Assignment 5: The Music Editor: First Movement
Due: Fri 10/21 at 8:59pm; self-evaluation due Sat 10/22 at 8:59pm
This assignment is to be completed solo. Subsequent homeworks will be done in pairs.
Start looking for partners now, and email Sam Berin (berin.s@husky)
with both your usernames. You will not be able to submit subsequent homeworks
until we create a team for you on the handin server.
1 Editing Music
Your goal in this series of homework assignments is to construct a music editor in the classic Model-View-Controller architecture. This week’s assignment is to construct the model for your editor. There is no starter code for this assignment. You need to design, implement and test your model from scratch...without knowing precisely what the view or controller will need from you.1You also may not personally know much about musical notation or theory. That is not actually an impediment to implementing these assignments: just be careful and methodical about your design, based on the information here.
Please place all your code in the cs3500.music.model package.
1.1 Some background on music
Distilled to its mechanical essence, music is simply playing a collection of tones for varying durations on various instruments at various volumes at varying times. Each tone is called a pitch, and there are twelve distinct pitches in the Western system of music. The thirteenth pitch “sounds the same” to our ears, and so we say it is the “same” pitch in a different octave.2This is the so-called “chromatic scale”. Other musical systems use a five-pitch-per-octave, or pentatonic, scale (common in Asian music); others use twenty-four (common in Slavic music); still other systems forego obvious note names entirely (common in African music). We give these notes names:
C C♯ D D♯ E F F♯ G G♯ A A♯ B
and the note after B is again C. (I am simplifying the names of
the notes here; the note C♯, pronounced “Cee-sharp” is the same note
as “Dee-flat”, written D♭; notes without these “accidentals” are
called natural. Those of you familiar with piano keyboards will note
that the white keys correspond to the natural note names, while the black keys
correspond to the sharps.) Typical human hearing can detect about ten octaves
of notes. For example, so-called “middle C”3So named because
it’s roughly in the middle of most people’s speaking voices. is the fourth
octave people can hear, and thus written C4; the note fifteen notes
higher is D♯5. You can, of course, just label every note by a number,
but names are ever so much easier to read and remember.
In addition to pitch, notes have a duration. Typical pieces have a rhythm to them, called a measure, that is usually three or four beats long. (Most pop, rock, or hip-hop music is typically four beats per measure; some classical forms such as waltzes are three beats per measure.) A note’s duration is measured in beats, and can in general be any integer multiple of any integer power of two beats long. A “quarter note” is one beat long (and is 1/4 of a 4-beat measure); a “half note” is two beats long (half of a 4-beat measure); a “whole note” is a full measure long. There can also be eighth notes (half a beat), sixteenth notes (1/4 of a beat), etc. For this assignment, you may simplify your model and only represent notes that are an integral number of beats long.
When no notes are playing, we say the music has a rest, which is likewise measured in beats.
Music also has dynamics describing how the volume changes during the performance of a piece. For now, you can ignore dynamics, and consider everything to be played at a constant volume.
Some music is very simple, and consists of at most one note played at a time
—
1.2 How is music written?
Some ideas:
We might easily want to write music one note at a time.
We might want to edit or remove existing notes.
We might want to combine two pieces of music such that they play simultaneously.
We might want to combine two pieces of music such that they play consecutively.
Other operations are surely possible.
1.3 What should the music editor eventually look like?
Shown here are two screenshots of a possible music editor view that you might write. In both images, higher pitches are higher vertically, and time increases to the right. Every row is a particular pitch, and beat numbers are marked at the top. Vertical bars mark measure lines every four beats:
In the first image, the onset of a note is drawn black, while all remaining beats of the note are drawn green. In the second, all beats are drawn blue, and the notes are shortened ever so slightly to distinguish one long note from several adjacent shorter ones. (Additionally, notes in the “current beat” are drawn in cyan, but you can ignore that fact in this assignment.) When you design your own views, you may choose whatever visual styling you wish, so long as the information is clear.
