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


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The central mechanism of MPEG 1 audio is the subdivision of the original data into frequency domains. Information about the frequency distribution is then available.


Thus it can be distinguished, in which measure the individual frequencies are involved in the complete audio signal. Those frequency domains will be denoted as subbands. The MPEG 1 standard defines 32 subbands in total.


The two layer I and II provide a simpler model, than the more complex Layer III. Additionally layer III offers an enhanced option, the so-called MDCT (modified discrete cosine transform). The MDCT produces clearly better results with certain contents.


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MPEG-1 Audio Principle of the coding Acoustic Model