SI204 Spring 2010

Programming Project 1

Audio Speed Dial


 

Pre-Coding Analysis: Due at start of class on Monday, 1 February 2010. Turn in a flowchart or pseudocode (either neatly hand-drawn or using a drawing/text  tool) for a Step 3 solution for the program in Project 1. Make sure that your flowchart/pseudcode clearly shows how you intend to solve the conceptually difficult parts of the project.  Note that you DO NOT have to actually code up the solution as part of the Pre-Coding Analysis. This “Step 0” analysis is worth 5 points of your final project grade.

1.      Note that this Pre-Coding Analysis is NOT a routine out-of-class assignment, but rather is part of the project and therefore subject to the Department's policy concerning programming projects.

2.        Recall that the Department’s policy states that for a programming project “midshipmen may give no assistance whatsoever to any person and may receive no assistance whatsoever from any person other than the midshipman’s instructor for the course assigning the project.” Please view http://www.usna.edu/CS/academics/ProgrammingPolicy.pdf for additional details on this issue.

Executive Summary

Touch-tone dialing is used to signal a number to connect to the call switching center.  It is a trademarked form of dual-tone multi-frequency signaling that is in the voice-frequency band.  Every time a key is pressed on a touch tone phone, two distinct frequencies are transmitted from the phone to the call switching center.  The switching center then determines the number pressed from the two tones.  The consequence of this system is that you do not have to press a key to make a call if you can generate the tones required.

For this project, you will write a program that creates a sound wave (as a .wav file) that plays a telephone number.  By holding the telephone up to your computer speakers, playing the file will dial a number on your telephone.  (Caveat: cordless phones don’t give you the direct access you need – test with a corded phone instead!)


Due Dates and Honor

 

            The Pre-Coding Analysis will be due in class on Mon Feb 1 2010.

 

This project will be due by the close of business on Thursday Feb 11, 2010.  See the course policy for details about due dates and late penalties.

Again, this is a Programming Project, and it is very important that you understand and abide by the Department's policy concerning programming projects. Please view: http://www.usna.edu/CS/academics/ProgrammingPolicy.pdf 

Extra Information

 

1.      Sound and wave files

 

What our ears perceives as sound is simply a wave moving through the air that vibrates our eardrums.  This wave propagates by the compression and rarefaction of the atmosphere (Figure 1).  This change in air density at a single point can be graphed with respect to time (Figure 2)  This change in air density over time is the data that describes any sound wave and is encoded in a wave file.

 

Figure 1

Figure 2

 

A wave file is data consisting of two parts: a header chunk that describes the amount of information that it contains and a data chunk that contains numbers that correspond to sound amplitudes (or air pressure) over time.  This data chunk is exactly what is encoded on a compact disc.  The header portion is not required for CDs because the encoding options are fixed. To understand the files you will be creating, you need to understand the options for encoding a wave file.

 

The header chunk contains the following pieces of information (among others):

 

sample rate: samples per second

bits per channel: 8 or 16

number of channels: mono or stereo

 

Channels should be self-explanatory.  Sample rate and bits per channel are necessary because computers can only handle discrete numbers.  In the real world, waves are continuous but computers need to approximate to represent continuous numbers.  This is shown below.

 

 

In order to represent a continuous wave, the computer will connect a series of points that are close to the original waveform.    The red, smooth line represents the original waveform.  The black, jagged line represents the waveform played by the computer.  This example shows 4 bits per channel (24=16 levels) and a sample taken every 0.1 seconds.  This means the sample rate is 10 Hz (=1/0.1 seconds). 

 

 We will use mono (1 channel) 8-bit encoding at a sample rate of 8000 Hz.

 


 

2. Useful data

 

A basic sine wave is described by the following formula:

            y(t) = Amplitude * sin (2 * π * frequency_in_Hertz * t)

where y(t) is the value of the waveform at time t (t is measured in seconds).

 

The tone for a single telephone digit is created by adding together two sine waves at different frequencies.  For instance, a ‘1’ is made by adding sine waves of frequency 697 Hz and 1209 Hz.  So the sound for a ‘1’ is described by this formula:

            y(t) = Amplitude * sin (2 * π * 697 * t) + Amplitude * sin (2 * π * 1209 * t)

 

The table below shows the other frequency combinations:

 

Hz

1209

1336

1477

697

1

2

3

770

4

5

6

852

7

8

9

941

*

0

#

Touchtone Frequencies

  

3. Useful code

 

A Visual Studio “project” with some needed code is provided: starter.zip. Download this and unzip it somewhere (your X: drive would be ideal – if you haven’t already, set up access to that from Bancroft; see the course home page for help). Then from Visual Studio, choose “Open Project” and browse to and open “Project1.sln.”

