TWiki> CS111 Web>WebLeftBar>NotesS18>CodeS18>AssignmentsS18>Lab11S18 (2018-04-08, Main.troy)

## LAB 11

This lab will have you prompt the user for an amount to change the volume of a sound file. You are to prompt the user for a percent value using the requestInteger() function of the JES library. You are to then multiply every sample in the sound file by this percent value. The basic calculation is to first multiply the amplitude amount at each Sound Sample by the value entered by the user, then divide the result by 100. Note that if the user enters a value between 0 and 99, the volume of the sound file will be decreased. If the user enters a value greater than 100, the volume will be increased. If the user enters 100, the volume will be unchanged. Thus:

• To double the sample values of the sound, the user should enter 200 (which we interpret as a 200% modification).
• To triple the sample values of the sound, the user should enter 300 (which we interpret as a 300% modification).
• To half the sample values of the sound, the user should enter 50 (which we interpret as a 50% modification).
• To quarter the sample values of the sound, the user should enter 25 (which we interpret as a 25% modification).
Note you will want to check out the sample lect0403b.py. This code "doubles" the volume in a sound file by multiplying the value at every sample by 2.

For this assignment:

• If we want to double the volume of a sound, we multiply every sample value by 2
• If we wanted to triple the volume of a sound, we multiply every sample value by 3
• If we want to cut the volume of a sound in half, we multiple every sample value by 0.5
• To make the volume a quarter of what it originally was, we multiply every sample value y 0.25
Also, remember range of valid sample values is from -32,768 to +32,767. For this lab, you must also check to see if the sample value falls out of this range after the multiplication is done. If the sample value becomes greater than +32,767, set the value to +32,767. If the sample value becomes less -32,768, set the value to -32,768. This is simply done by use of two if statements. One of these if statements is as follows:

 ` if (amplitude > 32767) :` ` amplitude = 32767 `

Here are some sample sound files that can be used for this lab:

The function in the JES library of getSamples() will allow you to access a list of SoundSamples which will allow access to the sound. The JES library functions of: are useful for modifying the sample values.

# Because of this week's exam: Due: Friday 4/13/2018 by 11:59 pm

Create a Python program named with your net-id and the lab number (such as "ptroy4lab11.py") that will:

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

1. Contain a function named main() that will:
• Prompt the user for a sound file and make a sound object from this file.
• Prompt the user for an integer percent value that will be used to modify the volume of the sound.
• Call a function called modifySound() that will change the volume of the sound. The Sound object and the integer percent value are to be sent to this function as parameters.
• play (or explore) the resulting sound and prompt the user to save it in a file

1. Contain a function called modifySound() that will
• Take two parameters:
1. The first parameter will be a Sound object.
2. The second parameter will be an integer value.
• Modify the volume of the sound using the amount given by the second parameter. The amount is to be considered as a percent value. Thus a value of 100 keeps the volume unchanged. A value greater than 100 increased the volume, while a value between 0 and 100 lowers the volume.
• Check for and correct any "clipping" that may result from the resulting value being greater than 32,767 or less than -32,768.

### Program Submission

You are also to submit the python file electronically via the link in the assignment page in Blackboard.

### Sample Sound Files

Here are some example sound files you can use with this assignment.

Topic revision: r1 - 2018-04-08 - 18:40:22 - Main.troy

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