Abstract
Abstract In a bid to enhance the search performance, this paper presents an improved version of reduced candidate mechanism (RCM), an algebraic codebook search conducted on an algebraic code-excited linear prediction (ACELP) speech coder. This improvement is made based on two findings in a piece of our prior work. The first finding is that a pulse with a high contribution in the associated track is more likely to serve as an optimal pulse in the optimal codevector and the second is that the speech quality can be well maintained at a search accuracy above 50% approximately. Subsequently, a new finding in this study concerning a structured algebraic codebook in G.729 indicates that there is a 0.8321 probability that the number 1 ranked pulse in a global sorting by pulse contribution is indeed one of the optimal pulses. Hence, the number 1 pulse in the global sorting is labeled as one of the optimal pulses, following which a sequence of search tasks are fulfilled through RCM. This proposed complexity reduction algorithm, implemented on a G.729A speech codec, takes as few as eight searches, a search load tantamount to 2.5% of G.729A, 12.5% of global pulse replacement method (iteration = 2), 16.7% of iteration-free pulse replacement method, and 50% of RCM (N = 2). This proposal is thus found to successfully reduce the required computational complexity to a great extent as intended.
Highlights
1 Introduction An algebraic code-excited linear prediction (ACELP)based speech coding technique [1-3] is a type of technique most widely applied to digital speech communication systems and serves as a mainstream technique adopted in a great number of speech coding standards due to a double advantage of low bit rates and high speech quality
The price paid is a high computational complexity requirement, in an algebraic codebook search, due to the reason that it necessitates a tremendous computational load when conducting a full search over the algebraic codebook to locate the optimal pulses
5 Conclusions An improved version of reduced candidate mechanism (RCM) approach is presented in this work as an efficient means to enhance the performance of search over an algebraic codebook when applied to a G.729A speech codec
Summary
An algebraic code-excited linear prediction (ACELP)based speech coding technique [1-3] is a type of technique most widely applied to digital speech communication systems and serves as a mainstream technique adopted in a great number of speech coding standards due to a double advantage of low bit rates and high speech quality. In the IFPR method, new pulses are sought by a number of pulse replacements at a time following pulse contributions evaluated for every track so as to maximize over all combinations a search criterion, which replaces the pulses pertaining to the initial codevector with the most significant pulses for every track.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: EURASIP Journal on Audio, Speech, and Music Processing
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
