Tree searched multi-stage vector quantization of LPC parameters for 4 kb/s speech coding

Bhattacharya, Bhaskar; LeBlanc, W.P.; Mahmoud, S.A.; Cuperman, V.

doi:10.1109/icassp.1992.225961

Cited by 24 publications

(1 citation statement)

References 7 publications

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“…As can be seen, the complexity of the predictive quantizer is about one-third of the complexity of the pure split VQ quantizer. It is also estimated that the predictive VQ is a factor of 10 simpler than a multiple-stage quantizer, as proposed in [20], of similar performance.…”

Section: Complexity Issuesmentioning

confidence: 99%

An LSF quantizer for the North-American half-rate speech coder

Marca

1994

IEEE Trans. Veh. Technol.

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The design of the half-rate coder for the North-American cellular communication standard poses a challenging problem. The desired speech quality is that of the full-rate coder, but the total bit rate specified for the half-rate is only 6.5 kb/s. Since the mobile communication channel is very noisy, the use of error-correcting codes is necessary, which leaves only about 4 kb/s for the actual speech information. This very restricted bit budget requires that fewer than 30 b be allotted to the quantization of the LSF parameters, which precludes the use of scalar quantization. In this work, a quantizer design procedure which is tailored for the transmission frame structure of the North-American (TIA) cellular communication standard is presented. It is basically a split vector quantizer which makes use of interframe prediction to lower the number of bits required for quantization. Since the prediction is performed only on every other frame, the error propagation is limited. The quantization technique yields good performance in the 26-27 blfiame range, and the complexity of its implementation is less than 0.5 Mip.

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Section: Complexity Issuesmentioning

confidence: 99%

An LSF quantizer for the North-American half-rate speech coder

Marca

1994

IEEE Trans. Veh. Technol.

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Performance of LSF vector quantizers for VSELP coders in noisy channels

Dall'agnol

Alcaim

Marca

1994

Trans Emerging Tel Tech

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Efficient quantization of synthesis filter coefficients for CELP (Code Excited Linear Prediction) coders is essential to achieve high quality speech at low rates. Three vector quantizers with good potential for utilization in low rate coders are studied. Each of them is implemented inside the structure of the VSELP (Vector Sum Excited Linear Prediction) coder, an important member in the class of CELP coders. These three vector quantizers are used to encode LSF (Line Spectral Frequency) parameters and are compared in terms of robustness to channel errors, complexity and quality of synthesized speech. Performance of synthesized speech is evaluated considering the objective measure of frequency weighted signal to noise ratio and subjective results obtained from listening tests. With the purpose of improving the robustness to channel errors, the application of simulated annealing to assign binary indices to the output levels of the quantizer is also investigated. A split vector quantization scheme which employs interframe prediction has shown to be an attractive approach to encode the synthesis filter parameters. It provides a performance comparable to the IS‐54 scheme and uses 10 bits less for each LSF frame.

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On encoding pitch and LPC parameters for low‐rate speech coders

Copperi

1994

Trans Emerging Tel Tech

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This paper describes the development of efficient methods to encode the parameters of long‐term (pitch) and short‐term (LPC all‐pole) prediction filters with a limited bit‐rate, such that the design of high quality speech coders in the 3–4 kbit/s range becomes easier. Our results indicate that good performance can be reached with about 800 bit/s to represent both the pitch lags and the coefficients of a three‐tap pitch filter, thus achieving a significant 36% bit‐rate reduction in comparison with conventional quantization techniques, and using 24 bit/frame to encode spectral parameters relative to a multilanguage speech database.

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Tree searched multi-stage vector quantization of LPC parameters for 4 kb/s speech coding

Cited by 24 publications

References 7 publications

An LSF quantizer for the North-American half-rate speech coder

An LSF quantizer for the North-American half-rate speech coder

Performance of LSF vector quantizers for VSELP coders in noisy channels

On encoding pitch and LPC parameters for low‐rate speech coders

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