Distributed video coding for wireless video sensor networks: a review of the state-of-the-art architectures <s> Enhancements to PRISM <s> In this work, we present PRISM (power-efficient, robust, high-compression, syndrome-based multimedia coding), a video coding paradigm based on the principles of coding with side information (which, unlike the classical Wyner-Ziv coding scenario Wyner, A et al. (1976), is characterized by an ambiguous state of nature characterizing the side-information Ishwar, P et al. (2003)). PRISM's architectural goals are to inherit the low encoding complexity and robustness of motion-JPEG style intra-frame video codecs while approaching the high compression efficiency of full-motion interframe video codecs. The PRISM paradigm roughly swaps the encoder-decoder complexity with respect to conventional video coding architectures through the novel concept of moving the motion compensation task from the encoder to the decoder. These traits make PRISM well-matched to uplink-rich media applications involving wireless video and security cameras, multimedia-equipped phones and PDA's etc. <s> BIB001 </s> Distributed video coding for wireless video sensor networks: a review of the state-of-the-art architectures <s> Enhancements to PRISM <s> We describe PRISM (power-efficient, robust, high-compression, syndrome-based multimedia coding), an error-resilient video-coding paradigm built on the principles of distributed source coding from multi-user information theory. PRISM represents a radical departure from the current state-of-the-art video coding architectures, like MPEG, that are based on a motion-compensated prediction framework. These are hampered by: (i) a rigid computational complexity partition between encoder (heavy) and decoder (light); and (U) high fragility to drift between encoder and decoder in the face of prediction mismatch due to channel loss. In contrast, PRISM's architectural goals are: (i) to have a channel-adaptive distribution of computational complexity between encoder and decoder; and (ii) to have built-in robustness to drift between encoder and decoder due to wireless channel loss. These features make PRISM ideally suited for low-latency multimedia transmission over wireless networks, particularly for uplink-rich applications. <s> BIB002
In BIB002 , multi-level coset codes for PRISM architecture are presented. The codebook for each level is computed by coding bit at that level B i and BIB001 the remaining (i − 1) bits are determined by the bits at previous levels B j (where B, i and j represents the coding bit, current coset level, and previous coset level, respectively, for 1 ≤ j ≤ i − 1). Therefore, quantization of X to the closest coset is done at the root level, which determines the path to the codebook of next level using partition tree that originally possesses the codeword for X. The encoded source bits are also determined by the codebook path and transmitted to the decoder. The total number of coset levels (and in turn the data rate) may vary depending on the distortion and noise that exist between the predictor and the received bitstream. Moreover, each coset level can be taken as a single level partition tree. In order to achieve the required rate for that level, a separate dedicated encoder and decoder can be designed. Although this slightly increases the complexity of the encoder, such a design allows the use of linear correction codes for each level and improves overall error resilience of the codec against channel and propagation errors.