COMP 3663 Media Formats

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COMP 3663Media Formats

• Originally Prepared by
• Daniel Maek, January, 2003

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Media Formats

• What are media?

A medium (plural media) is a carrier of
something in the most popular sense, of
information, mostly human ideas.
What is a file format?
A file format is a way to encode data for
storage in a computer file.
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Media Formats
Types of media formats

• Text
• Graphics
• Audio
• Video

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Text
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Text

• Plain Text

Extension .txt

• Details
• Only text data
• Universally supported
• No formatting
• Human readable

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Text

• Rich Text Format

Extension .rtf

• Details
• Developed by Microsoft
• Supported across different platforms
• Allows formatting
• Editable documents

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Text

• HTML

Extensions .htm or .html

• Details
• Developed by W3C
• Formatting and style
• Structural layout
• Hypertext Links
• Used on WWW

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Graphics
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Graphics

• Vector Graphics

Bitmap Graphics

• Rectangular array of pixels
• Loose detail when scaled
• Useful for photos and paintings
• Quite large

• Mathematical primitives
• Scales without loss of detail
• Useful for diagrams and illustrations
• Requires little space

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Graphics

• Colour depth

• Amount of information stored for each pixel
• More colours means more space required
• Transparency

True Colour
256 Colours
16 Colours
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Graphics

• Compression

• Reduces size of data
• Lossy vs. lossless

Size

• Same image
• Different formats

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Graphics

• Windows Bitmap

Extension .bmp

• Details
• Used by Microsoft
• Lack of compression

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Graphics
GIF
Extension .gif

• Details
• Graphics Interchange Format
• Used on the WWW
• Nonlossy LZW compression
• Only 256 colours
• Interlaced
• Animation

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Graphics

• PNG

Extension .png

• Details
• Portable Network Graphics
• Meant to replace GIF
• Good compression
• High color, transparency
• Interlaced
• No animation
• Open

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Graphics
JPEG
99 Quality
Extension .jpg .jpeg

• Details
• Joint Photographic Experts Group
• Lossy compression
• High colour
• Useful for photos

50 Quality
1 Quality
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Graphics

• PostScript and EPS

Extension .ps and .eps

• Details
• Developed by Adobe
• Page description language
• Vector based
• Laser printers
• EPS for small images

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Graphics
PDF
Extension .pdf

• Details
• Portable Document Format
• Developed by Adobe
• Documents always look the same
• Compressed
• Not editable

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Graphics

• Macromedia Flash

Extension .swf

• Details
• Vector based
• Animation
• Interactive
• ActionScript

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Graphics
SVG
Extension .svg

• Details
• Scalable Vector Graphics
• Meant for WWW
• Based on XML
• Animation
• Competes with Flash
• Open standard

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Audio
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Audio

• Waveforms

Synthesized music

• Stored as a sampled wave
• Played back immediately
• WAV, MP3
• Large
• Can represent any sound

• Stored as notes, commands
• Played using samples
• MIDI
• Small files

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Audio

• File Format

• Storing the data
• Data can be encoded using different codecs

Codec

• Coder/decoder
• Transforms the data between encoded and raw
• Encoded good for storage and transport
• Raw good for viewing/playback

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Audio

• Compression

• Uncompressed sound data can be very large
• 16bit, 44.1kHz, stereo 1 sec 186kB
• Lossy vs. lossless

Streaming

• Allow listening on the fly
• Online radios

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Audio
WAV
Extension .wav or .aiff

• Details
• Lossless file format
• Variety of codecs
• Good quality
• Large size

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Audio
AU
Extension .au

• Details
• Designed by Sun
• Mostly UNIX
• Several data formats

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Audio
MP3
Extension .mp3

• Details
• Lossy compression
• Quality vs. size
• Streaming

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Audio
Ogg Vorbis
Extension .ogg

• Details
• Open source
• Lossy compression
• Competition to MP3
• Widely spread
• VBR
• Streaming

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Audio
Real Audio
Extension .ra

• Details
• Lossy compression
• Streaming
• Low quality
• Proprietary
• Real will move to support Ogg Vorbis

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Audio
Windows Media Audio
Extension .wma

• Details
• Designed by Microsoft
• Proprietary format
• Supports copy control

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Audio
MIDI
Extension .mid

• Details
• Synthesized music
• Very small files
• Limited set of instruments

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Video
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Video

• Compression

• Essential due to large volumes of data
• A DVD contains over 4GB of compressed video
• Lossy

Streaming

• Live broadcasts
• Videoconferencing

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Video
AVI
Extension .avi

• Details
• Audio Video Interleave
• Designed by Microsoft
• Simultaneous playback
• Wrapper for many codecs

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Video
Real Video
Extension .rm or .ram

• Details
• Companion to Real Audio
• Streaming
• Low quality
• Small size
• Proprietary

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Video
QuickTime
Extension .qt

• Details
• Designed by Apple
• Wrapper for audio, video, text and effects
• Mainly Mac

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Video
DivX
Extension usually .avi

• Details
• Created by DivXNetworks, Inc.
• High compression ratios
• Popular

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Resources

• Wikipedia
• http//www.wikipedia.org
• Wikipedia, the free encyclopedia

Wotsits File Formats http//www.wotsit.org The
definitive source of file format information
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Questions