1.3 File Compression

Question 1

What is lossless file compression?

Answer 1

Original data can be reconstructed upon decompression, important where loss of data is disastrous - spreadsheets, research)

Question 2

What is lossy file compression?

Answer 2

File compression algorithm eliminates unnecessary data (JPEG). Minimal loss in detail.

Question 3

What is MPEG-3?

Answer 3

Uses technology known as audio compression to convert music into MP3. Reduce original file size by 90%

Question 4

What is perceptual music shaping?

Answer 4

Removes certain sounds in algorithms like MP3. Removes frequencies outside of human range. If two sounds are played at the same time, softer one is removed.

Question 5

What is Run Length Encoding? (RLE)

Answer 5

Used to compress a number of different file formats.
Lossless compression, reduces size of a string of adjacent, identical dara.
First two values represent number of identical data items, second value represents code of data item.

Question 6

How to reduce size of movie files?

Answer 6

• reduce sampling rate
• reduce sampling resolution
• reduce frame rate

Question 7

How to reduce size of image files?

Answer 7

• crop image
• decrease colour depth
• reduce image resolution