CS 312 - Week 1.2
CS 312 Audio Programming Winter 2020

There were some issues in class 1.1 with the WCC setup. I've written the link below to explain in detail the scripts I created to setup the WCC lab environment for CS312. I'm unable to directly test your student accounts in WCC so I need your help in validating my approach.

Open and the link below and follow the directions.
Notify me if things you see are different from what I've written.

WCC startup.html

Continue with the Lab 1.2 section for this class.

Written by John Ellinger for CS312. You'll have the skills to write this by the end of the term. DLS refers to DownLoadable Sounds, a sample sound format that can be used in Audio plugins. Apple licensed a General MIDI sound set from Roland Corporation to use in its built in MIDI synthesizer.

I did not write this app with the degree of error checking and reporting necessary for a commercial program. It was designed a a tool for experimenting with MIDI messages in the Carleton Music Technology classes I've taught in the past. Feel free to send me an email or talk to me in class if you discover a reproducible error. Reproducible means you can write down the steps that produce the error.

Open MIDIDisplay_DLS

Time Base

Leave at default Chronological Ms.

MIDI Inputs

Leave at default IAC Driver Bus 1.

MIDI Outputs

Leave at default IAC Driver Bus 1.

PPQ menu

Leave at default 480.

Tempo Slider

Changes the tempo (playback speed). Tempo changes are accurate only if the timestamp data was entered based on a tempo of 60 bpm.

Test Button

Non functional at this time. Will crash.

Record Button

Non functional unless a MIDI keyboard is connected and setup properly for Mac OS.

Play Button

Plays the MIDI messages in the window.

Stop Button

Sends a NOF message to notes 0-127 on all 16 MIDI channels. This command takes about four seconds to complete. The delay happens because MIDI can only send a a certain number of messages per millisecond. Sending all the messages at once could cause a "MIDI log jam."

Data Entry Area

The main window area is a text editor where you can enter MIDI data. It responds to the usual text editing commands.

Status Header

The status header above the Data Entry Area reminds you that each MIDI message must be entered in a specific number base. The status number is a hex value but is not prefixed by 0x. Data2 is in parentheses because some MIDI messages do not use it.

time	status	data1	(data2)
decimal	hex	decimal	decimal

Conventions

1. The MIDIDisplay_DLS data entry tempo is always 60 beats per minute.
   
2. Rows beginning with a # are comments and will be ignored.
   
3. One quarter note beat is 1000 milliseconds.
   
4. MIDIDisplay_DLS does minimal error checking and expects your data to be error free.

Delete all text from MIDIDisplay_DLS.

Recompile hw112_helloMidi.cpp in Mac Terminal.

cd $HOME312/cs312/hw11
cl hw112_hellomidi.cpp
# Copy the output of a.out to the clipboard
./a.out | pbcoppy

Switch to MIDIDisplay_DLS and immediately paste. It should work.

Notes:

pbcopy, pbpaste

Apple commands for copying and pasting. pb refers to pasteboard an internal buffer that holds the text copied.

|

the pipe operator. The output of the command on the left becomes the input to the command on the right.

The following examples are meant to demonstrate using MIDI messages to modify the six properties of sound. Copy/replace/paste each example into MIDIDIsplay_DLS and play it.

# Reset all controllers to default state
0  B0  121 0
#
0  C0  0
0  90  60  100
0  90  64  100
0  90  67  100
0  90  72  100
#
2000  80  60  0
2000  80  64  0
2000  80  67  0
2000  80  69  0

This example uses two MIDI channels out of a total of 16 available. Channel 10 (zero based 9) is reserved for drums. Channel 1 (zero based 0) is flute and channel 2 (zero based 1) is bassoon.

# Reset all controllers to default state
0  B0  121 0
#
0  C0  73
0  C1  70
#
0	90	67	100
0	91	55	100
#
900	80	67	0
900	81	55	0
#
1000	90	69	100
1000	91	53	100
#
1900	80	69	0
1900	81	53	0
#
2000	90	71	100
2000	91	50	100
#
2900	80	71	0
2900	81	50	0
#
3000	90	72	100
3000	91	48	100
#
3900	80	72	0
3900	81	48	0

Quit MIDI Display_DLS

If you still have time in class continue to the Homework section and start with vsCode settings.

The MIDI Specification appeared in 1983 as a music industry hardware/software standard that allowed MIDI hardware devices made by different manufacturers (Roland, Yamaha, Korg …) to communicate directly with each other as well as communicate with different PC operating systems (DOS, Windows, Mac, Linux…). MIDI version 1 has been around for 37 years. In 2019 the MIDI version 2 specification was announced but hardware and software have yet to appear. It will be backward compatible with MIDI version 1.

