Variable bit rate MBELP speech coding via V/UV distribution dependent spectral quantization
نویسندگان
چکیده
A variable bit rate multiband excited linear predictive speech coder is proposed in this paper. Speech signal is compressed in different bit rates ranging from 0.88 kbps to 2.6 kbps according to the mode of operation and the optimum V/UV transition frequency. An average bit rate of 1.24 kbps is achieved. The proposed speech coder improves the speech quality by splitting the non-stationary speech segments for analysis. The V/UV distribution of a short-time speech spectrum is represented efficiently by using a closed-loop minimised V/UV transition frequency. Depending on the V/UV transition frequency, the spectrum envelope is quantized in variable bit rate through embedded differential predictive scalar and vector quantizations of the LSP parameters. The proposed spectral quantization scheme results in a spectral distortion comparable to a fixed 24bit 2-dimensional differential scalar quantization scheme.
منابع مشابه
Ultra low bit-rate speech coding based on unit-selection with joint spectral-residual quantization: no transmission of any residual information
A recent trend in ultra low bit-rate speech coding is based on segment quantization by unit-selection principle using large continuous codebooks as a unit database. We show that use of such large unit databases allows speech to be reconstructed at the decoder by using the best unit’s residual itself (in the unit database), thereby obviating the need to transmit any side information about the re...
متن کاملVariable Dimension Vector Quantization of Speech Spectra for Low Rate Vocoders
Optimal vector quantization of variable-dimension vectors in principle is feasible by using a set of fixed dimension VQ codebooks. However, for typical applications, such a multi-codebook approach demands a grossly excessive and impractical storage and computational complexity. Efficient quantization of such variable-dimension spectral shape vectors is the most challenging and difficult encodin...
متن کاملEntropy Coding of Spectral Envelopes for Speech and Audio Coding Using Distribution Quantization
Speech and audio codecs model the overall shape of the signal spectrum using envelope models. In speech coding the predominant approach is linear predictive coding, which offers high coding efficiency at the cost of computational complexity and a rigid systems design. Audio codecs are usually based on scale factor bands, whose calculation and coding is simple, but whose coding efficiency is low...
متن کاملVariable Rate Vector Quantization of the Speech Spectral Envelope
EEective rate variation during active speech is a necessary component of sophisticated variable rate speech compression schemes. Here, we use open-loop estimates of spectral shape to roughly determine signal bandwidth and bit allocations for variable rate encoding of spectral parameters. We analyze the application of the relative entropy functional to sets of Line-Spectrum Pairs (LSPs) and tran...
متن کاملLow bit-rate speech coding using quantization of variable length segments
This paper describes a new segmentation and quantization technique for low bit-rate speech coders. Bit-rate reduction is achieved by combining segmentation and quantization, where a segment consists of one or more adjacent frames. The algorithm for selecting and quantizing segments from a pre-determined number of frames extends the frame-based trellis techniques. It models the input speech as a...
متن کامل