library(pyramidi)

all_tracks <- data.frame()

# note parameters
  bars <- 12 * 4 * 4
  possible_time_steps <- 16
  note_duration <- 24
  
  track_params <- list(track_1_bass =
                         list(possible_notes = rep(60:72,   #1     2     3  4     5     6     7  8 
                                                   times = c(6, 0, 3, 0, 0, 3, 0, 3, 0, 0, 3, 0, 6)), 
                            key_vector = rep(rep(c(0, 0, 0, 0, 5, 5, 0, 0, 7, 5, 0, 7), 
                                                 each = possible_time_steps), 
                                             times = 4 * 4)
                           ),
                       track_2_mid =
                         list(possible_notes = rep(60:72,   #1     2     3  4     5     6     7  8 
                                                   times = c(6, 0, 2, 0, 0, 2, 0, 3, 0, 0, 3, 0, 6)), 
                            key_vector = rep(rep(c(0, 0, 0, 0, 5, 5, 0, 0, 7, 5, 0, 7), 
                                                 each = possible_time_steps), 
                                             times = 4 * 4)
                          ),
                       track_3_mid =
                         list(possible_notes = rep(60:72,   #1     2     3  4     5     6     7  8 
                                                   times = c(1, 0, 0, 2, 0, 3, 2, 3, 0, 0, 2, 0, 1)), 
                            key_vector = rep(rep(c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), 
                                                 each = possible_time_steps), 
                                             times = 4 * 4)
                          )
  )
                       
                           
# loop for each track
for(t in 1:3) {
  
  compose_notes <- tibble::tibble(
    note_id = integer(),
    note = integer(),
    beat_on = integer(),
    note_on = integer(),
    note_off = integer()
  ) %>%
    # use euclidean rhythm
    rowwise() %>%
    add_row(
      beat_on = c(replicate(
        bars,
        bresenham_euclidean(sample(c(1, 2, 2, 3, 4, 5, 5, 6, 8, 11, 13), 1), 
                            possible_time_steps,
                            start = 1)
      )),
      note = sample(track_params[[t]]$possible_notes,
                    size = possible_time_steps * bars,
                    replace = TRUE) + track_params[[t]]$key_vector
    ) %>%
    ungroup() %>%
    # handle note times
    mutate(
      note_id = 1:n(),
      note_on = (1:n() - 1) * note_duration,
      note_off = note_on + note_duration
    ) %>%
    filter(beat_on == 1) %>%
    #pivot to long
    tidyr::pivot_longer(c("note_on", "note_off"),
                        names_to = "type",
                        values_to = "time") %>%
    mutate(time = time - lag(time, default = 0))
  ######################
  # End composition 
  
  #######################
  ## add composition to a new midi df
  new_midi_df <- create_empty_midi_df() %>% # initialize
    add_meta_track_name(name = "My track") %>%
    add_meta_tempo(tempo = 500000) %>%
    add_meta_time_sig(
      numerator = 4,
      denominator = 4,
      clocks_per_click = 36,
      notated_32nd_notes_per_beat = 8
    ) %>%
    add_program_change(program = 0,
                       channel = 0) %>%
    add_control_change(control = 0, value = 0) %>%
    # Composition added here
    add_row(
      i_track = rep(0, dim(compose_notes)[1]),
      meta = rep(FALSE, dim(compose_notes)[1]),
      note = compose_notes$note,
      type = compose_notes$type,
      time = compose_notes$time,
      velocity = 64
    ) %>%
    add_meta_end_of_track() %>%
    mutate(i_track = t) # set current track number
  
  all_tracks <- rbind(all_tracks,new_midi_df)
  
}

#write midi
#Initialize new pyramidi object
new_pyramidi_object <- pyramidi::MidiFramer$new()
# update ticks per beat
new_pyramidi_object$ticks_per_beat <- 96L
# update object with new midi df
new_pyramidi_object$mf$midi_frame_unnested$update_unnested_mf(all_tracks)
# write to midi file
new_pyramidi_object$mf$write_file("bluesy_C.mid")