Code-Excited Linear Prediction

Code ( -book) Excited Linear Prediction ( CELP ) is a hybrid method for audio data compression, which combines the advantages of the waveform coding using vector quantization and parametric methods. The result is a good voice quality, the / s corresponds, even at low data rates 4-16 kbit approximately from pulse-code modulation. The process is described in Part 3 of the MPEG -4 standard (ISO / IEC 14496-3 ).

The basis for most Hybridcodierverfahren coding using linear prediction ( linear predictive coding, LPC ), the remaining residual signal is compressed by " looking up " ( quantization) in a table - usually 40 samples (5- ms ) signal by 10 bit ( table with 1024 entries) ready. By table lookup the compression -consuming and resource-intensive than decompression.

The biggest disadvantage of CELP, a signal delay of about 50 ms, was in the 1992 standardized G.728 "low -delay CELP codec" reduced to less than 2 ms. A patented development of the process represents the Algebraic Code Excited Linear Prediction ( ACELP )