Unit 202 - Lesson 5 - Compression

Digital MediaLesson 5

Lesson Goals Understand the term compression

Know different compression techniques

Be able to describe compression of media files

Compression RecapAudio, images and video files can all be compressed...

Understand compression featuresKnow lossy/lossless techniques

#lossless #lossy#compression

Audio Compression Audio files are generally compressed to allow devices to store a

large number of files on them at the same time:

WAV 30.4mb

WMA 15.6mb

MP3 4.2MB

MP31.4mb

192kbps

64kbps



Image Compression Image files are usually compressed for broadcast on the Internet,

sent via email or uploaded to a website at a smaller file size:



JPEG GIF

Video Compression Videos are compressed to ease uploading to a website where

they can be streamed or to be small enough to fit on DVD:



OGG MP4

Uncompressed Files An uncompressed digital media file

is one that is at the best quality it can ever be as it is an original file.

These files are generally unedited and typically have a very big file size as the hold all of the original data.

Uncompressed files are mainly used for storing media at it’s best quality before files are edited, compressed and broadcast elsewhere.

Examples: WAV, TIFF, AVI



Compressed Files An uncompressed digital media file

is one that has been made smaller using a compression technique.

These files are much smaller than uncompressed files and typically poorer quality too.

Compressed files are ones that may be used to store media on a portable devices or to upload media to a website.

Examples: MP3, JPG, WMV



Lossless Compression Lossless compression is the type

of compression where a formula is used calculating how to display the file.

No data is lost in this type of compression, it can be recovered again by uncompressing the file using the formula.

Lossless compression normally produces better quality files but they will be bigger file sizes than those using lossy compression.



Lossy Compression Lossy compression is the type of

compression that results in you losing some level of quality in the media file.

This type of compression gets rid of any data deemed unnecessary by combining similar colours.

This data is permanently lost, the file will never be as good as the original again.

Files that are compressed using this technique are much smaller in file size.





1.1kb60.1kb

Lossless Lossy



Your Task – Compression Define the following terms and

explain the difference between both relating to media files: Uncompressed Compressed

Explain the difference between lossy and lossless compression techniques on media files: Lossless Lossy

Provide some examples to help illustrate your research.



Keywords

Uncompressed

Compressed

Lossy/Lossless

The original file which is at maximum quality

A file made smaller for broadcasting on different platforms

Two different compression techniques


Education

Unit 202 - Lesson 5 - Compression