MGMT 1030 Lecture Notes - Lecture 20: Bit Rate, Lossless Compression, Data Degradation
6 May 2018
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MGMT 1030 Tutorial 20 Notes – Data compression
Introduction
• The header contains 2 bytes of synchronization and MP3 version data followed by the
bit rate, the audio sample rate, the type of data (for example, stereo or monaural
audio), copy protection, and other information.
• The MP3 standard requires that each frame contains 384, 576, or 1152 audio samples of
data.
• Note that this format allows the bit rate to vary for each frame, allowing for more
efficient compression, but more difficult encoding procedures.
• The volume of multimedia data, particularly video
• Also sound and even high resolution still images, often makes it impossible or
impractical to store, transmit, and manipulate the data in its normal form. Instead it is
desirable
• In some cases, necessary to compress the data.
• This is particularly true for video clips, real-time streaming video with sound, lengthy
sound clips, and images that are to be transmitted across the Internet through modem
connections.
• It is also true of large data and program files of any type.
• There are many different data compression algorithms
• All fall into one of two categories, lossless or lossy.
• A lossless algorithm compresses the data in such a way that the application of a
matching inverse algorithm restores the compressed data exactly to its original form.
• Lossy data compression algorithms operate on the assumption that the user can accept
a certain amount of data degradation as a trade-off for the savings in a critical resource
such as storage requirements or data transmission time.
• Of course, only lossless data compression is acceptable for files where the original data
must be retained, including text files, program files and numerical data files.
• Lossy data compression is frequently acceptable in multimedia applications.
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