Here is an alternate view of the same piece, rendered as text in the console:
╔══════════════════════════════════════════════════════════════════════════════════╗ ║ E3 F3 F#3 G3 G#3 A3 A#3 B3 C4 C#4 D4 D#4 E4 F4 F#4 G4 ║ ║ 0 X X ║ ║ 1 | | ║ ║ 2 | X ║ ║ 3 | | ║ ║ 4 | X ║ ║ 5 | | ║ ║ 6 | X ║ ║ 7 | ║ ║ 8 X X ║ ║ 9 | | ║ ║10 | X ║ ║11 | | ║ ║12 | X ║ ║13 | | ║ ║14 | | ║ ║15 ║ ║16 X X ║ ║17 | | ║ ║18 | X ║ ║19 | | ║ ║20 | X ║ ║21 | | ║ ║22 | | ║ ║23 | | ║ ║24 X X ║ ║25 | | ║ ║26 X ║ ║27 | ║ ║28 X ║ ║29 | ║ ║30 | ║ ║31 | ║ ║32 X X ║ ║33 | | ║ ║34 | X ║ ║35 | | ║ ║36 | X ║ ║37 | | ║ ║38 | X ║ ║39 | | ║ ║40 X X ║ ║41 | | ║ ║42 | X ║ ║43 | | ║ ║44 | X ║ ║45 | | ║ ║46 | X ║ ║47 | | ║ ║48 X X ║ ║49 | | ║ ║50 | X ║ ║51 | | ║ ║52 | X ║ ║53 | | ║ ║54 | X ║ ║55 | | ║ ║56 X X ║ ║57 | | ║ ║58 | | ║ ║59 | | ║ ║60 | | ║ ║61 | | ║ ║62 | | ║ ║63 | | ║ ╚══════════════════════════════════════════════════════════════════════════════════╝
This view is exactly as informative as the first screenshot, just “turned” 90 degrees clockwise. (The “frame” around the display is not part of the output; it is merely there to make the boundaries of the display visible.)
As a technical specification: the output above consists of
A column of numbers representing the beats, printed right-justified and padded with leading spaces, that is exactly as wide as necessary. (So if your piece is 999 beats long, it uses three columns of characters; if it’s 1000 beats long, it uses four.)
A sequence of columns, each five characters wide, representing each pitch. The first line prints out the names of the pitches, more-or-less centered within the five-character column. I.e.,
" F2 "and" G#3 "and" D#10". (Because we need to represent at least ten octaves, three-character columns won’t be wide enough.)Use exactly as many columns as are needed for your piece, from its lowest to its highest note.
Each note-head is rendered as an
" X ", and each note-sustain is rendered as" | ". When a note is not played, five spaces are rendered (as" ").As a consequence: every line should be exactly the same length, as shown above.
Every item, including the last one, ends in a newline.
Use the
#character (the standard hash or pound sign) to represent sharps, rather than the more correct♯, to avoid any formatting errors when running your code.
2 Assignment
Design a model to represent a piece of music. This may consist of one or more interfaces, abstract classes, concrete classes, enums, etc. Consider carefully what operations it should support, what invariants it assumes, etc.
Document your model.
Implement your model.
Test your model.
Implement the console rendering of your model, so we can visualize your data. We will not be autograding this assignment, but you’d do well to emulate the output above as precisely as possible, as we will be checking it (on models constructed from input files we provide) on future assignments.
Submit any files created in this assignment, along with a text README file explaining your design. Your readme file should give the graders an overview of what the purposes are for every class, interface, etc. that you include in your model, so that they can quickly get a high-level overview of your code. It does not replace the need for proper Javadoc!
3 Grading standards
For this assignment, you will be graded on
the design of your model interface(s), in terms of clarity, flexibility, and how plausibly it will support needed functionality;
the appropriateness of your representation choices for the data, and the adequacy of any documented class invariants,
the correctness and stylishness of your implementation, and
the comprehensiveness and correctness of your test coverage.
4 Submission
Please submit your homework to https://cs3500.ccs.neu.edu/ by the above deadline. Then be sure to complete your self evaluation by its due date.
1You also may not personally know much about musical notation or theory. That is not actually an impediment to implementing these assignments: just be careful and methodical about your design, based on the information here.
2This is the so-called “chromatic scale”. Other musical systems use a five-pitch-per-octave, or pentatonic, scale (common in Asian music); others use twenty-four (common in Slavic music); still other systems forego obvious note names entirely (common in African music).
3So named because it’s roughly in the middle of most people’s speaking voices.