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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MPEG-1 Layer I to III


The three layers were introduced, so that different requirements on the complexity of the compression can be taken into account. The first layer is the most simple and requires the smallest expenditure for encoding and decoding. Layer III provides the most extensive functionality and achieves the highest quality.


While the MP3 format is wide-spread, layer I and II are hardly used. This is primarily caused by obsolete assumptions about the efficiency of the hardware resources. Due to the fact that a higher layer offers a better quality at the same transfer rate, there is no reason to support the subordinated layers.


Originally layer II coding was used with the DCC (Digital Compact Cassette), which were intended as follow-up system for the analogue cassette (by Philips). The DCC achieved a quality level similar to CD, but could not be established at the market.


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MPEG-1 Audio MPEG-1 Audio Sampling and Bit Rate