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The Concept
The Algorithm

    - Layer Coding Options
    - Hybrid Filter Bank
    - Psychoacoustics Model
    - Bit Allocation
The Hybrid Filter Bank

The purpose of the filter bank is to divide the audio signal into 32 equal-width frequency subbands. Empirical evidence has shown that the human ear has a limited resolution that can be expressed in terms of critical bandwidths less than 100Hz and more than 4kHz. Within a critical bandwidth the human ear blurs frequencies. Thus the filter bank creates equal-width frequency subbands that correlate to the critical bandwidths in a method diagrammed in the following figure.

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While Layer 1 and Layer 2 uses just a polyphase filterbank, an additional MDCT is used in Layer 3 compression.

Next step: Psychoacoustics Model

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