Media Types Flashcards
What is compression?
Compression means to reduce the size of a data file e.g. a document, video, image, sound file etc.
Why should you compress large files?
Because they take up a lot of storage on your hard disk. They will also take longer to send as an attachment by email. Compressed files can also be downloaded from the internet quickly.
What is lossy compression?
Lossy compression techniques compress data with a certain amount of visual loss when restored. However, audio and video can tolerate loss and it may not be noticeable to the human ear or eye.
Why is lossy compression not used for business data?
Business and legal documents require 100% restoration
What is lossless compression?
It is a technique that decompresses data back to its original form without any loss. All compression methods used to compress text, databases and other business data are lossless.
What is FLAC?
Free Lossless Audio Codec is a common audio format.
How are MP3 audio files compressed?
They use a technique using perceptual noise shaping. Certain parts of a song can be eliminated without significantly hurting the quality of the song for the listener.
How is video generally compressed?
A video is compressed frame by frame removing some data that will not affect the picture too much.
How does the MPEG format work?
It will look at an individual frame and compare it to the next frame. The difference between frames will be kept and the rest of the content in the frame that has not changed will not be save again.
What is the most common example of a lossy compression format?
JPEG
How are graphic formats such as JPEG compressed?
By grouping colours of a similar shade into the same colour.
Give two examples of lossless compression techniques.
RLE and LZW.
What are three examples of lossy compression?
MP3, JPEG and MP4
What are three examples of lossless compression?
WAV, PNG and text
