27 December 1999 Speech-property-based FEC for Internet telephony applications
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In this paper we first analyze the concealment performance of the G.729 decoder. We find that the loss of unvoiced frames can be concealed well. Also, the loss of voiced frames is concealed well once the decoder has obtained sufficient information on them. However the decoder fails to conceal the loss of voiced frames at an unvoiced/voiced transition because it extrapolates internal state (filter coefficients and excitation) for an unvoiced sound. Moreover, once the encoder has failed to build the appropriate linear prediction synthesis filter, it takes a long time for the decoder to resynchronize with the encoder. Using this result, we then develop a new FEC scheme to support frame-based codecs, which adjusts the amount of added redundancy adaptively to the properties of the speech signal. Objective quality measures (ITU P.861A and EMBSD) show that our speech property-based FEC scheme achieves almost the same speech quality as current FEC schemes while approximately halving the amount of necessary redundant data to adequately protect the voice flow.
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Henning A. Sanneck, Henning A. Sanneck, Nguyen Tuong Long Le, Nguyen Tuong Long Le, } "Speech-property-based FEC for Internet telephony applications", Proc. SPIE 3969, Multimedia Computing and Networking 2000, (27 December 1999); doi: 10.1117/12.373533; https://doi.org/10.1117/12.373533

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