Parameter interpolation to enhance the frame erasure robustness of CELP coders in packet networks
نویسندگان
چکیده
Frame erasure (FE) robustness is an important quality measure for voice over IP networks (VoIP). Recovery of the erased frames from the received information is crucial to realize this robustness. We allow the lost frames to be recovered from both the “previous” and “next” good frames. We first give quantitative distortion comparisons between predictive and interpolative frame recovery. Then we add FE-robust LSF coding modes to the popular ITU G.723.1 and G.729 CELP coders. These FE-robust modes utilize intraframe LSF VQ and invoke no bit-rate increase for the G.723.1 coder and a small increase (0.4 kb/s) for G.729. Simulations show that FE robust coding with interpolation achieves average spectral distortions 0.7-1.8 dB smaller than that of the original coders. Significant quality improvement was achieved by combined implementation of FE robust coding, LSF and pitch interpolation, and a proposed fixed codebook excitation recovery method.
منابع مشابه
LSF Quantization to Enhance the Frame Erasure Robustness of CELP Type Coders in Packet Networks
quantizers were designed with the primary concerns of bit-rate and complexity, less attention was paid to error propagation. In this paper, we consider the erasure performance of LSF differential scalar quantizer (DSQ) and compare it with the interframe coding method embedded in the standard G723.1 of the ITU. Our results show that with only 5% extra bit-rate, DSQ algorithm is much more robust ...
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