Code-excited linear prediction

About: Code-excited linear prediction is a research topic. Over the lifetime, 2025 publications have been published within this topic receiving 28633 citations. The topic is also known as: CELP.

A Comparison of entropy coding performances between scalar and vector quantized speech LPC parameters

Abstract: The performances of entropy coding for scalar and vector quantized speech LPC parameters (LSPs) are investigated. It is shown that condition.ally optimized scalar quantization (SQ) has advantagies over vector quantization (VQ) when entropy coding is considered af ter quantization. At a similar distortion rate, the SQ-based system is more robust and has simpler implementation. VQ-based systems have difficulty in encoding LSP at low-distortion (high quality speech) because of the difficulty of using large codebook size.

Method and apparatus for searching excitation codebook in code excited linear prediction (CELP) coder

Abstract: A method for selecting a code vector in an algebraic codebook wherein the analysis window for the coder is extended beyond the length of the target speech frame. By extending the analysis window, the two dimensional impulse response matrix can be stored as a one dimensional autocorrelation matrix greatly saving on the computational complexity and memory required for the search.

Code excited sample-by-sample gain adaptive coding for lossless compression of audio signals

Abstract: A coding algorithm for lossless compression of audio signals is presented. The proposed algorithm consists of a lossy coding part and a lossless coding part. The lossy coding part is based on code excitation approach where the excitation gain and the short-term prediction coefficients are adapted in a sample-by-sample fashion to cope with rapid time-varying nature of audio signals. The error between the input and the code-excited synthetic signal is then encoded by an arithmetic coder to achieve lossless compression. The excitation codebook is searched by using an M-L tree search strategy with minimum error energy and minimum code length after arithmetic coding as search criteria. The proposed coder has very low decoding complexity due to its simple code excitation structure and achieves compression performance comparable to other advanced lossless coders for coding CD quality audio.

Speech coding/encoding using celp

Abstract: A speech coding system of the code excited linear prediction (CELP) type comprises means (24,26) for filtering digitised speech samples to form perceptually weighted speech samples. Entries in a one-dimensional codebook (110) comprising frame length sequences are filtered in a perceptually weighted synthesis filter (28) to form a one-dimensional filtered codebook (38). The filtered codebook entries are compared with the perceptually weighted speech signals to obtain a codebook index which gives the minimum perceptually weighted error when the speech is resynthesised. Using a one-dimensional codebook (110) reduces the amount of computation which is required compared to using a two-dimensional codebook.