LSP-based multiple-description coding for real-time low bit-rate voice over IP

• Published in: IEEE transactions on multimedia Vol. 7; no. 1; pp. 167 - 178
• Main Authors: Wah, B.W., Dong Lin
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2005; Institute of Electrical and Electronic Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Applied sciences; Artificial intelligence; Bandwidth; Bit rate; Computer science; control theory; systems; Correlation; Delay; Descriptions; Exact sciences and technology; Excitation; Information, signal and communications theory; Interleaved codes; Internet; Internet telephony; IP networks; Line Spectral Pairs; loss concealment; low bit-rate speech coding; multiple-description coding; Playbacks; Propagation losses; Quality of service; Real time; Signal processing; single-description coding; Speech; Speech and sound recognition and synthesis. Linguistics; Speech processing; Studies; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Transmission; UDP; Voice; voice over IP; Wireless application protocol; UDP; Line Spectral Pairs; low bit-rate speech coding; Packet switching; Linear interpolation; Internet protocol; Voiced signal; single-description coding; Transmission time; Line spectrum; multiple-description coding; Speech coding; loss concealment; Internet; Low bit rate; Transmission loss; voice over IP
• ISSN: 1520-9210; 1941-0077
• DOI: 10.1109/TMM.2004.840593

A fundamental issue in real-time interactive voice transmissions over unreliable IF networks is the loss or late arrival of packets for playback. This problem is especially serious when transmitting low bit rate-coded speech with pervasive dependencies introduced. In this case, the loss or late arrival of a single packet will lead to the loss of subsequent dependent frames. We study end-to-end loss-concealment schemes for ensuring high quality in playback. We propose a novel multiple description-coding method for concealing packet losses in transmitting low bit rate-coded speech. Based on high correlations observed in linear predictor parameters-in the form of Line Spectral Pairs (LSPs)-of adjacent frames, we generate multiple descriptions in senders by interleaving LSPs, and reconstruct lost LSPs in receivers by linear interpolations. As excitation codewords have low correlations, we further enlarge the segment size for excitation generation and replicate excitation codewords in all the descriptions in order to maintain the same transmission bandwidth. Our proposed scheme can be extended easily to more than two descriptions and can adapt its number of descriptions dynamically to network-loss conditions. Experimental results on FS-1016 CELP, ITU G.723.1, and FS MELP coders show good performance of our scheme.