 

A file project1.cpp is provided – this is the only file you should change and submit!  (i.e. do not modify other .cpp or .h files). Along with the standard stuff, this file has some starter code for you.  At the top, to provide access to the code that will generate sound files for you, is this:

 

#include "Wave.h"

 

Then in main() is the following code. Start your code after this:

 

WaveFile out;                        //creates WaveFile object named out
string fileName = "frequency.wav";   //creates variable to hold wave file name
bool success = out.OpenWrite(fileName.c_str()); //link ‘out’ object to filename

       if (success == false)

       {

          cout << "Failed to open output file " << fileName << endl;

          cout << "Close other applications using the file and try again." << endl;

          return 0;

       }

out.SetupFormat(8000,8,1);           //sampleRate = 8000 Hz
                                     //bitsPerSample = 8, channels = mono

 

Whenever you have a number y that you want to write to the wave file use the statement:

out.WriteSample(y);

y must be a continuous number between -1 and 1.  You also must output y to the screen.  This will aid your debugging, but you will only see the last few samples on the screen.  See the sample output below for an example.

 

Note: if you make a statement such as

out.WriteSample(0.5)

you may receive a compile error regarding “ambiguous overloaded function.” This will make sense later – for now, instead always use a variable (such as y) instead of a constant (such as the literal 0.5) when you use WriteSample.

 

Also, the constant PI has been provided for you. You can use it just like a variable, e.g.

area = 2 * PI * radius * radius;

 

 

Details

The project is divided up into four steps. You are strongly encouraged to solve each step completely - including thorough testing - before you move on to the next step. You must submit each step on Blackboard after you complete it (see details later).

 

Also, remember that your program’s source code must comply with the Required Style Guide in order to maximize the grade you receive on this project.  Compile your program often so you don’t end up with a snake’s nest of errors at your first compile, and occasionally save a backup copy of your program’s source code in case your sponsor’s dog eats your X drive.

 

Step 1: Create a waveform from a user frequency and write it to a wave file

Write a program that reads in a frequency (in Hz) from a user and creates a wave file named frequency.wav with the corresponding waveform. This waveform should have an amplitude = 0.5 and a length of 1 second.  Sample output is shown below.

 

If your sample output looks reasonable (try 800 Hz), try playing the sound by double-clicking on the .wav file (it will be in the same directory as your .cpp file). This will run Windows Media Player or a similar player.  You should be able to hear a 800 Hz tone.

 

Key tip #1: If your program doesn’t stop running, click on the output window, then press Ctrl-C to kill it.

Key tip #2: You MUST close Windows Media Player after you play your sound.

Key tip #3: Your output may not exactly match the sample output shown below.  How can you tell though if it is truly outputting a 800 Hz wave? (think about the period of the wave)

Key tip #4: Until you get to step 4, you should need no more than 40 lines of code (at most).  Otherwise, you’re probably not on the right track.

Key tip #5: Save a complete copy of each step when it works before you go on to the next step.

Key tip #6: If you’re not sure why your program doesn’t work, add additional “cout” statements to test the values of variables at different points in your program (or just to see how far your program is getting).

 

 

 

Step 2: Create a waveform from a user frequency and amplitude and write it to a wave file

Write a program that reads in a frequency and amplitude from the user and creates a wave file named amplitude.wav with the corresponding waveform.  See sample output for expected values.  Check that the amplitude provided by the user is between 0 and 0.5.  If it is outside this range, set it to 0.5.

 

 


Step 3: Create a wave file that dials a single button

Write a program that creates a file named star.wav that dials the star key.  It should still get the user input for the amplitude and be one second in length.  Check that the amplitude is between 0 and 0.5.  If it is outside this range, set it to 0.5. It should sound like your phone when the star key is pressed.  Here’s a sample with amplitude 0.5:

 

 Step 4: Create a wave file that dials a five digit extension

Write a program that creates a single wave file named dial.wav that dials a phone number provided by the user. In particular, the user will enter any number of digits (or # or * symbols), terminated by an X.

