Topic 1f - CFU Answers

Consider the following questions that ask you to determine the size of the file storing different media.

  1. I am going camping and I send my spouse a text message saying "Made it to the campground safetly. It's beautiful!!!" Assuming that the message is encoded in Unicode format (16-bits), how many bytes of data are needed to store this message?

 

First, I need to know how many characters are in the message. I count 52 (including spaces and exclamation points).

If each character requires 16 bits of storage then the message requires

52*16 = 832 bits

or

52*16 / 8 = 104 bytes of memory [remember, 8 bits per byte]

 

  1. I took a 2400x1600 pixel photo of my campsite and sent it to my spouse. Assuming that the image was stored in 24 bit color, and uncompressed, approximately how many kilobytes of storage are needed to store this photo?

If the image is 2400x1600 then there are:

2400 * 1600 = 3,840,000 pixels in the image

Each pixel requires 24 bits of memory so this is

3,840,000 * 24 = 92,160,000 bits

or

92,160,000 / 8 = 11,520,000 bytes

or

11,520,000 / 1024 = 11,250 kilobytes [remember that there are 1,024 bytes of memory in a kilobyte]

 

  1. In the middle of the night I hear a strange noise outside of my tent. I record this sound using 16-bit mono with a samplng rate of 44100. If I send 15 seconds of this sound to my spouse, how many kilobytes of storage are needed to store this uncompressed sound file?

 

15 seconds of sound, times 44,100 samples per second, times 16 bits per sample means

15*44100*16 = 10,584,000 bits

or

10,584,000 / 8 = 1,323,000 bytes

or

1,323,000 / 1024 = approximately 1292 kilobytes

or

1,323,000 / 1024 / 1024 = approximately 1.26 megabytes