My first computer was a Mac Plus that I purchased one week after it was introduced in 1986. Within a year I had written my first MIDI program. Two years later I was selling my first commercial MIDI program for jazz improvisiation on the Mac. It was written in Pascal, the language of the Mac operating system in those days.

This Class 1.2 page, especially the MIDI and Mac Finder sections.

TCPP2
char § 1.4
Template § 6.1, 6.2
static_cast p. 53
formatting § 10.6
bitset § 13.4.2

Choose Command Palette from the View menu.
Shortcut: Command-Shift-P

Enter settings in the search bar and then select /Preferences: Open Settings (JSON)

Note

If the settings.json window that opens is empty copy/paste the code below.
If the settings.json window already contains code between curly braces leave it there and append the statements between the curly braces just above the closing curly brace.

{
    "editor.multiCursorModifier": "ctrlCmd",
    "editor.formatOnPaste": true,
    "editor.formatOnSave": true,
    "editor.fontSize": 14,
    "window.zoomLevel": 0,
    "terminal.integrated.shell.osx": "/bin/bash",
    "terminal.integrated.fontSize": 14,
    "terminal.integrated.scrollback": 32000,
    "C_Cpp.clang_format_style": "Visual Studio",
    "C_Cpp.clang_format_path": "/usr/local/bin/clang-format",
    "terminal.integrated.cursorStyle": "line",
    "editor.tabSize": 2,
    "editor.insertSpaces": false,
    "[cpp]": {},
    "editor.defaultFormatter": "ms-vscode.cpptools",
    "clang-format.executable": "/usr/local/bin/clang-format",
    "clang-format.language.cpp.fallbackStyle": "LLVM",
    "clang-format.fallbackStyle": "LLVM",
    "window.restoreWindows": "none",
    "editor.minimap.enabled": false
}

First we'll turn your boilerplate executable into a command line tool.

Recompile hw111_boilerplate.cpp with this command.

cd $HOME312/cs312/hw11
cl hw111_boilerplate.cpp -o boilerplate
./boilerplate

You should see the output of boilerplate in the terminal.

Move boilerplate into the $HOME312/bin directory.

mv boilerplate $HOME312/bin/

Execute the boilerplate command.

boilerplate

You should see the text appear. This works because $HOME312/bin has been added to the $PATH environment variable.

Create the hw12 folders and files Execute these commands in Terminal.
You can copy the entire contents and paste into Terminal.

cd $HOME312/cs312
mkdir hw12
cd hw12
touch hw121_charOutput.cpp
touch hw122_charOutputTemplate.cpp
touch hw123_charLoop.cpp
touch hw124_asciiTool.cpp
touch hw125_printMajorScale.cpp
code . # . refers to the current directory, in this case

Vscode should open the $HOME312/cs312/hw12 directory with the five source files displayed on the left.

Now try this in Terminal

boilerplate | pbcopy
pbpaste >> hw121_charOutput.cpp

Open hw12_charOutput.cpp in vsCode and you should see your boilerplate text appear.
Edit the filename and the assignment lines.
The date and time should be current.
If the file on the right of >> doesn't exist it will be created.

You can use this method to add boilerplate to the other four homework files.

Notes:

>>

the redirection operator. \ The output of the command on the left (must be text) is redirected to the file on the right.
A double angle >> appends the text at the end of the file.
A single angle > deletes the content of the file before appending.
Be careful when you use the single angle for redirection.

pbcopy, pbpaste

Apple commands for copying and pasting.
pb refers to pasteboard, an internal buffer that holds the copied text.

|

the pipe operator.
The output of the command on the left becomes the input to the command on the right.

Modify the program to display the actual number assigned to the three variables. You must keep the type char. You want the program to display the output shown below.

Question: Why did this happen?
Append a block comment at the end of your source code and explain.

Implement the template void print(T x, std::string msg) to display each char type as:

• decimal
• hexadecimal
• hexadecimal with 0x prefix
• binary

#include <iostream>
#include <string>
#include <bitset>

template <typename T>
void print(T x, std::string msg) {
 // you write
 }

int main() {
  char c = 9;
  signed char sc = 250;
  unsigned char uc = 144;

  print(c, "c: = ");
  print(sc, "sc: = ");
  print(uc, "uc: = ");
}

Hint: I used these.

• static_cast<type>(value)
• std::hex
• std::dec
• std::showbase
• std::noshowbase
• std::bitset<8>

The reading assignment above and Google will help. Use Google to figure out what std libraries to include for the above statements.

Why use a template
The reason is to avoid writing three separate functions that would all use the same code in the function body.

void print(char x, std::string msg);
void print(signed char x, std::string msg);
void print(unsigned char x, std::string msg);

Compile and run
You'll get a compiler warning but you'll still get output.

warning: implicit conversion from 'int'
     to 'signed char' changes value from 250 to -6 [-Wconstant-conversion]
 signed char sc = 250;

Output

c: = 9
c: = 9
c: = 0x9
c: = 00001001

sc: = -6
sc: = fffffffa
sc: = 0xfffffffa
sc: = 11111010

uc: = 144
uc: = 90
uc: = 0x90
uc: = 10010000

Warnings are good but they need to be fixed.
Fix the error by changing the signed char value to 50.

