Algebraic code-excited linear prediction

Algebraic code-excited linear prediction (ACELP) is a speech coding algorithm in which a limited set of pulses is distributed as excitation to a linear prediction filter. It is a linear predictive coding (LPC) algorithm that is based on the code-excited linear prediction (CELP) method and has an algebraic structure. ACELP was developed in 1989 by the researchers at the Université de Sherbrooke in Canada.[1]

The ACELP method is widely employed in current speech coding standards such as AMR, EFR, AMR-WB (G.722.2), VMR-WB, EVRC, EVRC-B, SMV, TETRA, PCS 1900, MPEG-4 CELP and ITU-T G-series standards G.729, G.729.1 (first coding stage) and G.723.1.[2][3][4][5] The ACELP algorithm is also used in the proprietary ACELP.net codec.[6] Audible Inc. use a modified version for their speaking books. It is also used in conference-calling software, speech compression tools and has become one of the 3GPP formats.

The ACELP patent expired in 2018 and is now royalty-free.[7]

  1. ^ "Transfer of technology".
  2. ^ ACELP map, VoiceAge Corporation, Archive.org
  3. ^ "Related Standards Specifications". 14 October 2007. Archived from the original on 14 October 2007.
  4. ^ VoiceAge Corporation (13 October 2007). "Codec Technologies". Archived from the original on 13 October 2007. Retrieved 20 September 2009.
  5. ^ VoiceAge Corporation. "Codec Technologies". VoiceAge Corporation. Archived from the original on 18 October 2009. Retrieved 20 September 2009.
  6. ^ VoiceAge Corporation. "ACELP.net — Beyond the Standards". Archived from the original on 14 October 2007. Retrieved 3 January 2010.
  7. ^ US patent 5717825, "Algebraic code-excited linear prediction speech coding method", issued 10 February 1998