I548/N560 HOMEWORK #2 (revised 8 Sept. 2007)

* EVERYONE:

PlayMelody_LoopV2.R, at:

    http://www.informatics.indiana.edu/donbyrd/Teach/RExamplePrograms

is an R program that plays a well-known melody -- the beginning of the main theme of
"Star Wars" -- but with all notes having the same duration. (1) Modify it to use the
correct relative durations, and play at a reasonable tempo. Actually, I'll give full
credit for any of three versions. Assuming the melody is in 2/2 or 4/4, the durations
are (version C):

Pitch: -5   -5    -5        0     7        5     4     2    12    7
Dur:   T8th  T8th  T8th  /  half  half  /  T8th  T8th  T8th half  quarter

Or, leaving out the pickups as I originally did (version B):

Pitch: 0     7        5     4     2    12    7
Dur:   half  half  /  T8th  T8th  T8th half  quarter

My original, inaccurate version was (version A):

Pitch: 0        7     5     4     2        12       7
Dur:   quarter  half  T8th  T8th  T8th  /  quarter  half

NB: "T8th" = triplet 8th; "/" = barline.

(2) Also, with the loop written this way, there's no need for the <onFirstNote>
variable; get rid of it. For extra credit, do (3) and (4) below. NB: if you do version
C, the repeated notes at the beginning will blend into a single longer note unless you
do steps (3) and/or (4) below, but don't worry about it.


* MUSIC INFORMATICS MAJORS:

In addition to the above, modify the program to (3) add a bit of silence after every
note, and to (4) get rid of the clicks at the beginning and end of every note; by far
the easiest way is with a quick fade in and fade out. Both changes should make the
performance slightly less ugly. If that's not enough to keep you busy, for extra credit,
also (5) add dynamics -- or substitute an actual musical instrument sample for the sine
wave. (You can download free musical instrument samples from the University of Iowa; my
"Information Sources for Music Informatics Students" page gives the link.)

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GRADING RUBRIC

Of course it's important that a program do what it's supposed to do, but things aren't as
simple as that. It's also important that the code be as straightforward and as easy to
understand as possible, (1) because it's amazingly difficult to be sure a program of any
complexity will always work by testing it, and (2) because many programs turn out to be
useful long after they're written, either as is or, very often, with modifications.
Starting with a program that wasn't clearly written in the first place greatly increases
the chance of modifications introducing bugs. See the slides on programming (starting
with no. 13) in the "R Programming and Digital Audio" slide show.

A work: your changes to the program are straightforward and easy to understand. For
Music Informatics majors,  it does steps (1) thru (4) correctly; for others, it does
steps (1) and (2) correctly.

B work: either your changes are hard to understand or the program fails to do one
required step correctly.

C work: your changes are hard to understand _and_ the program fails to do one required
step correctly, or your changes are easy to understand but it fails to do two required
steps correctly.