CS 101 - Introduction to Computing, Fall 2008

Lab 12

In this lab, you will take a single sound file and have it fade in (increase) from silence to full volume and then fade out (decrease) into silence again. Program 71 from the book will be a very helpful method to use in this lab! You can find sample soundtrack files to use for this lab here.

Also, this code might help you out as well.

Think about what happens when you are increasing the volume of a sound. Say I have a sound of length 10 samples. At the end of the sound I want to have full volume, yet at the beginning I want to have silence. I can do this by first finding the interval between the samples. That means that I can break my sound into 10 sections, where on each section I increase my volume by an additional 10%. By the time I have reached the end of the song, I will have been at full volume. Note that is is different than what was done during class with example Lect1113a.java.

I will do the same for when I decrease a sound, only this time it is the reverse.

You may have to use doubles when you step up to the next interval. Because you will increase each sample by a percentage, you will have to use a double. However, you may recast this value to an int when you set the SampleValue in the new sound file.

The result will be a file that increases in "steps", but for the purposes of this exercise this is OK. Hopefully you will not notice it!

This lab will require three methods. The first method will take in the first half of the sound and increase the volume from silence to 100%. The second method will take in the second half of the sound and decrease the volume from 100% to silence. Finally, a third method will put these two parts back together again.

• Method 1: increase():
  
  • this method will be given in the first half of the sound as a parameter
    
  • divide the sound into 10 equal length sections
    
  • set the first section to 1/10th of its volume
    
  • set the second section to 2/10ths of its volume
    
  • continue until the ninth section is set to 9/10ths of its volume
    
  • the tenth section is set to 10/10ths of its volume (i.e. left unmodified)
    
  • and return the modified sound.
    

• Method 2: decrease():
  
  • this method will be given in the second half of the sound as a parameter
    
  • divide the sound into 10 equal length sections
    
  • set the first section to 10/10th of its volume (i.e. left unmodified)
    
  • set the second section to 9/10ths of its volume
    
  • continue until the ninth section is set to 2/10ths of its volume
    
  • the tenth section is set to 1/10th of its volume
    
  • and return the modified sound.
    

• Method 3: joinSounds():
  
  • this method will take two sounds as its parameters
  • create a new sound whose length is equal to the length of the two sounds added together
  • join the two sounds so that the first sound is in the beginning of the new sounds and the second sound is at the end of the new sound.
  • return the joined sound

You should also have code to save the sound on the hard drive.

Lab Assignment 12

Create a Java program that will:

1. Contain a comment indicating
   • your Name,
   • Net-ID,
   • Course Name,
   • Assignment Name and
   • a short description of the assignment

2. Contain the main() method that will
   • Prompt the user for a soundtrack file
   • Split this file into two parts of equal length
   • Send the first part to the increase() method, and return
   • Send the second part to the decrease() method, and return
   • Send these two parts to the joinSounds() method, and return
   • Play (or explore) the sound.
   • Prompt the user for a name and save it.

• Sample Sound File

Submittal of the Lab Assignment

• When saving your program, use a meaningful name like Lab12.java.
• You are also to submit the Java file electronically by using the UNIX turnin command.
• You do no have to submit the sound file, as the CS servers might run out of space. :(

  To use the UNIX turnin command to electronically hand-in your html file using the project name of lab12. To submit the file Lab12.java for lab12, the turnin command is entered as:

       turnin -c cs101 -p lab12 Lab12.java 
  

  To verify what you submitted using the turnin command type:

       turnin -c cs101 -p lab12 -v