 

Use the frequencies given above to make a dual tone waveform for each number (0.1 seconds for each) separating each number by 0.1 seconds of silence (how do you think silence should be produced?) It should still get the user input for the amplitude.  Check that the amplitude is between 0 and 0.5.  If it is outside this range, set it to 0.5. 

 

You can stop outputting each “y” value to the screen now. Instead, output the frequencies that you are using for each tone.

 

Once you think it is working, hold your phone up to the speakers on your computer and play the sound!  Try calling 30123 (voicemail) or some other number you like.  Remember that you probably need a corded (NOT cordless) phone for this to work.  If you really can’t get a corded phone, compare your sound with the 30123.wav file provided on the course calendar. You can also use the 30123.wav file to test out how the “audio” dialing should work.

 

Tip #1: Your program should work for any number of digits! (not just 5). Think first about how you will handle this.

Tip #2: Don’t forget to save a complete copy of Step 3 before you start this!

  


What to submit and how it will be graded

You will only submit a solution to one of the four steps above. You will submit your solution for the highest numbered step that actually works! For example, if you had a working solution to Step 3, but only a partially completed solution to Step 4, you would submit your Step 3 solution.

 

The maximum points for a Step 0 solution is 5 pts, for a Step 1 solution, 30, for a Step 2 solution, 50, for a step 3 solution, 70, and for a Step 4 solution, 100 pts. How points are assigned for a particular solution is at your instructor's discretion, however, program structure, documentation, variable names, etc. will be considered along with program correctness. Important points:

·         If your program does not compile as submitted, you will receive a zero.

·         If your program does not give correct results, penalties will be substantial. If you can't get a working Step k+1 solution, submit your Step k solution instead.

·         Your program must read input and write output in the exact format specified in this project description.

·         Your program’s source code must comply with the Required Style Guide in order to maximize the grade you receive on this project

There will be both a paper and an electronic part to your submissions. The paper submission can be handed to your instructor in class or slid under their office door (do NOT put it in their mailbox or outside their door). For the purposes of any late penalties, your project is not considered submitted until your instructor receives BOTH the electronic and paper portions of your submission.

Reminder -- You MUST submit (via Blacboard) a working solution for EACH of the above steps as you complete them.   Submit just the project1.cpp file. It’s okay if you make some changes to a step after you submit it, but we want to see the progression of your steps. The individual steps will not be graded for style or functionality – as long as it looks reasonably like you submitted the steps, what counts will be the style and functionality of the final result (submit on Blackboard as such).

Electronic submission: Unless otherwise specified by your instructor, electronic submission should be made via Blackboard. You will submit only your project1.cpp file (the other files should not be changed). Submit each step as you complete it, then when all finished submit your final project1.cpp file under the “Final Submission” link (regardless of how many steps you completed).

 Here's what to submit  (follow instructions for one of the following):

Step 0 Pre-coding Analysis: (5 pts). See description at start of project.

Step 1 submission: (max 30 pts)

Paper: Submit a printout of your source code and a screen capture showing your program being run on input 800. You will also submit a signed copy of the project cover page (see SI204 home page).
Electronic: See above. 

 

Step 2 submission: (max 50 pts)

Paper: Submit a printout of your source code and a screen capture showing your program being run on input 800 and 1.5. You will also submit a signed copy of the project cover page (see SI204 home page).
Electronic: See above.

 

Step 3 submission: (max 70 pts)

Paper: Submit a printout of your source code and a screen capture showing your program being run on input 1.5.  You will also submit a signed copy of the project cover page (see SI204 home page) .

Electronic: See above.

 

Step 4 submission: (max 100 pts)

Paper: Submit a printout of your source code, a screen capture showing your program being run on input 30123X. You will also submit a signed copy of the project cover page (see SI204 home page).
Electronic: See above.

 

Extra Credit #1: (Maximum of 5 points) Add a “pause” capability to your program, so that a “number” entered of P causes the sound to pause with silence for an extra 0.1 seconds. Thus, I should be able to “dial” the number 30123PP36811#X.

 

Extra Credit #2: (Maximum of 5 points) Submit a separate program that first reads a name from the user, then reads phone numbers from a file that looks like this:

            John    36811X

            Sally    4105551212

            Mail      30123X

Find the phone number that matches the name and output the dialing waveform for that number to an appropriately named file. Then ask the user if they want to do any more names and repeat if so.