Output

c: = 9
c: = 9
c: = 0x9
c: = 00001001

sc: = 50
sc: = 32
sc: = 0x32
sc: = 00110010

uc: = 144
uc: = 90
uc: = 0x90
uc: = 10010000

When you use a plain char type to represent numbers there is no range checking. Using signed char and unsigned char incorrectly will issue a warning when you compile the program but it will still run. You should make it a habit to fix compiler warnings.

Fix it.

Output when fixed

0 =
1 =
2 =
3 =
4 =
5 =
6 =
7 =
8 =
9 =
10 =

11 =

12 =

13 =
14 =
15 =
16 =
17 =
18 =
19 =
20 =
21 =
22 =
23 =
24 =
25 =
26 =
27 =
8 =
29 =
30 =
31 =
32 =
33 = !
34 = "
35 = #
36 = $
37 = %
38 = &
39 = '
40 = (
41 = )
42 = *
43 = +
44 = ,
45 = -
46 = .
47 = /
48 = 0
49 = 1
50 = 2
51 = 3
52 = 4
53 = 5
54 = 6
55 = 7
56 = 8
57 = 9
58 = :
59 = ;
60 = <
61 = =
62 = >
63 = ?
64 = @
65 = A
66 = B
67 = C
68 = D
69 = E
70 = F
71 = G
72 = H
73 = I
74 = J
75 = K
76 = L
77 = M
78 = N
79 = O
80 = P
81 = Q
82 = R
83 = S
84 = T
85 = U
86 = V
87 = W
88 = X
89 = Y
90 = Z
91 = [
92 = \
93 = ]
94 = ^
95 = _
96 = `
97 = a
98 = b
99 = c
100 = d
101 = e
102 = f
103 = g
104 = h
105 = i
106 = j
107 = k
108 = l
109 = m
110 = n
111 = o
112 = p
113 = q
114 = r
115 = s
116 = t
117 = u
118 = v
119 = w
120 = x
121 = y
122 = z
123 = {
124 = |
125 = }
126 = ~
127 =

Question: What caused the infinite loop?/
Append your answer in a block comment at the end of your source code.

Paste your corrected code from hw123_charLoop.cpp into hw124_asciiTool.cpp. Then modify it to produce the ASCII chart shown below. The chart displays the decimal value, hexadecimal value, and printed character for each ascii character 0-127.

Compile using this command to save the ascii tool directly to your ~/bin folder

cl hw124_asciiTool.cpp -o $HOME312/bin/ascii

Test it Execute

ascii

Output

0 (0) = 
1 (0x1) = 

2 (0x2) = 
3 (0x3) = 
4 (0x4) = 
5 (0x5) = 
6 (0x6) = 
7 (0x7) = 
8 (0x8) = 
9 (0x9) =
10 (0xa) =

11 (0xb) = 
12 (0xc) = 
13 (0xd) =
14 (0xe) = 
15 (0xf) = 
16 (0x10) = 
17 (0x11) = 
18 (0x12) = 
19 (0x13) = 
20 (0x14) = 
21 (0x15) = 
22 (0x16) = 
23 (0x17) = 
24 (0x18) = 
25 (0x19) = 
26 (0x1a) = 
27 (0x1b) = 
28 (0x1c) = 
29 (0x1d) = 
30 (0x1e) = 
31 (0x1f) = 
32 (0x20) =
33 (0x21) = !
34 (0x22) = "
35 (0x23) = #
36 (0x24) = $
37 (0x25) = %
38 (0x26) = &
39 (0x27) = '
40 (0x28) = (
41 (0x29) = )
42 (0x2a) = *
43 (0x2b) = +
44 (0x2c) = ,
45 (0x2d) = -
46 (0x2e) = .
47 (0x2f) = /
48 (0x30) = 0
49 (0x31) = 1
50 (0x32) = 2
51 (0x33) = 3
52 (0x34) = 4
53 (0x35) = 5
54 (0x36) = 6
55 (0x37) = 7
56 (0x38) = 8
57 (0x39) = 9
58 (0x3a) = :
59 (0x3b) = ;
60 (0x3c) = <
61 (0x3d) = =
62 (0x3e) = >
63 (0x3f) = ?
64 (0x40) = @
65 (0x41) = A
66 (0x42) = B
67 (0x43) = C
68 (0x44) = D
69 (0x45) = E
70 (0x46) = F
71 (0x47) = G
72 (0x48) = H
73 (0x49) = I
74 (0x4a) = J
75 (0x4b) = K
76 (0x4c) = L
77 (0x4d) = M
78 (0x4e) = N
79 (0x4f) = O
80 (0x50) = P
81 (0x51) = Q
82 (0x52) = R
83 (0x53) = S
84 (0x54) = T
85 (0x55) = U
86 (0x56) = V
87 (0x57) = W
88 (0x58) = X
89 (0x59) = Y
90 (0x5a) = Z
91 (0x5b) = [
92 (0x5c) = \
93 (0x5d) = ]
94 (0x5e) = ^
95 (0x5f) = _
96 (0x60) = `
97 (0x61) = a
98 (0x62) = b
99 (0x63) = c
100 (0x64) = d
101 (0x65) = e
102 (0x66) = f
103 (0x67) = g
104 (0x68) = h
105 (0x69) = i
106 (0x6a) = j
107 (0x6b) = k
108 (0x6c) = l
109 (0x6d) = m
110 (0x6e) = n
111 (0x6f) = o
112 (0x70) = p
113 (0x71) = q
114 (0x72) = r
115 (0x73) = s
116 (0x74) = t
117 (0x75) = u
118 (0x76) = v
119 (0x77) = w
120 (0x78) = x
121 (0x79) = y
122 (0x7a) = z
123 (0x7b) = {
124 (0x7c) = |
125 (0x7d) = }
126 (0x7e) = ~
127 (0x7f) = 

