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]
Featuresedit
The main advantage of ACELP is that the algebraic codebook it uses can be made very large (> 50 bits) without running into storage (RAM/ROM) or complexity (CPU time) problems.
Technologyedit
The ACELP algorithm is based on that used in code-excited linear prediction (CELP), but ACELP codebooks have a specific algebraic structure imposed upon them.
A 16-bit algebraic codebook shall be used in the innovative codebook search, the aim of which is to find the best innovation and gain parameters. The innovation vector contains, at most, four non-zero pulses.
In ACELP, a block of N speech samples is synthesized by filtering an appropriate innovation sequence from a codebook, scaled by a gain factor gc, through two time-varying filters.
The long-term (pitch) synthesis filter is given by:
^. 14 October 2007. Archived from the original on 14 October 2007.
^VoiceAge Corporation (13 October 2007). . Archived from the original on 13 October 2007. Retrieved 20 September 2009.
^VoiceAge Corporation. . VoiceAge Corporation. Archived from the original on 18 October 2009. Retrieved 20 September 2009.
^VoiceAge Corporation. . Archived from the original on 14 October 2007. Retrieved 3 January 2010.
^US patent 5717825, "Algebraic code-excited linear prediction speech coding method", issued 10 February 1998
January 01, 1970
algebraic, code, excited, linear, prediction, acelp, speech, coding, algorithm, which, limited, pulses, distributed, excitation, linear, prediction, filter, linear, predictive, coding, algorithm, that, based, code, excited, linear, prediction, celp, method, al. 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 Universite 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 Features editThe main advantage of ACELP is that the algebraic codebook it uses can be made very large gt 50 bits without running into storage RAM ROM or complexity CPU time problems Technology editThe ACELP algorithm is based on that used in code excited linear prediction CELP but ACELP codebooks have a specific algebraic structure imposed upon them A 16 bit algebraic codebook shall be used in the innovative codebook search the aim of which is to find the best innovation and gain parameters The innovation vector contains at most four non zero pulses In ACELP a block of N speech samples is synthesized by filtering an appropriate innovation sequence from a codebook scaled by a gain factor g c through two time varying filters The long term pitch synthesis filter is given by 1 B z 1 1 g p z T displaystyle frac 1 B z frac 1 1 g p z T nbsp The short term synthesis filter is given by 1 A z 1 1 i 1 P a i z i displaystyle frac 1 A z frac 1 1 sum i 1 P a i z i nbsp References edit Transfer of technology ACELP map VoiceAge Corporation Archive org Related Standards Specifications 14 October 2007 Archived from the original on 14 October 2007 VoiceAge Corporation 13 October 2007 Codec Technologies Archived from the original on 13 October 2007 Retrieved 20 September 2009 VoiceAge Corporation Codec Technologies VoiceAge Corporation Archived from the original on 18 October 2009 Retrieved 20 September 2009 VoiceAge Corporation ACELP net Beyond the Standards Archived from the original on 14 October 2007 Retrieved 3 January 2010 US patent 5717825 Algebraic code excited linear prediction speech coding method issued 10 February 1998 Retrieved from https en wikipedia org w index php title Algebraic code excited linear prediction amp oldid 1160789678, wikipedia, wiki, book, books, library,
