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Multiple description coding (MDC) can be applied for multipath communication to reduce the negative affect of packet loss, and it is composed of three processes: encoding, quantizing, and decoding. Encoding and decoding are well researched in MDC, but there are few researches that focus on the quantization process. Therefore, this paper focuses on the quantization process of MDC. The aim of this paper...
All transformed coefficients in a TU (Transform Unit) are equally quantized in the HEVC (High Efficiency Video Coding) standard. Such an equal quantization is not efficient because the transformed coefficients in the TU are not equally distributed. Moreover, the quantized coefficients scanning order method in the HEVC standard takes into account the distribution of the quantized coefficients in the...
The combination of log-likelihood ratio (LLR) quantization and network coding was previously shown to be a promising compress-and-forward strategy for the multiple access relay channel with two sources. In this paper, we generalize this approach to the case of more than two sources. Our proposed relay scheme consists of a scalar LLR quantizer for each source followed by a network coding (NC) step...
Low-density parity-check (LDPC) codes constructed over the Galois field GF(q) (q>2), which are also called non-binary LDPC codes, are an extension of binary LDPC codes with significantly better performance. In this paper, an efficient column-layered decoding algorithm, which can reduce the message memory as well as the average number of iterations dramatically, is proposed for min-max decoding...
Nowadays, multimedia data protection widely uses data hiding technology like Digital Watermarking or steganography. Among the large offer of watermarking techniques several ones are now based on the side information scheme proposed by Costa. These techniques mainly use scalar quantization for embedding a given information. Such solutions have good properties in terms of robustness and capacity but...
This paper is concerned with transform coding of correlated sources in conjunction with variable rate quantization at high resolution. The approach builds on our prior work on optimality conditions for transform coding in the point-to-point setting. The first contribution involves transform coding with decoder side information. In this setting, side information is only available to the decoder, whereas...
In lossy predictive coding of Differential Pulse Code Modulation (DPCM) type, quantization performed in the prediction loop induces propagation of quantization errors, resulting in biased predictions of the subsequent samples. In this work, we aim to alleviate the negative effect of quantization errors on the robustness of prediction. We propose some practical techniques for context modeling of quantization...
Embedded quantization is a mechanism employed by lossy image coding systems to successively refine the distortion of an image. Commonly, it is conducted through a uniform scalar dead zone quantizer (USDQ) together with a bitplane coding strategy (BPC). Although this scheme is convenient for current hardware architectures and achieves competitive coding performance, it establishes the embedded quantizer...
Randomized (dithered) quantization is a method capable of achieving white reconstruction error independent of the source. Dithered quantizers have traditionally been considered within their natural setting of uniform quantization. In this paper we extend conventional dithered quantization to nonuniform quantization, via a subterfage: dithering is performed in the companded domain. Closed form necessary...
This paper presents an MPEG-4 AAC decoder described in VHDL language and compliant with the Brazilian Digital Television standard (SBTVD). It has been synthesized to an Altera Cyclone II 2C35 FPGA using 26549 logic elements and 248704 memory bits. The implemented architecture has been verified using an Altera DE2 prototyping board, being capable of decoding stereo signals coded as MPEG-4 AAC Low Complexity...
A practical approach to designing distributed transform codes for high-dimensional correlated Gaussian vectors is presented. In this approach, source-splitting based on linear approximations is used to achieve arbitrary rate-pairs, by using only Wyner-Ziv (WZ) quantizers. The optimal bit-allocation among a dependent set of WZ quantizers is found by using a tree-search algorithm. Experimental results...
Distributed Video Coding (DVC) in transform domains could yield significant coding gains over the pixel domain. While employing different coding modes in DVC, it is still difficult to fully compress the source data without increasing the complexity at the encoder side. In this paper, we first propose a particular Run-Length-Coding (RLC) coding mode to efficiently compress the continuous zero symbols...
We consider a two-hop distributed relaying network using orthogonal space-time block codes (OSTBC), where several relays using Decode-Forward (DF) support the transmission from one source to one destination. In order to mitigate the impact of error propagation for DF, an inter-relay cooperation (IRC) scheme allowing message exchanges among the relays was presented in our previous work based on punctured...
The paper proposes a new approach for evaluating the security levels of digital watermarking schemes, which is more in line with the formulation proposed in cryptography. We first exhibit the class of equivalent decoding keys. These are the keys allowing a reliable decoding of contents watermarked with the secret key. Then, we evaluate the probability that the adversary picks an equivalent key. The...
In this paper, the combination of distributed Interleave-Division-Multiplexing-Space-Time Codes (IDM-STCs) with Orthogonal Frequency Division Multiplexing (OFDM) in two-hop relay systems applying Decode-and-Forward (DF) is investigated. In order to cope with erroneous decoding at the relays, a model to capture the decoding reliabilities of the relays is formulated and a method to incorporate these...
In this paper, we study the achievable rate region of two-user Gaussian broadcast channel (GBC) when the messages to be transmitted to both the users take values from finite signal sets and the received signal is quantized at both the users. We refer to this channel as quantized broadcast channel (QBC). We first observe that the capacity region defined for a GBC does not carry over as such to QBC...
This paper presents an approach to perform bit rate reduction Transco ding by video segmentation. The paper shows how a high performance distributed video transcoder can be built using multiple processing units and a Message Passing Interface based parallel programming model. The computation parallelization and data distribution among computing units is discussed. For data distribution coarse grain...
In quantized control system, the control system performance is degraded by different kinds of noise, but also the noise can make the encoder/decoder pairs overflow. In the latter case, we cannot get the effective information of the state. In this paper, the noise flag method which classifies the different kinds of noise is proposed to make the bound less conservative. The new method solves the problem...
As the High dynamic range (HDR) images generally have more than 10 bit/1024 colors per channel, its enormous data size often needs to be reduced when transmitting or storing the images. Thus development for functional compression is one of important research topics. Recently a lot of techniques for the HDR image compression are being suggested, and several two-layer coding algorithms which separately...
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