Robust Ultra-Low Latency Soft-Decision Decoding of Linear PCM Audio

• Published in: IEEE transactions on audio, speech, and language processing speech, and language processing, 2013-11, Vol.21 (11), p.2324-2336
• Main Authors: Pflug, Florian, Fingscheidt, Tim
• Format: Article
• Language: English
• Subjects: Algorithms; Applied sciences; Audio decoding; Audio signals; Bayes methods; Bayesian methods; Channels; Codes; Coding, codes; Decoding; Delay; Digital; error concealment; Exact sciences and technology; Fading; Information, signal and communications theory; Markov processes; Microphones; Miscellaneous; Modulation, demodulation; normalized least-mean-square (NLMS) algorithm; prediction methods; Redundancy; Robustness; Signal and communications theory; Signal processing; Speech; Telecommunications and information theory
• ISSN: 1558-7916; 2329-9290; 1558-7924; 2329-9304
• DOI: 10.1109/TASL.2013.2273716

Applications such as professional wireless digital microphones require a transmission of practically uncoded high-quality audio with ultra-low latency on the one hand and robustness to error-prone channels on the other hand. The delay restrictions, however, prohibit the utilization of efficient block or convolutional channel codes for error protection. The contribution of this work is fourfold: We revise and summarize concisely a Bayesian framework for soft-decision audio decoding and present three novel approaches to (almost) latency-free robust decoding of uncompressed audio. Bit reliability information from the transmission channel is exploited, as well as short-term and long-term residual redundancy within the audio signal, and optionally some explicit redundancy in terms of a sample-individual block code. In all cases we utilize variants of higher-order linear prediction to compute prediction probabilities in three novel ways: Firstly by employing a serial cascade of multiple predictors, secondly by exploiting explicit redundancy in form of parity bits, and thirdly by utilizing an interpolative forward/backward prediction algorithm. The first two presented approaches work fully delayless, while the third one introduces an ultra-low algorithmic delay of just a few samples. The effectiveness of the proposed algorithms is proven in simulations with BPSK and typical digital microphone FSK modulation schemes on AWGN and bursty fading channels.