Question: Why is the ASCII chart is discontinuous at numbers 10, 11, 12, and 27?
Append a block comment at the end of your source code to explain why.
Add your boilerplate header and turn in as asciiTool_124.cpp

When your compile succeeds try these examples in a Terminal

ascii | grep A

Output is not what's expected.

Binary file (standard input) matches

From man grep

Normally grep will simply print
``Binary file ... matches'' if files contain binary characters.

Also from man grep describing the -a or --text option

Treat all files as ASCII text...Use of this option forces grep
to output lines matching the specified pattern

Search for ascii value of A

ascii | grep --text
ascii | grep -a A

65 (0x41) = A
65 (0x41) = A

Search for ascii value a.

ascii | grep -a a

grep found every a in the file

10  (0xa)  =
26  (0x1a)  =
42  (0x2a)  =  *
58  (0x3a)  =  :
74  (0x4a)  =  J
90  (0x5a)  =  Z
97  (0x61)  =  a
106  (0x6a)  =  j
122  (0x7a)  =  z

Searching for <space>a or <space>A will work. The -i flag is case insensitive.

ascii | grep -ai " a"

65  (0x41)  =  A
97  (0x61)  =  a

ascii | grep -a 0

0 (0) =
1 (0x1) =
2 (0x2) =
3 (0x3) =
...
127 (0x7f) =

ascii | grep -a "= 0"

48 (0x30) = 0

Write a program to print the notes in MIDIDisplay_DLS format needed to play a major scale on any starting note. Then test your output in MIDIDisplay to verify that it works. Here's the outline of the program.

#include <iostream>

void print_major_scale( int start_note) {
  // you write
}

int main() {
  // whatever's needed
  int note = 60; // starting pitch
  print_major_scale( note );
}

Rules

timestamp

every NON (note on) is separated by 500 ms
every NOF (note off) timestamp occurs 400 ms after its corresponding NON

status (hex value without 0x)

use 90 for the NON status byte
use 80 for the note off NOF status byte

data1 (decimal value)

The pattern for the major scale starting at note zero is: 0, 2, 4, 5, 7, 9, 11, 12.
The same pattern could be expressed as: 0, 2, 2, 1, 2, 2, 2, 1 where those numbers were understood to be the differences between adjacent numbers in the pattern above.
If you add these offsets to any starting note it will form a major scale.

data2 (decimal value)

use 100 for all NON velocities
use 0 for all NOF velocities

NON and NOF pairs

every note on (NON) message MUST be followed by a matching note off (NOF).

Example
If you wanted to play a major scale starting on MIDI note number 60 (middle C) the notes (data1) used would be:

# using offsets from starting note 0 2 4 5 7 9 11 12
60 + 0 = 60
60 + 2 = 62
60 + 4 = 64
60 + 5 = 65
60 + 7 = 67
60 + 9 = 69
60 + 11 = 71
60 + 12 = 72
# using adjacent differences after starting note 2 2 1 2 2 2 1
60 = 60 # starting note
60 + 2 = 62
62 + 2 = 64
64 + 1 = 65
65 + 2 = 67
67 + 2 = 69
69 + 2 = 71
71 + 1 = 72

Here's the beginning of the correct output.

0       90      60      100
400     80      60      0
500     90      62      100
900     80      62      0
1000    90      64      100
1400    80      64      0

Test it in MIDIDisplay_DLS to make sure it works.