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MPEG-4 Book, The by Touradj Ebrahimi, Fernando Pereira

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10.2. Overview of MPEG-4 Speech Coders

MPEG-4 speech coding tools [MPEG4-3] consist of two different basic algorithms: CELP [Nomu98] and HVXC [Nish97a]. They provide not only high coding efficiency but also a variety of new functionalities, such as bit-rate scalability (also known as embedded coding); bit-rate controllability, which allows modification of the bit rate during encoding; variable bit-rate coding; and speed and pitch changes. Users can choose the best algorithm for their applications and requirements.

The CELP algorithm operates from 3.85 to 23.8 kbit/s for speech signals of 8- and 16-kHz sampling rate with two different excitation modes—that is, multipulse excitation (MPE) and regular pulse excitation (RPE). Parametric speech coding, ...

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