Lab 1: Wav Files

Resources Needed

• If you need to install Java, please follow these instructions.
• Accept the GitHub Classroom assignment invitation in Canvas and then, in IntelliJ, create a new project from Version Control using the repository URL. If you haven't used this before, see the pre-lab activity that was part of CS1011 Lab 6.
• WavFile Documentation

Overview

In this assignment you will make use of the WavFile class to read and write .wav audio files.

• Video introducing the lab assignment
• How speakers work

Details

ArrayList Requirement

This assignment is meant as a review of material covered in CS1011. You are required to use at least one ArrayList object.

Using a Supplied Class

For this assignment, you will need to make use of the WavFile class (javadoc). You may not change the package for the WavFile class. You must place it in the appropriate folder within your project.

Basic Program Flow

You'll need to create one class called WavGenerator which should be in a package named the same as your MSOE username (e.g., taylor). Note: Do not place all of the functionality for your program in main. Prior to coding, decide on how you plan to encapsulate functionality into multiple methods. This class must contain your program that makes use of the WavFile class to do the following:

• Ask the user to enter 0, 1, 2, or 3. If the user enters anything other than one of those four options, the program should reprompt the user to enter one of the four options (it should continue to do this forever).
• If the user enters 0, the program should exit.
• If the user enters 1, the program should prompt the user to enter a filename (without the .wav extension) and then read the file in and write a separate .wav file with all of the audio samples placed in reverse order. For example, if the user enters cymbal, the output file should be called cymbalRev.wav. Once this has been completed, the program should return to the prompt which asks the user to enter 0, 1, 2, or 3.
• If the user enters 2, then the program should ask the user for a filename (without an extension) and a frequency. The program should then create a .wav file containing one second worth of audio that represents a tone at the specified frequency. Once this has been completed, the program should return to the prompt which asks the user to enter 0, 1, 2, or 3.
• Optional: If the user enters 3, then the program should ask the user for a filename (without an extension) and two frequencies. The program should then create a .wav file containing one second worth of audio in stereo. One frequency should be on one channel and the other frequency on the other channel. Once this has been completed, the program should return to the prompt which asks the user to enter 0, 1, 2, or 3.

Note: Your program must not crash on menu selection regardless of what the user enters for a menu option.

Hints

• To generate one second of audio, make sure that the numFrames and the sampleRate contain the same value.
• You may use cymbal.wav and ominous.wav as sample .wav files. You may wish to use the WavFile.toString() method to determine appropriate values to pass the multi-argument WavFile constructor. There are some additional .wav files in the sounds folder for those interested.
• To access the sound files you will need to add the sounds folder to the filename, e.g., "sounds/cymbal.wav".
• To generate a tone at a given frequency you should generate a sine wave with values between -1.0 and 1.0 at the specified frequency. The formula to use for this is sin(2pi x i x (freq/sampleRate)). Where i is the counter in the loop generating samples. Since the sampleRate is the number of samples per second, if you desire one second worth of sound, you'll need to generate sampleRate samples.
• For one second of single-channel audio (option 2), these numbers should work when creating the WavFile object: numChannels==1, numFrames==8000, validBits==8, and sampleRate==8000.
• To generate stereo audio you will need to set the number of channels to two and interleave the audio samples for each channel in the ArrayList of samples. Said another way, the samples for the first channel should be placed only at even indices and the samples for the second channel should be placed only at odd indices.
• Once you have placed the samples into the WavFile object, be sure to call .close() to be sure the file has been written completely.

Acknowledgment

This laboratory assignment was developed by Dr. Chris Taylor.