Data Compression


Criteria

Survey Formats

Basics

Compression Methods

Data Formats

Files

Audio Data

MPEG-1 Audio

MPEG-1 Layer I to III

Sampling and Bit Rate

Variable Bit Rates

Principle of the coding

Filter

Acoustic Model

Entropy Coding

Encoding (Diagram)

Image Data

Video Data


Glossary

Index


Download


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Variable Bit Rates


The bit rates specified for layer I and II are constant and must not vary for the entire data stream. Applications supporting layer III has to process variable bit rates.


A variable rate gives the opportunity to the encoder to react on phases with complex audio contents. Prerequisite for this option is, that phases immediately following require a lower transfer rate. Otherwise the average data transfer rate cannot be kept, what causes synchronization problems e.g. for streaming applications.


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MPEG-1 Audio Sampling and Bit Rate Principle of the coding